GGH1503
Learning Unit 1
ENVIRONMENTAL CHALLENGES, THEIR CAUSES AND SUSTAINABILITY
Contents
1.1
INTRODUCTION ........................................................................................................ 1
1.2
AIM AND LEARNING OUTCOMES ........................................................................... 3
1.3
PRESCRIBED MATERIAL......................................................................................... 4
1.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 5
1.4.1
What is the environment and what is environmental science?...................... 5
1.4.2
What are ecological footprints and why do we have environmental
challenges?...................................................................................................................... 6
Open Rubric
1.4.3
What is sustainability?...................................................................................... 7
1.4.4
What are environmental ethics?....................................................................... 8
1.4.5
What is environmental justice? ........................................................................ 9
1.5
CAPSTONE ACTIVITY ............................................................................................ 11
1.6
SELF-TEST .............................................................................................................. 11
1.7
CONCLUSION ......................................................................................................... 12
1.8
REFERENCES ......................................................................................................... 12
LEARNING UNIT 1
ENVIRONMENTAL CHALLENGES, THEIR CAUSES AND SUSTAINABILITY
Author: Leani de Vries
Co-authors: Chris Vlok and Peter Schmitz
Academic editor: Kristy Langerman
1
Overflowing waste (Source: Pixabay, RitaE)
"As the world's dominant animal, we have an awesome power to degrade or sustain
our life-support system."
(Miller & Spoolman, 2018:10)
1.1
INTRODUCTION
Humankind is facing an incredible challenge when it comes to a wide variety of humaninduced environmental degradation, including deforestation, pollution and climate
change, to name just a few. This is clear when consulting scientific research across
various academic disciplines and considering the state of our environment. Land
degradation and desertification, for example, are amongst the most critical
environmental challenges facing the country given the implications these have on food
security, urbanisation, poverty, climate change and biodiversity (Government of South
Africa, 2020).
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All images used in this learning unit are from free, publicly accessible sources.
https://pixabay.com/photos/garbage-waste-container-waste-2729608/ (RitaE)
https://pixabay.com/illustrations/ecological-footprint-4123696/ (Colin Behrens)
https://search.creativecommons.org/photos/1ba2bd87-27c0-47b9-9f2f-11d1ccdb61e4 (United Nations Photo)
https://search.creativecommons.org/photos/635d5a3e-c77c-4083-8a81-1fb60e06e25b (UNESCO Africa)
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According to Miller and Spoolman (2018), the human impact is large and growing,
which jeopardises Earth's species and biological life centres. We are living
unsustainably, which means that we are wasting, depleting and degrading the natural
capital we need to thrive, such as water, air and soil (Miller & Spoolman, 2018). The
image above of waste overflowing from a bin into a natural area is an example of
unsustainable living.
We are facing a complex, interconnected network of challenges, where each challenge
directly or indirectly causes a number of others. All environmental challenges are of
humankind's own making, but they were neither caused deliberately nor created
overnight. They developed over several centuries as a result of population growth, the
use of natural resources and the production of waste products. More specifically, the
origin of our current environmental challenges lies in humankind's ability to change the
environment and dominate Earth to survive and improve the standard of living, as well
as the human-centred (anthropocentric) worldview that many of us hold.
Understanding this complex network of challenges is tricky but necessary if we are to
comprehend the environmental issues of our time.
In 2015, 'The 2030 Agenda for Sustainable Development' was adopted by all United
Nations Member States, including South Africa and 53 other African countries.
Accompanying the Agenda are 17 Sustainable Development Goals (SDGs) that aim
to bring developed and developing countries together in a global partnership to
address pressing social, economic and environmental sustainability challenges. It is
generally acknowledged that environmental challenges constitute one of the major
concerns of the 21st century, but there is some disagreement about the seriousness
of the different challenges and whether we really are facing an environmental crisis.
This strongly relates to the different environmental worldviews that people hold, the
application of environmental ethics, science, the media, as well as our geographical
location (Eden & Geoghegan, 2017). For example, environmentalism from the global
North has historically focused primarily on the conservation of nature, while
environmentalism from the global South centres poverty as the cornerstone cause and
effect of environmental challenges (Lawhon, 2013).
In this learning unit, you are going to learn more about what the environment is and
the importance of environmental science in understanding and addressing our most
pressing environmental challenges. You will also learn more about humans' footprint
on the environment and how they are informed by different environmental ethics and
views. You will notice that the environmental concerns of the more developed nations
differ from those of the less developed nations, but since we all share the same planet,
we must work together to solve our environmental challenges as the actions of one
country affects another. Furthermore, the prescribed study material will provide you
with the most important terminology and concepts, in other words, the 'environmental
language' scientists use.
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ACTIVITY 1.1: A SOUTH AFRICAN
LENS ON THE SUSTAINABLE DEVELOPMENT GOALS
(SDGs)
Instructions
 Use the following link to explore South Africa's progress towards achieving
the 17 SDGs: https://south-africa.goaltracker.org/platform/south-africa.
 Select and investigate one goal (SDG) of your choice using the following link:
https://south-africa.goaltracker.org/platform/south-africa/goals.
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 1.1: A South African lens on the
Sustainable Development Goals (SDGs)" by following the task outlined
below.
Purpose
To encourage you to explore the 17 SDGs, the targets that are set within each goal,
as well as South Africa's progress towards achieving these goals. This will help to
expand your knowledge of sustainability and sustainable development.
Task
In your blog post, share with fellow students:
1. a short summary, in your own words, of the goal and main targets set within
the goal you selected to investigate, and
2. your thoughts on how South Africa is progressing towards achieving this goal.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
1.2 AIM AND LEARNING OUTCOMES
This learning unit aims to introduce you to the central themes of the module that are
grounded in the principles of environmental science. Once you have completed this
learning unit, you can use the outcomes to assess the quality of your learning
experience. Assess whether you meet each aim and outcome with confidence. If not,
you are advised to dedicate more time to those you are still having trouble with or do
not understand properly.
At the end of this learning unit, you should be able to do the following:





Describe what the environment is and what environmental science is.
Explain how our ecological footprints are affecting the Earth.
Explain why we have environmental challenges.
Describe sustainability and sustainable development.
Explain and distinguish between the major types of environmental ethics and
views on sustainability and conservation.
 Describe environmental equity and environmental justice.
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1.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from three
prescribed open-access books.
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.

o
o
o
o
Chapter 1: Environmental Science
1.1: The Earth, Humans, & the Environment
1.3: Environment & Sustainability
1.4: Environmental Ethics
1.5: Environmental Justice & Indigenous Struggles
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.

o
o
o
o
o
o
Chapter 1: Introduction to Environmental Science
1.4: Environment and Environmental Science
1.6: Sustainability and Sustainable Development
1.7: The IPAT Equation
1.8: The Precautionary Principle
1.9: What is the Environment Worth to You?
1.10: Global Perspective
Theis, T. & Tomkin, J. (Editors). 2018. Sustainability: A Comprehensive
Foundation. OpenStax CNX. Available at:
https://legacy.cnx.org/content/col11325/latest/pdf.

o
o
o
Chapter 1: An Introduction to Sustainability: Humanity and the
Environment
1.2: What is Sustainability?
1.3: The IPAT Equation
1.5: Challenges for Sustainability
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This table summarises the study material for this learning unit.
Prescribed material
Zehnder et al.,
2018
Chapter 1
Fisher,
2018
Chapter 1
Relevant sections
1.4
1.1, 1.3, 1.4 and 1.5
1.4, 1.6, 1.7, 1.8, 1.9
and 1.10
Theis & Tomkin,
2018
Chapter 1
1.2, 1.3 and 1.5
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 1.2 and will help you to find your way through the study material.
1.4.1 What is the environment and what is environmental science?
Study chapter 1.1 in Fisher (2018) and chapter 1.4 in Zehnder et al. (2018).
Summary
 The environment refers to all living and non-living things on Earth, including
related physical, chemical and biological factors and processes.
 The first forms of life on Earth are believed to be microorganisms that existed
billions of years ago after which plants and animals appeared around 130 to
200 million years ago. Human species have been inhabiting the Earth for the
last 2,5 million years.
 Environmental science is the interdisciplinary study of the environment,
including the interaction of the living and non-living parts of the environment,
and the impact that humans have on the environment.
 To ensure that Earth's resources are used in an equitable, ethical and
sustainable manner, environmental science offers an understanding of (1) how
humans impact the environment and (2) the scientific principles that govern
living and non-living things.
 The global rate and scale of environmental change are unprecedented.
 Environmental engineering is a field of engineering that involves solving
environmental problems and designing systems that use the knowledge and
concepts from environmental science and ecology.
 Environmentalism is a social movement dedicated to protecting the
environment and natural resources through citizen activism.
 Ecosystem services refer to (1) provisioning services such as food and water;
(2) regulating services such as flood control, drought, and disease; (3)
supporting services such as soil formation and nutrient cycling; and (4) cultural
services such as recreational, spiritual, religious and other nonmaterial
benefits.
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1.4.2 What are ecological footprints and why do we have environmental
challenges?
Study chapters 1.3 and 1.4 in Fisher (2018), chapters 1.7, 1.8 and 1.10 in
Zehnder et al. (2018) and chapter 1.3 in Theis and Tomkin (2018).
Summary
 The three primary reasons for the unprecedented rate and scale of
environmental change, include (1) mechanisation of industry and agriculture
that has involved increased productivity, technological innovation, use of fossil
fuels and resource consumption and waste; (2) global resource consumption
and purchasing power inequities as a result of unprecedented, exponential
population growth; and (3) the nature of environmental change and impact that
involves the introduction of unnatural chemicals and materials into the
environment.
 An ecological footprint (EF) refers to the impact we have on the environment. It
was first developed by ecologist and planner William Rees. An EF is essentially
an 'accounting tool' that measures the biologically productive land required by
humans for our production, consumption and waste needs. In other words, how
much of the environmental functions of the Earth is needed to support humans.
 The per capita ecological footprint applies the above definition, but per
individual requirement (per person).
 The IPAT equation is one way of measuring the impact of populations; for
example, urban populations.
I = P x A x T where:
I represent the impact on an environment
P is the size of the relevant human population
A is the affluence of the population/the level of consumption per person
T is the technology available to the population/the impact per unit of
consumption
 The precautionary principle is considered an important concept in
environmental sustainability and refers to the action of taking caution given
incomplete knowledge of the potential harm of something. The precautionary
principle is also considered as an aspect of environmental risk management.
 There are several indicators of global environmental stress, including (1)
deforestation; (2) soil degradation; (3) lack of access to fresh water; (4)
overfishing; (5) threatened biodiversity; (6) rising greenhouse gas emissions;
(7) high levels of toxicity and presence of toxic chemicals in the environment;
(8) hazardous waste pollution and (9) increased waste generation.
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
To solve environmental challenges, we require a global perspective, especially
given the growth of the human population and the scale of our global impact.
ACTIVITY 1.2: CALCULATING MY
ECOLOGICAL FOOTPRINT
Instructions
 Use the following link and do the quiz to calculate your ecological footprint:
https://www.footprintcalculator.org/.
 Explore the results once you have completed the quiz and your footprint has
been calculated.
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 1.2: Calculating my ecological
footprint" by following the task outlined below.
Purpose
To provide you with a platform to reflect on how your everyday life is impacting the
environment. This will help to expand your knowledge on per capita ecological
footprints and further your understanding of living sustainably.
Task
In your blog post, share with fellow students:
1. how well you think you performed in terms of your ecological footprint, and
2. the aspects of your everyday life you could potentially change to live more
sustainably.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
1.4.3 What is sustainability?
Study chapter 1.3 in Fisher (2018), chapter 1.6 in Zehnder et al. (2018) and
chapters 1.2 and 1.5 in Theis and Tomkin (2018).
Summary
 Sustainability connects the triple bottomline, including (1) social equity; (2) economic
productivity; and (3) environmental quality. It
requires that we limit our environmental
impact while promoting economic well-being
and social equity.
 The concept of sustainable development was popularised in 1987 in the report
'Our Common Future', more generally known as the 'Brundtland Report' of the
World Commission on Environment and Development (WCED). Sustainability
and sustainable development are used interchangeably. Sustainable
development refers to the development that meets the needs of the present
without compromising the ability of future generations to meet their own needs.
It is an ongoing process in which development satisfies present and future
needs.
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

The ideology of sustainability traces back to indigenous cultures. Today,
sustainability includes socio-political, scientific and cultural challenges as it
pertains to living within the means of the Earth and not impairing its function, or
the ability of future generations to do the same.
Within the sustainability paradigm, trade-offs of its three main elements are also
considered, despite it usually being considered of equal importance; for
example, (1) strong sustainability is the notion where trade-offs among natural,
human and social capital are not allowed/restricted; or (2) weak sustainability
is the notion where trade-offs are unrestricted or have few limits. Whether a
strong or weak sustainability paradigm is followed, a functioning environment
underpins both society and the economy.
1.4.4 What are environmental ethics?
Study chapter 1.4 in Fisher (2018) and chapter 1.9 in Zehnder et al. (2018).
Summary
 Ethical attitudes and behaviours determine the way we interact with the
environment and natural resources.
 There are various types of environmental ethics humans can associate with,
including:
(1) A frontier ethic – assumes that the Earth has an unlimited supply of
resources; if resources run out in an area it is assumed that this could either
be replaced from elsewhere or substituted by human ingenuity; views
humans as the masters of the planet; is anthropocentric (human centred),
and considers the needs of humans only;
(2) A sustainable ethic – treats the Earth with the belief that its resources are
limited; assumes that humans must use and conserve resources to allow
continued future use and protect the integrity of the environment; assumes
that humans are part of the natural environment and share Earth's
resources with other living things; and believes that humans are impacted
by the health of the environment and natural laws; may be either
anthropocentric or biocentric (life-centred); and
(3) A land ethic – coined by Aldo Leopold, it considers humans not as the
conqueror of the land community but as respecting members and citizens
of it.
 Environmental conservation can also be viewed and justified from multiple
perspectives, including:
(1) A utilitarian justification – we should protect the environment because doing
so will provide direct economic benefit to people;
(2) An ecological justification – we should protect the environment because
doing so will protect species and acknowledges the many ecosystem
services we derive from healthy ecosystems;
(3) An aesthetic justification – acknowledges that many people enjoy the
outdoors and do not want to live in a world without wilderness; and
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
(4) A moral justification – represents the belief that various aspects of the
environment have a right to exist and it is our moral obligation to allow them
to persist.
Environmental equity is related to the equitable and sustainable distribution of
resources. Currently, just one-fifth of the global population is consuming threequarters of the Earth's resources.
ACTIVITY 1.3: MY VIEW ON ENVIRONMENTAL
CONSERVATION
Instructions
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 1.3: My view on environmental
conservation" by following the task outlined below.
Purpose
To create a platform where you can reflect on your understanding of, and justification
for, environmental conservation. This will assist you in coming to terms with the
variety of environmental viewpoints and ethics that humans associate themselves
with.
Task
In your blog post, share with fellow students:
1. your understanding of environmental conservation, and
2. which of the four perspectives you relate to most when it comes to justifying
the need for environmental conservation.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
1.4.5 What is environmental justice?
Study chapter 1.5 in Fisher (2018).
Summary
 Environmental justice is defined as the fair treatment and meaningful
involvement of all people regardless of race, nationality or income in terms of
the development, implementation and enforcement of environmental laws,
policies and regulations.
 Environment justice involves (1) equal protection from environmental and
health hazards, and (2) equal access to the decision-making process towards
a healthy environment. Environmental racism, for example, is one opposite of
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this. Environmental justice involves the incorporation of indigenous peoples
(indigenous to particular regions and areas) and indigenous knowledge to
integrate their spiritual, cultural, economic, social, political, territorial and
philosophical ideals and rights.
INDIGENOUS KNOWLEDGE SYSTEMS AND ITS KEY ROLE
IN UNDERSTANDING OUR LIVING EARTH
What is indigenization and decolonization and what does it mean for
the knowledge we acquire?
“Indigenization is a process of naturalizing Indigenous knowledge
systems and making them evident to transform spaces, places, and
hearts. In the context of post-secondary education, this involves
bringing Indigenous knowledge and approaches together with
Western knowledge systems. This benefits not only Indigenous
students but all students, teachers, and community members
involved or impacted by Indigenization. Indigenous knowledge
systems are embedded in relationship to specific lands, culture, and
community.” (Antoine et al., 2018)
“Decolonization refers to the process of deconstructing colonial
ideologies of the superiority and privilege of Western thought and
approaches.” (Antoine et al., 2018)
According to Antoine et al. (2018), the accurate incorporation of
Indigenous knowledge systems must be informed by a proper
understanding of Indigenous epistemologies (how knowledge can be
known) and pedagogies (how knowledge can be taught).
Some notable commonalities of Indigenous societies and knowledge
systems worldwide are listed below (Antoine et al., 2018):
Indigenous epistemologies
 Relationality (we are all related to each other, to the natural
environment, and to the spiritual world)
 Sacred and secular (worldviews that are inclusive of both the
sacred and the secular)
 Holism (focus on the whole picture)
Indigenous pedagogies
 Personal and holistic (focus on the development of a human being
as a whole person)
 Experiential (learning by doing)
 Place-based learning (connect learning to a specific place)
 Intergenerational (passing on of wisdom and knowledge to youth)
For the purpose of GGH1503, we will have a look at some examples of
Indigenous knowledge systems, throughout some of the learning units,
and what role it plays in the production and transfer of knowledge that
relate to real-life geographic and environmental science topics.
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1.5 CAPSTONE ACTIVITY
LEARNING UNIT 1: CAPSTONE ACTIVITY
Instructions
 Go to the Discussions tool on the GGH1503 module site.
 Go to the topic entitled Learning Unit 1: Capstone Activity.
 Reply by providing your response on the tasks detailed below.
Purpose
To provide you with the opportunity to showcase your holistic understanding of the
environmental challenges facing Africa. It equips you to meet the first of the module's
three main learning outcomes (as listed in the module overview) by providing you
with the opportunity to explore the complex interrelationships between humans and
the environment.
Task instructions
For this activity you will need to consult the following material:
UNEP. 2016. GEO-6 Regional Assessment for Africa. United Nations
Environment Programme, Nairobi, Kenya. You can download the PDF from
http://wedocs.unep.org/bitstream/handle/20.500.11822/7595/GEO_Africa_2
01611.pdf?sequence=1&isAllowed=y or read the e-book at
http://content.yudu.com/web/2y3n2/0A2y3n3/GEO6Africa/html/index.html?origin=reader.
You do not need to read the entire report. Browse to and read only Chapter 1:
Regional Context and Priorities (pages 12 to 23) to gain an overview of Africa's
environmental challenges and respond to the tasks below.
Task
1. List the environmental priority issues identified in the report for the African
region at present.
2. Provide a summary of each of the four emerging issues set to affect Africa's
ecological future.
1.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
1.6.1 What is the difference between environmental science, environmental
engineering and environmentalism?
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1.6.2 Which one of the following suggests that when the effects of human activity
are poorly understood, we must presume that some level of harm may exist to
the environment, and thus must proceed with that activity carefully?
A. Sustainability ethic
B. Precautionary principle
C. Environmental harm dictum
D. Environmental injustice
E. Presumptive principle
1.6.3 What is the triple bottom-line?
1.6.4 Identify an environmental problem that requires a global perspective for a
solution. How might this problem be examined from a variety of environmental
conservation perspectives?
1.6.5 If I assume that the Earth has an unlimited supply of resources and that
humans are the masters of the planet, I associate with a/an … environmental
ethic.
1.7 CONCLUSION
Upon completion of this learning unit, you should realise that we face an array of
serious environmental challenges. You should have identified that sustainability holds
the key to our survival on Earth. Sustainability involves a lot of environmental concepts
and terminology (for example, triple bottom-line), with which you should now be
familiar. Using this knowledge, consider what sustainability means to you. Is it
important for you to lead a sustainable lifestyle and do you think it would make a
difference in achieving global sustainability? Now that you have reached the end of
learning unit 1, you may proceed to learning unit 2.
1.8 REFERENCES
Antoine, A., Mason, R., Mason, R., Palahicky, S. & de France, C.R. 2018. Pulling
Together: A Guide for Curriculum Developers. BCcampus. Available at:
https://opentextbc.ca/indigenizationcurriculumdevelopers/.
Eden, S. & Geoghegan, H. 2017. Environmental issues and public understanding.
The International Encyclopedia of Geography. 1-9. DOI:
10.1002/9781118786352.wbieg1065.
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
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Government of South Africa. 2020. Environment. Available at:
https://www.gov.za/about-sa/environment.
Lawhon, M. 2013. Situated, Networked Environmentalisms: A Case for
Environmental Theory from the South. Geography Compass. 7(2):128-138.
Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Theis, T & Tomkin, J. (Editors). 2018. Sustainability: A Comprehensive Foundation.
OpenStax CNX. Available at: https://legacy.cnx.org/content/col11325/latest/pdf.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
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GGH1503
Learning Unit 2
SCIENCE, MATTER, ENERGY AND SYSTEMS
Contents
2.1
INTRODUCTION ........................................................................................................ 1
2.2
AIM AND LEARNING OUTCOMES ........................................................................... 3
2.3
PRESCRIBED MATERIAL......................................................................................... 3
2.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 4
2.4.1
What is science? ............................................................................................... 4
2.4.2
What is matter? ................................................................................................. 6
2.4.3
What is energy, what are systems and how can these be changed? ............ 7
2.5
CAPSTONE ACTIVITY ............................................................................................ 10
2.6
SELF-TEST .............................................................................................................. 11
2.7
CONCLUSION ......................................................................................................... 12
2.8
REFERENCES ......................................................................................................... 13
LEARNING UNIT 2
SCIENCE, MATTER, ENERGY AND SYSTEMS
Authors: Leani de Vries and Peter Schmitz
Co-author: Chris Vlok
Academic editor: Kristy Langerman
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Laboratory plants (Source: Unsplash.com, Chuttersnap)
"Science generates solutions for everyday life and helps us to answer the great
mysteries of the universe. In other words, science is one of the most important
channels of knowledge. It has a specific role, as well as a variety of functions for the
benefit of our society: creating new knowledge, improving education, and increasing
the quality of our lives."
"To face sustainable development challenges, governments and citizens alike must
understand the language of science and must become scientifically literate."
(UNESCO, 2019)
2.1 INTRODUCTION
The image above depicts plants placed in beakers in a laboratory used for
experimentation and observation. Can you think how this image of plants is also a
depiction of matter, energy and systems?
To understand the environmental challenges we face today, it is essential to learn
more about matter, energy and the natural systems or laws that govern life on Earth.
Every living thing, the food you eat, the ground you walk on, the water you drink, even
the air you breathe, consists of matter. Every step any living being takes, every
kilometre you drive, the heat you use to cook your meal, the growth of every plant,
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All images used in this learning unit are from free, publicly accessible sources.
https://unsplash.com/photos/UmncJq4KPcA (Chuttersnap)
https://www.pexels.com/photo/faceless-laboratory-technician-conducting-chemical-test-3825368/ (RF._.studio)
https://www.pexels.com/photo/crop-chemist-holding-in-hands-molecule-model-3825527/ (RF._.studio)
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even the light you study by is a form of energy or requires energy. To put it simply, we
can say that our living Earth consists of matter and is sustained by energy. UNESCO
(2019) describes science as "the greatest collective endeavour". We can consider
science a critical field of study as it aims to discover how nature works and what
happens in nature (Miller & Spoolman, 2018).
In this learning unit, you will learn that our living world is a vast collection of complex
systems that consist of matter and require energy to function. You will learn what
matter is, what energy is, and that both matter and energy can be changed but never
created or destroyed. The fact that matter and energy can neither be created nor
destroyed is of immense importance in environmental systems and processes. It might
well be the single most important scientific truth for any environmental scientist or
environmental manager to know.
But what is science? For that matter, what is scientific? In this learning unit, you are
going to learn the answers to these questions. You are going to know how scientists
think and how they 'do science'. You will realise that while science is open to change,
and creative and flexible in constant pursuit of improving knowledge, not all science
are reliable science. (Miller & Spoolman, 2018). You must know these things to
understand that the scientific concerns about the environment are not born from
emotion, sentiment, nostalgia or non-scientific thinking but based on what we think to
be the provable, verifiable, reality.
Lastly, we will introduce you to one of the most valuable tools offered by the field of
geographic science. Maps are crucial geographic tools that have evolved over the
centuries and enable researchers, policymakers, and just about anyone to visually
represent human-environment relationships. This is significant for understanding and
addressing our time's environmental challenges and pursuing sustainable
development goals (Ingram, 2020; Kraak et al., 2020).
ACTIVITY 2.1: SCIENCE IN THE MEDIA
Instructions
 Find a newspaper or magazine article (in print or on the internet) that
describes a scientific finding, scientific research or scientific argument.
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 2.1: Science in the Media" by following
the task outlined below.
Purpose
To expose you to the broad fields of scientific research and how scientific findings
and arguments are presented in the media. This will help you to grasp the value of
science in understanding our living Earth.
Task
In your blog post, share with fellow students:
2
1. a short summary of what the scientific newspaper or magazine article you
have found is about and what is or has been researched, discovered or
argued,
2. your assessment of the quality of journalism in conveying the scientific
finding, and
3. how the scientific article might help solve a real-life issue or contribute to what
is known about the specific scientific field at hand.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on other students' posts.
2.2 AIM AND LEARNING OUTCOMES
This learning unit aims to introduce you to the importance of science and understand
the roles that matter, energy and systems play in sustaining our living Earth. The
learning unit also aims to introduce you to maps and their importance in science and
sustainability. Once you have completed this learning unit, you can use the outcomes
to assess your learning experience. Assess whether you meet each aim and outcome
with confidence. If not, you are advised to dedicate more time to those you are still
having trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:






Analyse the nature of science and the role of science in our daily lives.
Explain what matter is and discuss its characteristics.
Describe what energy is and explain how it can be changed.
Discuss what systems are.
Understand the importance of geographic tools.
Define maps and identify basic map elements.
2.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from two prescribed
open-access books.
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.

o
Chapter 1: Environmental Science
1.2: The Process of Science
3

o
o
Chapter 2: Matter, Energy, & Life
2.1: Matter
2.2: Energy
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.

o
o
o
Chapter 1: Introduction to Environmental Science
1.1: The Chemical and Biological Foundations of Life
1.2: Biological Molecules
1.5: The Process of Science
This table summarises the study material for this learning unit.
Relevant sections
2.4
Prescribed material
Fisher,
Zehnder et al.,
2018
2018
Chapters 1 & 2
Chapter 1
1.2, 2.1 and 2.2
1.1, 1.2 and 1.5
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 2.2 and will help you to find your way through the study material.
2.4.1 What is science?
Study chapter 1.2 in Fisher (2018) and chapter 1.5 in Zehnder et al. (2018).
Summary
 Science (from the Latin scientia, meaning
'knowledge') is defined as the process of
gaining knowledge about the natural world.
Science investigates the realm of material
phenomena that can be observed and
measured (i.e. matter and energy).
 The fields of science are diverse and include astronomy, computer sciences,
psychology, mathematics, to name only a few. Those fields of science related
to the physical world are considered natural sciences include physics, geology,
biology and chemistry. Environmental science is a cross-disciplinary natural
science.
4
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
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


Science has and will continue to transform human existence; for example,
through the technological revolutions that science is responsible for.
There are two types of science, namely basic science and applied science.
Basic science is the 'pure' science that seeks to expand knowledge, while
applied science aims to solve real-world problems.
What distinguishes sciences from non-sciences is the openness to disproving
an idea. In other words, scientific understandings are always flexible to
modification by further information.
The scientific method is a method of research with defined steps. The methods
of science include careful observation, record-keeping, logical and
mathematical reasoning, experimentation, and submitting conclusions to
others' scrutiny. Scientific hypotheses, theories and laws form important
aspects.
Scientific experiments have one or more variables and one or more controls.
An experimental variable (independent variable) is any part of the experiment
that can vary or change as it is manipulated throughout the experiment. A
controlled variable (dependent variable) is any part of the experiment that
changes as a function of the independent variable (the variable by which we
measure change in response to the independent variable). A control group is
the group of test subjects that is not changing and does not receive the
experimental treatment, while the group that does, is known as the
experimental group.
Science requires considerable imagination and creativity and has significant
practical implications. All fields of science have the ultimate goal to acquire
knowledge. This makes curiosity and scientific inquiry the driving forces for
science development.
Two methods of logic are inductive and deductive reasoning. Inductive
reasoning uses observations to make conclusions, while deductive reasoning
is hypothesis-based and uses this to predict results. Resultantly, there are two
main pathways of scientific study namely descriptive/discovery science and
hypothesis-based science. The former aims to observe, explore and discover,
while the latter uses a specific question or problem whereby a potential answer
or solution can be tested.
An important aspect of scientific research is peer-review since scientific work
must be transparent and open to critique. Scientists must share their findings
with others to develop their discoveries. This is done at scientific meetings,
conferences, and most commonly, by publishing peer-reviewed articles in
scientific journals.
5
HOW PEER REVIEW WORKS
Instructions
 Watch the following video:
https://www.youtube.com/watch?v=rOCQZ7QnoN0 (3:16 minutes)
Purpose
 The video "Peer Review in Three Minutes" is a useful summary of the peer
review process for scholarly research. This will help you to understand the
most common platform through which reliable scientific findings are shared.
2.4.2 What is matter?
Study chapter 2.1 in Fisher (2018) and chapters 1.1 and 1.2 in Zehnder et al.
(2018).
Summary
 Matter is anything that occupies space and has mass.
 All matter on Earth is composed of elements (substances
with specific chemical and physical properties). Elements
are designated by their chemical symbols, possess unique
properties and are made of atoms (the smallest unit of
matter that retains all chemical properties of an element,
each with a set number of protons and unique properties).
 Of the 118 elements found in the universe, only 92 occur naturally, of which the
rest are synthesised in laboratories and are unstable. The five elements
common to all living organisms are oxygen (O), carbon (C), hydrogen (H),
nitrogen (N), and phosphorous (P).
 At the most basic level, all organisms are made of a combination of elements.
Two or more atoms join together through chemical bonds to form molecules.
 Each atom has a nucleus (the centre of the atom) that contains protons
(positively charged particles) and neutrons (uncharged particles). Electrons
(negatively charged particles) orbit the nucleus of an atom.
 Each element contains a different number of protons and neutrons, giving it its
atomic number (equal to the number of protons) and mass number (number of
protons plus the number of neutrons).
 Isotopes are various forms of the same element with the same number of
protons but a different number of neutrons. Radioactive isotopes or
radioisotopes are unstable isotopes that lose protons, other subatomic
particles, or energy to form more stable elements such as Carbon-14 (14C).
Radioactive decay describes the energy loss that occurs when an unstable
atom's nucleus releases radiation (and mass).
 An ion is an electrically charged atom or combination of atoms (the number of
electrons does not equal the number of protons). Positive ions are called
cations and negative ions are called anions.
6
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Ionic bonds (between an anion and a cation) and covalent bonds (when
electrons are shared between two atoms) are strong bonds formed between
two atoms. Covalent bonds are the strongest and most commons form of
chemical bonds in organisms and, unlike most ionic bonds, do not dissociate in
water.
Water is critical to life as we know it (it is polar, stabilises temperature, is an
excellent solvent and is cohesive).
pH refers to the measure of acidity or alkalinity of a solution (the concentration
of hydrogen ions or H+) and ranges from a scale of 0-14. Pure water is neutral
(pH of 7.0). Anything below 7.0 is acidic, and anything above 7.0 is alkaline.
Acids provide hydrogen ions (H+) and lower pH, while bases provide hydroxide
ions (OH-) and raise pH. Buffers readily absorb excess H+ or OH-.
Besides water, the molecules necessary for life are organic (carbon-based).
Hydrocarbons are organic molecules that contain carbon covalently bonded to
hydrogen. The four major classes of organic molecules called biological
molecules/biomolecules are (1) carbohydrates, (2) lipids, (3) proteins and (4)
nucleic acids.
The basic functional unit of life is a cell, and all organisms are made up of one
or more cells.
2.4.3 What is energy, what are systems and how can these be changed?
Study chapter 2.2 in Fisher (2018).
Summary
 Energy is the capacity to do work, transfer heat or create some kind of change.
Virtually, every task performed by living organisms requires energy.
 Different types of energy include electrical energy, light energy, mechanical
energy and heat energy.
 Energy associated with objects in motion is called kinetic energy, while potential
energy is the energy by an object's position and the force of gravity acting on
it. Chemical energy is the potential energy within chemical bonds that is
released when bonds are broken.
 Bioenergetics describe the concept of energy flow through living systems, such
as cells. All chemical reactions that take place inside cells are referred to as a
cell's metabolism.
 Thermodynamics refers to the study of energy and energy transfer involving
physical matter.
 Energy is subject to physical laws. The laws of thermodynamics govern the
transfer of energy in and among all systems in the universe.
 According to the first law of thermodynamics, the universe's total amount of
energy is constant and conserved. Energy may be transferred from place to
place or transformed into different forms, but it cannot be created or destroyed.
7
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

According to the second law of thermodynamics, energy transfers and
transformations are never completely efficient. In every energy transfer, some
amount of energy is lost in an unusable form.
A system is any set of interacting components that function in some regular
way. In an open system, energy can be exchanged with its surroundings. In a
closed system, there is no exchange of energy with the surroundings.
The concepts of order and disorder are important in physical systems. The
more energy that is lost by a system to its surroundings, the less ordered and
more random the system is. The measure of randomness or disorder within a
system is called entropy. High entropy means high disorder and low usable
energy.
ACTIVITY 2.2: HOW THE LAWS OF THERMODYNAMICS
APPLY TO MY EVERYDAY LIFE
Instructions
 Take a quick walk through your home, place of study or place of work.
 While you walk, try to identify at least five examples of everyday features that
exhibit either the first or the second law of thermodynamics.
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 2.2: How the laws of thermodynamics
apply to my everyday life" by following the task outlined below.
Purpose
To show you real-life examples of how scientific laws apply to your everyday life at
home, work or university, and to help expand your knowledge of energy.
Task
In your blog post, share with fellow students:
1. the list of five or more examples in which the first and/or second law of
thermodynamics are exhibited in your everyday life, and
2. a description of how the first and/or second law of thermodynamics applies
in each of these examples.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on other students' posts.
INTRODUCING GEOGRAPHIC TOOLS AND MAPS
The importance of geographic tools
 Geographic tools such as maps are essential to represent phenomena of our
living Earth visually. Well-designed maps, for example, display important
spatio-temporal patterns such as global population growth and climate
change.
 They help us improve our understanding of the relationship between humans
and their environment (both natural and artificial) and enable us to monitor
and plan sustainable development. Think back to the SDGs mentioned in the
module overview and in learning unit 1. Can you think of the importance of
geographic tools in achieving each of the 17 SDGs?
8
What are maps?
 A map is a graphic representation of the cultural and physical environment.
 Maps are reduced, selective and symbolised graphical representations of the
environment. In other words, they (1) are reproduced at a smaller scale than
the actual phenomenon being mapped, (2) include only items related to the
purpose of the map, and (3) contain items that are mapped by a
representative symbol.
 Cartography is the art or science of making maps. This means that you will
become a cartographer of sorts as you learn how to produce maps
throughout this module.
Basic map elements
Well-designed maps are a "functional visual communication device" that is visually
pleasing and accurate (Ingram, 2020). Maps consist of several parts called map
elements. These include a neat line, map body, graticule, insets, title, legend, label,
ancillary text, ancillary object, scale bar, directional indicator and metadata.
However, not all maps need to contain all these elements.
Essential map elements:
o Title: Focuses attention on the map's purpose and is typically centred at the top
of the map.
o Map body: The main visual focus of the map that shows the data. It is the only
map element that is required to produce a map.
o Map scale: Displays a suitable unit of measure for the map audience and
purpose and is used to measure linear relationships and distances on a map.
o Legend: Used to identify the features and symbols of a map.
o Directional indicator: This element is used to indicate a direction on a map
and is typically a North arrow.
o Label: Communicates attribute or ancillary information to the map user.
o Metadata/credits: Cites the source of data sets used to create a map.
o Graticule: A visual representation of a coordinate system or location scheme
used on a map.
9
Map Elements (Source: Ingram, 2020)
2.5 CAPSTONE ACTIVITY
LEARNING UNIT 2: CAPSTONE ACTIVITY
Instructions
 Go to the Discussions tool on the GGH1503 module site.
 Go to the topic entitled Learning Unit 2: Capstone Activity.
 Reply by providing your response on the tasks detailed below.
Purpose
To enable you to explore and display your holistic understanding of how our living
Earth consists of matter, is sustained by energy and is governed by natural systems
or laws. It also equips you to further your competence in meeting the first of the
10
module's three main learning outcomes (as listed in the module overview) by
providing you with the opportunity to explore the basic scientific fundamentals
involved in the natural environment.
Task instructions
For this activity, you will need to envision a fishpond in a friend's garden. Suppose
you are visiting your friend and observe that all the fish in the pond have
disappeared. Your friend, aware of your environmental expertise, asks for your help
in uncovering what might have caused the fish to disappear.
Task
1. Draw a map showing the made-up fishpond and immediate surroundings, like
rocks, lawn, pathways and trees on a piece of paper (in other words a
simplified map), including the basic map elements.
2. Use various colours, excluding black, such as blue to indicate water to draw
all the elements of the fishpond and surrounds that represent matter, and the
colour black to draw arrows that represent the flow of energy in the fishpond
system (tip: the flow of solar energy into the fishpond).
3. Use your map and your knowledge of the various steps in the scientific
method to come up with one or more explanations as to what might have
caused the fish to disappear.
4. Share your scanned map and explanations with other students in the
discussion topic.
2.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
2.6.1 Why does science require imagination and creativity?
2.6.2 Illustrate the scientific method using a flow-chart.
2.6.3 Which option is not one of the four major classes of organic compounds?
A. Nucleic acids
B. Water
C. Proteins
D. Carbohydrates
E. Lipids
11
2.6.4 Which term describes the complete set of chemical reactions that occur within
cells?
A. Metabolism
B. Cellular respiration
C. Calvin Cycle
D. Bioenergetics
E. Thermodynamics
2.6.5 How do the first and second laws of thermodynamics apply to our use of nonrenewable energy?
INDIGENOUS KNOWLEDGE SYSTEMS AND ITS KEY ROLE
IN UNDERSTANDING OUR LIVING EARTH
How does Indigenous knowledge enrich conventional science and
practices?
Watch the following videos:

https://www.youtube.com/watch?v=j3OepeDQJwY (6:38 minutes)

https://stemforall2019.videohall.com/presentations/1602 (3:00
minutes)

https://www.youtube.com/watch?v=1QRpnHoGivk (3:19 minutes)
2.7 CONCLUSION
You should now be able to understand what we mean when we say: We breathe O2,
we drink H2O, and we eat C6H12O6, while C14H9Cl5 will kill us. Even when organisms
die, the matter they consist of and the energy which kept them alive, have not and
cannot be destroyed. Your scientific vocabulary and basic scientific knowledge should
now have increased to such an extent that you will be able to understand the
complexity of life and our living world. Reflect on what this learning unit has meant for
the way you think about your own daily life. Consider how your lifestyle is sustained
by energy, matter and systems. Also, do you think applying the scientific method could
play a role in the way you approach problem-solving or the way you make sense of
observations from phenomena in our natural environment? Now that you have
reached the end of learning unit 2, you may proceed to learning unit 3.
12
2.8 REFERENCES
Fisher, M.R., (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Ingram, U. 2020. Introduction to Cartography. University System of Georgia.
Available at: https://alg.manifoldapp.org/projects/intro-cartography-ksu.
Kraak, M.J., Roth, R.E., Ricker, B., Kagawa, A. & Le Sourd, G. 2020. Mapping for a
Sustainable World. The United Nations. New York, NY (USA). Available at:
https://www.un.org/geospatial/sites/www.un.org.geospatial/files/MappingforaSustain
ableWorld20210124.pdf.
Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
UNESCO, 2019. Science for Society. https://en.unesco.org/themes/sciencesociety#:~:text=In%20other%20words%2C%20science%20is,societal%20needs%20
and%20global%20challenges.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
13
GGH1503
Learning Unit 3
ECOSYSTEMS: WHAT ARE THEY AND HOW DO THEY WORK?
Contents
3.1
INTRODUCTION ........................................................................................................ 1
3.2
AIM AND LEARNING OUTCOMES ........................................................................... 3
3.3
PRESCRIBED MATERIAL......................................................................................... 3
3.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 5
3.4.1
The biological organisation of life on Earth .................................................... 5
3.4.2
What is photosynthesis and how does energy enter ecosystems through
this process? ................................................................................................................... 5
3.4.3
What are ecosystems and how does energy flow through them? ................. 6
3.4.4
What happens to matter in an ecosystem? ..................................................... 9
3.4.5
What is soil and what part does it play in ecosystems?............................... 14
3.5
CAPSTONE ACTIVITY ............................................................................................ 15
3.6
SELF-TEST .............................................................................................................. 16
3.7
CONCLUSION ......................................................................................................... 17
3.8
REFERENCES ......................................................................................................... 17
LEARNING UNIT 3
ECOSYSTEMS: WHAT ARE THEY AND HOW DO THEY WORK?
Authors: Leani de Vries and Peter Schmitz
Academic editor: Kristy Langerman
1
Penguins at Boulder's Beach, Simon's Town, South Africa (Source: Unsplash.com, Casey
Allen)
"Ecologists call for greatly increased research on the condition of the world's
ecosystems to see how they are changing. This will help them develop strategies for
preventing or slowing their degradation."
(Miller & Spoolman, 2018:70)
3.1 INTRODUCTION
So far in this module, you have learned quite a lot about science, matter and energy,
and how humankind impacts the environment. However, you have learned relatively
little about the living environment, the organisms that live in it, the relationships among
them and their interactions with the non-living environment. That is what we are going
to focus on in this learning unit.
Life on Earth is extremely diverse and highly organised. An enormous variety of living
organisms live in – and depend on – biological communities, which are organised into
larger units, namely ecosystems. This interconnected complexity of living matter is
1
All images used in this learning unit are from free, publicly accessible sources.
https://unsplash.com/photos/UjpEGHu8uNU (Casey Allen)
https://pixabay.com/photos/sun-tree-forest-nature-light-5169796/ (dmarr515)
https://search.creativecommons.org/photos/d235c7ac-b922-4c9a-986f-632a73dacbd9 (Miguel Vera)
1
sustained by the perpetual throughflow of energy. In this process, numerous
conversions, transfers and exchanges of energy and matter take place. Within each
biological community, there exists a multitude of relationships, and within every
ecosystem, countless interactions occur (Miller & Spoolman, 2018). The latest
development toward a functional typology for the world's ecosystems, by the
International Union for Conservation of Nature (IUCN), include 'realms' at the top of
the hierarchical structure followed by biomes and ecosystem types (Keith et al., 2020).
Look at the image of the penguins living at Boulder's Beach. Consider how this is a
local snapshot of a biological community within a coastal ecosystem in which living
organisms interact with each other and their non-living environment. South Africa is
characterised by five major realms and several hundreds of ecosystems (SANBI,
2019). The status of ecosystems is assessed and reported at national and
international levels; for example, by the National Biodiversity Assessments (NBAs)
every five to seven years by SANBI, the United Nations (Sustainable Development
Goals) and the Ramsar Convention (the Convention on Wetlands of International
Importance). Unfortunately, the most recently published National Biodiversity
Assessment of 2018 (SANBI, 2019) reported that nearly half of the more than 1 000
different types of ecosystems that they assessed are threatened. Wetlands were found
to be the most threatened ecosystems of South Africa, similar to global trends in
ecosystem threats in the latest assessment reported on by the Intergovernmental
Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES, 2019).
Habitat loss is one of the major contributing threats. This is not only devastating to the
natural environment but also to humans and our well-being. Our biological diversity
provides the key to Earth's life-support systems, which drive the ecosystem services
that benefit humans (Ntshane & Gambiza, 2016). Research by Turpie et al. (2017)
values South Africa's ecosystem services at an estimated R275 billion per year. This
value lies not only in direct income and market-related factors but also in non-market
benefits to humans.
In this learning unit, the biological organisation of life on Earth, the composition and
functioning of ecosystems, the cycling of energy and matter, and the impact of human
activities on all of these will be studied. Bear in mind what you have already learned
about matter and energy and the fact that they can be changed but never created or
destroyed. You will soon see that there is no ''away'' in ecosystems. You will also see
that the second law of thermodynamics is crucial in the flow of energy through
ecosystems and that the organisation and interactions in the system are determined
by this law. The learning unit also continues your introduction to maps and geographic
tools by reflecting on different types of maps and how they are read and interpreted.
2
EXTRACT FROM THE EXPERTS
Dr Heidi van Deventer, senior researcher from the Council for Scientific
& Industrial Research (CSIR) and Extraordinary Research Associate to
the Department of Geography, GeoInformatics and Meteorology at the
University of Pretoria writes:
Curbing further degradation of our ecosystems and restoration
of key ecosystems are critical to undertake as recommended by
the United Nations in their ''Decade on Ecosystem Restoration.
Each person has to make their contribution – see
https://www.decadeonrestoration.org/ for more information.
3.2 AIM AND LEARNING OUTCOMES
This learning unit aims to expose you to how ecosystems function and how matter and
energy flow through them in the interactions and relationships between living and nonliving things. Since you learned about maps and their importance in the previous
learning unit, this learning unit will explain how maps are read and interpreted. Once
you have completed this learning unit, you can use the outcomes to assess the quality
of your learning experience. Assess whether you meet each aim and outcome with
confidence. If not, you are advised to dedicate more time to those you are still having
trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:





Identify and describe the biological organisation of life on Earth.
Describe how energy enters ecosystems through photosynthesis.
Define what ecosystems are and how energy flows through them.
Identify the various components that make up an ecosystem.
Analyse what happens to matter in an ecosystem and explain the different
biogeochemical cycles.
 Understand the role of soil in ecosystems and how it is formed.
 Identify, read and interpret different types of maps.
3.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from three
prescribed open-access books.
3
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.

o
Chapter 2: Matter, Energy, & Life
2.4: Energy Enters Ecosystems Through Photosynthesis

o
o
Chapter 3: Ecosystems and the Biosphere
3.1: Energy Flow through Ecosystems
3.2: Biogeochemical Cycles

o
Chapter 9: Conventional & Sustainable Agriculture
9.1: Soil Profiles & Processes
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.

o
Chapter 1: Introduction to Environmental Science
1.3: Biological Organization
Theis, T. & Tomkin, J. (Editors). 2018. Sustainability: A Comprehensive
Foundation. OpenStax CNX. Available at:
https://legacy.cnx.org/content/col11325/latest/pdf.

o
o
Chapter 4: Biosphere
4.1: Biosphere – Chapter Introduction
4.2: Biogeochemical Cycles and the Flow of Energy in the Earth
System
This table summarises the study material for this learning unit.
Prescribed material
Zehnder et al.,
2018
Chapter 1
Fisher,
2018
Chapters 2, 3 & 9
Relevant sections
2.4, 3.1, 3.2 and 9.1
1.3
4
Theis & Tomkin,
2018
Chapter 4
4.1 and 4.2
3.4 KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 3.2 and will help you to find your way through the study material.
3.4.1 The biological organisation of life on Earth
Study chapter 1.3 in Zehnder et al. (2018).
Summary

All living things are made of cells (the smallest fundamental unit of structure
and function in living organisms). The cells of most organisms contain
organelles that provide the specific functions of cells.

Organisms are individual living entities. All living organisms are highly
organised, require energy, grow over time and respond to their environment.

A population is a group of individuals of the same species living within a
particular area. Populations fluctuate based on factors such as seasonal
changes and natural disasters.

A community consists of two or more populations of different species living
in a particular area. Competition for limited resources such as sunlight or
nutrients occurs in communities both within species and among different
species.
3.4.2 What is photosynthesis and how does
energy enter ecosystems through this
process?
Study chapter 2.4 in Fisher (2018) and chapter
1.3 in Zehnder et al. (2018).
Summary
 Through photosynthesis, certain organisms convert solar energy (sunlight) into
chemical energy, which is used to build carbohydrate molecules. This chemical
energy is what cells run on and need to perform work and it is released when
an organism breaks down food.
 Photosynthesis requires sunlight, carbon dioxide and water to release oxygen
and carbohydrate molecules, most commonly glucose. It takes place in two
stages, namely (1) light-dependent reactions where chlorophyll absorbs solar
energy and converts it into chemical energy with the aid of water after which it
releases oxygen; and (2) the Calvin cycle where the chemical energy from the
first stage drives the capture of carbon from carbon dioxide and produces
carbohydrate molecules.
5




The energy harnessed from photosynthesis continuously enters the
ecosystems on Earth and is transferred from organism to organism. Therefore,
this process provides most of the energy required by living things on Earth.
Autotrophs are organisms that can produce their own food through
photosynthesis (including plants and certain types of bacteria and algae).
Plants are photoautotrophs (a type of autotroph that uses sunlight and carbon
to synthesise chemical energy).
Heterotrophs are organisms that cannot carry out photosynthesis and must
obtain energy and carbon by consuming other organisms (for example, animals
and fungi).
Photosynthesis is important to the biosphere for the following three reasons: (1)
it creates oxygen; (2) it provides energy for nearly all ecosystems; and (3) it
provides the carbon needed for organic molecules.
ACTIVITY 3.1: EXPLORING AN ECOSYSTEM NEAR ME
Instructions
 Visit an ecosystem in your area or region. For example, a nearby wetland, a
forest, a beach, a lake or a river, just to name a few.
 Spend some time observing and identify the different living (biotic) and nonliving (abiotic) components within this ecosystem. You might want to take
some photos. Identify the ecosystem's major autotrophs and heterotrophs
and write them down.
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 3.1: Exploring Ecosystems near Me"
by following the task outlined below.
Purpose
To assist you in discovering ecosystems and how ecosystems consist of various
interconnected components. This will expand your practical knowledge, not only
about ecosystems in general but also about your local area or region.
Task
In your blog post, share with fellow students:
1. the ecosystem you explored,
2. the list of living and non-living components of that ecosystem, and
3. the list of autotrophs and heterotrophs within that ecosystem.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
3.4.3 What are ecosystems and how does energy flow through them?
Study chapter 3.1 in Fisher (2018), chapter 4.1 in Theis and Tomkin (2018) and
chapter 1.3 in Zehnder et al. (2018).
6
Summary
 An ecosystem is a community of organisms (biotic) and their non-living (abiotic)
environment.
 Based on their general environment, ecosystems are classified into three broad
categories, namely (1) freshwater, (2) marine and (3) terrestrial ecosystems.
Individual ecosystem types within these categories vary based on their
environmental habitat and organisms. As mentioned in section 1, the most
recent typology by the IUCN suggests five 'realms' at the top of the hierarchical
structure namely the terrestrial, subterranean, marine, freshwater and
atmospheric realms.
 Terrestrial ecosystems are subdivided into larger regions called biomes.
Biomes are large-scale communities of organisms defined primarily by
dominant plant types and climatic conditions. Examples include tropical
rainforests, deserts and grasslands.
 The biosphere is the collection of all ecosystems and represents the zones of
life on Earth. The biosphere is at the highest level of biological organisation and
includes land, water and even the atmosphere to a certain extent.
 Ecosystems provide ecosystem services that are critical to human well-being
and survival. These include (1) provisioning ecosystem services such as food
and water, (2) regulating ecosystem services (the processes) on Earth that
control Earth's key physical and biological elements such as climate regulation
and air and water purification, (3) cultural ecosystem services that reflect the
aesthetic and spiritual values humans place on nature such as recreational
activities, and (4) supporting ecosystem services that are the biogeochemical
cycles that drive the functioning of ecosystems.

A food chain is a linear sequence of organisms through which nutrients and
energy pass as one organism feeds on another. Producers, high-level
consumers and decomposers form the different levels of a food chain. An
organism's position in a food chain or web is called a trophic (energy) level.
o Producers are photosynthetic organisms.
o Primary consumers are organisms that are herbivores and consume
producers.
o Secondary consumers are carnivores that feed on primary consumers while
tertiary consumers are carnivores who feed on other carnivores. Higherlevel consumers feed on the lower trophic levels up to the organisms at the
top of the food chain.
o Decomposers break down dead and decaying organisms.
o Detritivores consume organic detritus.
 Energy is lost as heat at and between each trophic level.
 Food chains are an overly simplistic representation of ecosystems since some
organisms feed at more than just one trophic level. Species feed on and are
eaten by more than just one species.
7





A food web is a more accurate representation of ecosystems as it accounts for
multiple feeding interactions between each species.
Food web diagrams illustrate how energy flows through ecosystems including
how organisms acquire energy, use it and how much remains for use by other
organisms in the food web.
As described in the previous section, energy is acquired by living components
in ecosystems in two ways, namely (1) autotrophs that harness light
(photoautotrophs) or chemical energy (chemoautotrophs) and (2) heterotrophs
that acquire energy by consuming other organisms.
Gross primary productivity is the rate at which photosynthetic producers
incorporate energy from the sun. Net primary productivity is the remaining
energy from producers after metabolism and heat loss (gross primary
productivity minus the rate at which producers use this chemical energy through
aerobic respiration).
Ecosystems are subject to various pressures including changes in the
environment from natural processes. Succession refers to the natural process
in which plant and animal communities are replaced in a particular area over
time. Humans also disturb ecosystem dynamics directly; for example,
biomagnification, which is the increasing concentration of persistent, toxic
substances in organisms at each successive trophic level.
ACTIVITY 3.2: ECOSYSTEM SERVICES
Task
Look at the image of the Chobe River. Reflect on which of the four major types of
ecosystem services are captured here and why.
Cruise on the Chobe River (Source: Creative Commons, Chris Parker, 2012)
Purpose
To assist you in identifying the different ways in which humans benefit from
ecosystem services. This will expand your knowledge of the importance of
ecosystems.
8
3.4.4 What happens to matter in an ecosystem?
Study chapter 3.2 in Fisher (2018) and chapter 4.2 in Theis and Tomkin (2018).
Summary
 The six most common elements associated with organic molecules (carbon,
nitrogen, hydrogen, oxygen, phosphorus and sulphur) take a variety of chemical
forms in ecosystems (these either exist in the atmosphere, on land, in water or
beneath Earth's surface). Each element is used by organisms in a variety of
ways.
 The cycling of inorganic matter (elements and molecules) between living and
non-living components of ecosystems are called biogeochemical cycles. This
cycling of elements is also interconnected. Today, human activities are
significantly altering these biogeochemical cycles.
 Biogeochemical cycles include the following:
o Water cycle
The hydrosphere is the area of Earth where water movement and storage
occur as liquid surface water (e.g., rivers and lakes), beneath the surface
(groundwater), ice (e.g., polar ice caps and glaciers) and as water vapour
in the atmosphere.
The water cycle is driven by the sun's energy and includes various
processes such as evaporation, condensation, precipitation and surface
runoff.
Less than one per cent of the water on Earth is readily available to use as
fresh water in lakes and rivers. Most of the water on Earth is salty ocean
water. Groundwater is a significant source of fresh water found below
Earth's surface. Groundwater reservoirs, called aquifers, are a significant
source of drinking and irrigation water; however, human activities such as
agriculture causes the overuse of groundwater, which is in turn leading to
aquifer depletion.
o Carbon cycle
In terms of mass, carbon is the second most abundant element in
organisms. All organic molecules consist of carbon. Most of Earth's carbon
is stored in sedimentary rocks. Atmospheric carbon in the form of carbon
dioxide is significant because it is a greenhouse gas.
The carbon cycle can be studied as two interconnected sub-cycles, namely
(1) the rapid carbon exchange among living organisms in what is called the
biological/natural carbon cycle (for example, the process of photosynthesis
and respiration) and (2) the long-term cycling of carbon through geological
processes called the biogeochemical carbon cycle (for example, the
complex movement of carbon through land, water and air).
o Nitrogen cycle
Most nitrogen, which is held in rocks, does not play a major role in the
nitrogen cycle. The second-largest pool of nitrogen is in the form of nitrogen
gas. While nitrogen makes up around 78 per cent of the atmosphere, it is
9
o
o
inert and cannot be readily absorbed by living organisms. Symbiotic
bacteria incorporate nitrogen into their organic molecules through
biochemical processes such as nitrogen fixation whereby nitrogen can
enter living organisms. Nitrogen gas is converted into ammonia
(ammonification or mineralisation), which is then transformed into
ammonium. Bacteria convert ammonium into nitrites and nitrates from
where it can finally be used by producers.
Human activity impacts the nitrogen cycle through the process of
combustion where nitrogen oxides are formed and through artificial
fertilisers that cause, amongst others, eutrophication from nutrient runoff
that causes excessive algae growth in saltwater and freshwater, and the
depletion of oxygen.
Phosphorus cycle
Phosphorus is an essential nutrient for living processes and is often a
limiting nutrient in aquatic ecosystems. It occurs naturally as phosphate.
Phosphate movement through the ocean, land and soil is a very slow
process. Excessive phosphorus, just as with excessive nitrogen, may also
enter ecosystems through fertiliser runoff that depletes oxygen in water
bodies such as oceans and lakes and causes dead zones where these
bodies are stripped of their normal flora and fauna.
Sulphur cycle
Sulphur forms an essential part of the molecules of living organisms. It is
an element that forms part of amino acids, which is essential in protein
formation.
Sulphur cycles between the oceans, land and atmosphere. Atmospheric
sulphur is found in the form of sulphur dioxide (and sulphate aerosols) while
on land, ecosystems can use soil sulphates.
Human activity impacts the sulphur cycle through the burning of fossil fuels
containing trace amounts of sulphur, which releases sulphur dioxide and
hydrogen sulphide into the atmosphere and contributes to the formation of
corrosive acid rain that causes damage to ecosystems.
INTRODUCING GEOGRAPHIC TOOLS AND MAPS
Reading and interpreting maps
Maps are an important tool for a geographer to explain spatial phenomena. You
need the following skills to read and interpret a map:
 Locational skills to locate yourself on a map using grid reference, coordinates
and know what longitude and latitude are. Watch the following video:
https://www.youtube.com/watch?v=swKBi6hHHMA.
 You need to understand map projections, which is used to transpose Earth
on
a
flat
piece
of
paper.
Watch
the
following
video:
https://www.youtube.com/watch?v=nJ5r4HJMrfo.
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
You need to understand map scales to determine distances and areas such
as the size of a farm. For map scales, watch the following video:
https://www.youtube.com/watch?v=K3aM0H7j_Jg.
 You need to interpret the data presented to you in a map for extracting
information and make comparisons. Watch the following video:
https://www.youtube.com/watch?v=VgeMUpK-qXM.
 You need to use a legend to understand and interpret different map symbols.
Map symbols
Map symbols are graphic marks to encode thematic information on a map. These
simplified representations of the environment come in a variety of forms.
Map symbols use the following four basic properties:
o Colour
For example, using blue to depict a river or a lake; green for open spaces or
agriculture; red, dark brown and blue lines for road types; and thin brown lines to
depict contour lines.
o Shapes
Geometric symbols – commonly used, abstract map symbols that do not resemble
the phenomenon being mapped such as lines, points, areas, circles and triangles.
Triangles are used to depict trigonometric beacons on a topographic map. Points
are used on small-scale maps to depict cities, towns and villages.
Irregular shaped symbols – area symbols that show the boundaries of a country, the
shape of a building, the shape of a field or a lake.
Pictographic symbols – map symbols that resemble the mapped phenomena and
enable the map reader to understand the map without a legend such as tourist maps
using knives and forks to depict restaurants, a building with five pillars depicting a
courthouse, and an open book showing the location of a library. Some pictographic
symbols can be cartoon-like as shown on the Cape Town tourist map below.
o Size
As illustrated above, points are used on a small-scale map to depict cities, towns
and villages and the size of the point is used to distinguish between them. Points
showing cities are larger than the points showing the locations of towns and villages
are depicted by points much smaller than those showing towns.
o Orientation
Short lines are used to indicate embankments, cuttings, dumps and excavation
sites. To distinguish between these, you need to look at the orientation of the lines.
For example, embankment dump the lines point outwards whereas cutting and
excavation site lines point inwards.
The choice of map symbols is governed by the purpose, the scale and the type of
map.
A political map provides an overview of a country's political boundaries,
administrative units (such as provinces and municipalities), major road and rail
networks, seaports, major airports, border posts, and so forth. Political maps are,
in general, small-scale maps.
The political map below uses points to show towns in South Africa. Look at the
map legend to see the different town types. The same is true for the different line
symbols used on this map.
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Political map of South Africa (Source:
https://www.nationsonline.org/oneworld/map/south_africa_map.htm)
A tourist map (below) is a medium- to large-scale, special-purpose map using
pictographic symbols to show various attractions in a place or region such as the
tourist map of the Cape Town Peninsula.
Tourist map of Cape Town Peninsula (Source: https://ashanti.co.za/wpcontent/uploads/2015/02/Cape-Town-Birds-Eye-View-Map.jpg)
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The purpose of a topographic map, according to National Geo-Spatial
Information (NGI), is to accurately depict the location of man-made features using
symbols and colour. Spot heights and contours at 20-meter intervals show the
topography of the area mapped. It is a general-purpose map containing
information for planning and decision making and navigation. The topographic
map below uses a standard set of map symbols for ease of use and apply to
every topographic map used in South Africa.
Topographic map of Pietermaritzburg (Source:
https://www.avenzamaps.com/maps/410193/2930cb-pietermaritzburg)
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3.4.5 What is soil and what part does it play in ecosystems?
Study chapter 9.1 in Fisher (2018).
Summary
 Soil consists of mineral matter, organic matter
(humus) and living organisms, while water and air fill
its pores.
 Soil is defined differently across disciplines.
Commonly, for example in agriculture, soil is the oneto two-meter-thick medium for plant growth while in
civil engineering, it includes all the material except the
bedrock. Paleosols, or ancient soils that are
sometimes found subsurface, inform us of historic
climatic and environmental conditions.
 Soil is a critical component for terrestrial ecosystems, plays a role in nearly all
biogeochemical cycles and is the foundation of agriculture and forestry.
 Soil is formed into distinct layers (horizons). The upper horizons (A and O
horizons) are rich in organic material and important for plant growth while the
lower horizons (B and C horizons) retain more original features of the bedrock.
 The formation of soil is affected by the following five fundamental factors:
 Climate
Temperature and precipitation are aspects of climate that determine the
characteristics of soils in particular areas. For example, in warm tropical
areas, soils are thicker.
 Organisms
Animals, plants and microorganisms play an important role in soil
development as they provide a supply of organic matter and/or play a role
in nutrient cycling. Worms and some other organisms, for example, help to
mix, blend, aerate and lighten the soil while plants provide organic matter
to soil (for example, trees that drop leaves) and help to recycle nutrients
with root uptake.
 Relief (topography and drainage)
The relief of an area determines how soil forms there. Local topography can
have important microclimatic effects and determine soil erosion rates. For
example, steep slopes have more soil erosion and water runoff, which leads
to limited soil formation. Soil drainage determines local vegetation types
and affects the accumulation and preservation of organic matter.
 Parent material
Parent material refers to the material from which soil has developed and
determines the soil type. Weathering deepens, mixes and alters the soil
through chemical, physical and biological processes over time. The type of
parent material also affects the rapidity of soil development as some are
more weatherable than others.
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 Time
With time, soils tend to become thicker, more developed and more altered.
The rate of change is greater for soils in youthful stages of development,
which slows with time until it approaches a condition of equilibrium. Soil
formation is impacted by different factors and processes over time such as
geological events like landslides.
THE GROUND BENEATH YOUR FEET
Instructions
 Watch the following video: https://www.youtube.com/watch?v=cLk9pyrkKas
(1:00 minute)
Purpose
 The video "Soil - what you don't know about the ground beneath your feet" is
a short and insightful video on the significance of the ground beneath our
feet. In other words, why soil is important to us and Earth's ecosystems.
3.5 CAPSTONE ACTIVITY
LEARNING UNIT 3: CAPSTONE ACTIVITY
Instructions
 Go to the Discussions tool on the GGH1503 module site.
 Go to the topic entitled Learning Unit 3: Capstone Activity.
 Reply by providing your response on the tasks detailed below.
Purpose
To apply the knowledge you have acquired in respect to ecosystems, basic map
elements and the reading and interpreting of different maps. It equips you to meet
the first of the module's three main learning outcomes (as listed in the module
overview) by providing you with the opportunity to explore the complexities of the
natural environment using geographical tools.
Task instructions
For this activity, you will need to consult the map on the following page and respond
to the tasks below.
Task
1. What do you think is being represented in the map and to which one of the
IUCN's realms does this feature belong?
2. List the basic map elements that are (a) included in this map and (b) missing
from this map.
3. Which of the four basic map symbol properties are used in this map?
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(Source: Anisha Dayaram, SANBI)
3.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
3.6.1 List the three reasons why photosynthesis is important to the biosphere and
ecosystems.
3.6.2 How does the second law of thermodynamics apply to the way that energy
flows in an ecosystem?
3.6.3 Describe the process of eutrophication.
3.6.4 Air and water purification are examples of … ecosystem services.
A. provisioning
B. cultural
C. regulating
D. supporting
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3.6.5 What would happen to ecosystems if all the soil on Earth disappeared? List
your ideas.
3.7 CONCLUSION
Upon completion of this learning unit, you should understand that energy enters
ecosystems through photosynthesis and flows through the various components of
ecosystems. You should also be familiar with the flow of matter in ecosystems through
various biogeochemical cycles. Human activities continue to significantly impact these
flows. In this learning unit, you have gained greater knowledge on how ecosystems
are sustained by natural processes and ecosystem components without which Earth
cannot function. What do ecosystems mean for you, both directly and indirectly? Can
you think of particular ecosystem services that you benefit from? Now that you have
reached the end of learning unit 3, you may proceed to learning unit 4.
3.8 REFERENCES
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services
(IPBES). 2019. Summary for policymakers of the global assessment report on
biodiversity and ecosystem services of the Intergovernmental Science-Policy
Platform on Biodiversity and Ecosystem Services. Díaz, S., Settele, J., Brondízio,
E.S., Ngo, H.T., Guèze, M., Agard, J., Arneth, A., Balvanera, P., Brauman, K.A.,
Butchart, S.H.M., Chan, K.M.A., Garibaldi, L.A., Ichii, K., Liu, J., Subramanian, S.M.,
Midgley, G.F., Miloslavich, P., Molnár, Z., Obura, D., Pfaff, A., Polasky, S., Purvis,
A., Razzaque, J., Reyers, B., Chowdhury, R.R., Shin, Y.J., Visseren-Hamakers, I.J.,
Willis, K.J. & Zayas, C.N. (eds.), IPBES secretariat, Bonn, Germany, 56 pp. DOI:
https://doi.org/10.5281/zenodo.3553579.
Keith, D.A., Ferrer, J.R., Nicholson, E., Bishop, M.J., Polidoro, B.A., Ramirez-Llodra,
E., Tozer, M.G., Nel, J.L., MacNally, R., Gregr, E.J., Watermeyer, K.E., Essl, F.,
Faber-Langendoen, D., Franklin, J., Lehmann, C.E.R., Etter, A., Roux, D.J., Stark,
J.S., Rowland, J.A., Brummitt, N.A., Fernandez-Arcaya, U.C., Suthers, I.M., Wiser,
S.K., Donohue, I., Jackson, L.J., Pennington, R.T., Pettorelli, N., Andrade, A.,
Kontula, T., Lindgaard, A., Tahvanainan, T., Terauds, A., Venter, O., Watson, J.E.M.,
Chadwick, M.A., Murray, N.J., Moat, J., Pliscoff, P., Zager, I., Kingsford, R.T. 2020.
The IUCN Global Ecosystem Typology v1.01: Descriptive profiles for Biomes and
Ecosystem Functional Groups. Available at:
https://iucnrle.org/static/media/uploads/references/researchdevelopment/keith_etal_iucnglobalecosystemtypology_v1.01.pdf.
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Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Ntshane, B.C. & Gambiza, J. 2016. Habitat assessment for ecosystem services in
South Africa. International Journal of Biodiversity Science, Ecosystem Services &
Management, 12(4): 242-254.
South African National Biodiversity Institute (SANBI). 2019. National Biodiversity
Assessment 2018: The status of South Africa's ecosystems and biodiversity.
Synthesis Report. South African National Biodiversity Institute, an entity of the
Department of Environment, Forestry and Fisheries, Pretoria. pp. 1–214. Available
at: https://www.sanbi.org/wp-content/uploads/2019/10/NBA-Report-2019.pdf.
Theis, T. & Tomkin, J. (Editors). 2018. Sustainability: A Comprehensive Foundation.
OpenStax CNX. Available at: https://legacy.cnx.org/content/col11325/latest/pdf.
Turpie, J.K., Forsythe, K.J., Knowles, A., Blignaut, J. & Letley, G. 2017. Mapping and
valuation of South Africa's ecosystem services: A local perspective. Ecosystem
services, 27:179-192.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
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GGH1503
Learning Unit 4
BIODIVERSITY AND EVOLUTION
Contents
4.1
INTRODUCTION ........................................................................................................ 1
4.2
AIM AND LEARNING OUTCOMES ........................................................................... 3
4.3
PRESCRIBED MATERIAL......................................................................................... 4
4.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 4
4.4.1
Introducing biodiversity and life on Earth ....................................................... 5
4.4.2
The origin of biodiversity and where species come from .............................. 6
4.4.3
What is biodiversity and why is it important? ................................................. 7
4.4.4
Threats to biodiversity ...................................................................................... 8
4.4.5
Preserving biodiversity ................................................................................... 11
4.5
CAPSTONE ACTIVITY ............................................................................................ 13
4.6
SELF-TEST .............................................................................................................. 14
4.7
CONCLUSION ......................................................................................................... 15
4.8
REFERENCES ......................................................................................................... 15
LEARNING UNIT 4
BIODIVERSITY AND EVOLUTION
Author: Ruan Schoeman
Co-author: Leani de Vries
Academic editor: Kristy Langerman
1
Clear-cutting of a forest in Tasmania (Source: Unsplash.com, Matt Palmer)
"We should care about and avoid degrading the earth's biodiversity because it is vital
to maintaining the natural capital that keeps us alive and supports our economies.
We use biodiversity as a source of food, medicine, building materials, and fuel."
(Miller & Spoolman, 2018:80)
4.1 INTRODUCTION
The Earth is a unique place given the existence of life. But why is there life on Earth?
Where and when and how did life emerge? How has it changed since then? Why has
it changed? Why is it so diverse? The material from this learning unit will assist you in
attempting to answer some of these questions.
No one can say with certainty how life started. There are hypotheses and theories as
well as ideologies and beliefs about this. In this module, we are not going to argue the
1
All images used in this learning unit are from free, publicly accessible sources.
https://unsplash.com/photos/BtleFKDvN2Q (Matt Palmer)
https://search.creativecommons.org/photos/611ea69a-b39c-4845-be7e-db0e539ca944 (NIAID)
https://search.creativecommons.org/photos/4da2ca41-5146-40cc-8b2e-1f5ca08c20d8 (subarcticmike)
https://search.creativecommons.org/photos/5ac5c860-1e7a-45b1-8825-4c875db78ec4 (MyFWC Florida Fish and Wildlife)
1
point, but some of the evidence that scientists use to build theories as well as the
mainstream of modern scientific thinking will be presented in this learning unit. While
we know little about the very beginnings of life, we have come to learn more about the
changes and adaptations (also called evolution) life has undergone over the last few
billion years to result in the rich diversity of the present time. There are, for example,
an estimated seven to 100 million species on Earth that vary greatly in their
characteristics and ecological roles (Miller & Spoolman, 2018).
Biological diversity, or biodiversity for short, refers to the variety of life on Earth and is
vital in maintaining Earth's natural capital, keeping us alive, and supporting our
economies (Miller & Spoolman, 2018). Initiatives such as the Convention on Biological
Diversity (CBD) and the Convention on International Trade in Endangered Species of
Wild Fauna and Flora (CITES), aim to develop measures for protecting biodiversity
through conservation, sustainable use, and fair and equitable sharing of its benefits.
However, throughout the world, the benefits we enjoy from biodiversity are under
threat. Africa obtains particular value from its rich biocultural diversity and is impacted
by changes in biodiversity. The continent is increasingly threatened by both
anthropogenic drivers (such as habitat degradation and land use) as well as natural
drivers of biodiversity decline (such as diseases and natural disasters). Africa is also
particularly vulnerable to climate change, which is likely to exacerbate future changes
to biodiversity; for example, the distribution and population sizes of Africa's plant
species that are critical for the continent's food security (Archer et al., 2021).
Despite these concerns, Siddig (2019) points to a lack of standardised data to assess
and monitor Africa's biodiversity in what he calls a 'decades-long African biodiversity
knowledge gap'. To address current and future biodiversity threats, we need reliable
biodiversity information and accountability from all stakeholders. Biodiversity
conservation does not only concern policymakers, local communities and researchers
at the forefront, but even private businesses (Makina & Luthuli, 2014; Smith et al.,
2020). Think of the image on the previous page of a commercial forest subject to clearcutting. Forests hold immense economic value and the harvesting of wood for timber
and paper is one of the largest global industries. However, these commercial activities
have harmful consequences such as topsoil erosion, sediment runoff, habitat loss and
ultimately a loss in biodiversity (Miller & Spoolman, 2018).
2
INDIGENOUS KNOWLEDGE SYSTEMS AND ITS KEY ROLE
IN UNDERSTANDING OUR LIVING EARTH
What does Indigenous knowledge mean for biodiversity?
Watch the following videos:
•
https://youtu.be/-a7vvFxKfTY (2:08 minutes)
•
https://www.dw.com/en/indigenous-knowledge-and-biodiversityconservation/av-52415971 (6:36 minutes)
Read the following article:
•
https://www.unep.org/news-and-stories/story/indigenous-peoplesand-nature-they-protect
4.2 AIM AND LEARNING OUTCOMES
This learning unit aims to expose you to how life on Earth is organised and structured,
where Earth's biodiversity comes from, and how and why it changes. The learning unit
also takes you through the importance of biodiversity, including some of the core
threats to biodiversity, and some of the measures to preserving biodiversity. Once you
have completed this learning unit, you can use the outcomes to assess the quality of
your learning experience. Assess whether you meet each aim and outcome with
confidence. If not, you are advised to dedicate more time to those you are still having
trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:
• Recognise the levels of organisation of life on Earth.
• Identify the key characteristics of the three domains under which all life forms are
classified.
• Explain how species evolve through natural selection.
• Define biodiversity and the different types of measures of biodiversity.
• Describe the importance of biodiversity to human populations.
• Define biodiversity loss.
• Identify and explain the variety of threats to biodiversity.
• Explain extinction and the consequences of species going extinct.
• Elaborate on some examples of human efforts to preserving biodiversity.
3
4.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from two prescribed
open-access books.
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
•
o
o
o
o
o
Chapter 5: Conservation & Biodiversity
5.1: Introduction to Biodiversity
5.2: Origin of Biodiversity
5.3: Importance of Biodiversity
5.4: Threats to Biodiversity
5.5: Preserving Biodiversity
Theis, T. & Tomkin, J. (Editors). 2018. Sustainability: A Comprehensive
Foundation. OpenStax CNX. Available at:
https://legacy.cnx.org/content/col11325/latest/pdf.
•
o
o
o
Chapter 4.3: Biodiversity, Species Loss, and Ecosystem Function
4.3.2: What is Biodiversity?
4.3.3: Current Trends: Species Loss and Decline
4.3.5: Species and Ecosystem Loss in Perspective
This table summarises the study material for this learning unit.
Relevant sections
Prescribed material
Fisher,
Theis & Tomkin,
2018
2018
Chapter 5
Chapter 4.3
5.1, 5.2, 5.3, 5.4 and
4.3.2, 4.3.3 and 4.3.5
5.5
4.4 KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 4.2 and will help you to find your way through the study material.
4
4.4.1 Introducing biodiversity and life on Earth
Study chapter 5.1 in Fisher (2018).
Summary
• All living things are highly complex, organised,
structured and are made of one or more cells
(cell theory states that the cell is the basic unit
of life). There are many types of cells with
different functions; however, they are grouped
into two broad categories. Prokaryotic cells (e.g. bacteria) are simple, singlecelled organisms that lack a nucleus or any other membrane-bound organelles
while eukaryotic cells (e.g. animal and plant cells) have a membrane-bound
nucleus and other membrane-bound organelles.
• An organism refers to an individual living entity.
• Earth is home to an array of life forms, from single-celled (unicellular) organisms
to organisms with more than one, even trillions of cells (multicellular).
• The plethora of organisms on Earth are either prokaryotic or eukaryotic.
• Biologists classify, group and name organisms based on the similarities in
morphology and genetics. This is called taxonomy. Taxonomists group
organisms into categories (domain being the broadest, and species and
subspecies being the most specific). All life forms are classified under three
recognised domains namely Bacteria, Archaea and Eukarya.
• Domain Bacteria are incredibly abundant and include prokaryotic, unicellular
organisms found in virtually every habitat. Although bacteria are mostly seen
as disease-causing organisms, most species are either benign or beneficial to
humans.
• Bacteria are well-known for their metabolic diversity. The complex
biochemistry that occurs inside of cells is called metabolism.
• Many bacterial species are called autotrophs (create their own food using
photosynthesis – the process that converts light energy into chemical
energy). Cyanobacteria is an ecologically important group of photosynthetic
bacteria that play important roles in the food webs of aquatic systems.
• Heterotrophic bacteria can only obtain food through eating other organisms
(it includes bacteria that cause disease in humans but most are harmless
to humans). Beyond the human body, heterotrophic bacteria play important
roles in ecosystems (such as soil bacteria that assist in decomposing living
matter to release nutrients for plants).
• Domain Archaea are unicellular and prokaryotic organisms. At first, they appear
a lot like bacteria, but recent DNA analysis has deemed them so genetically
different that they belong in their own domain.
• Archaean species can be found in some of the most inhospitable
environments such as the bottom of the ocean or geothermal springs.
Organisms that can tolerate and thrive under such severe circumstances
5
are called extremophiles. A large percentage of archaeans are
extremophiles, which suggests that they may be descendants of some of
the most ancient forms of life on Earth.
• Domain Eukarya is the most familiar to us as it includes plants, animals, fungi
and protists. The domain is categorised by the presence of eukaryotic cells and
is divided into different kingdoms.
• Kingdom Animalia comprises multicellular, heterotrophic organisms such as
humans. Kingdom Plantae includes multicellular, autotrophic (except for a few
parasite species) organisms (such as trees). Kingdom Fungi (such as yeast)
includes multicellular and unicellular heterotrophic fungi. While fundamentally
different, fungi are mistaken for plants, yet they do not perform photosynthesis
and feed on the living matter of others. Protists (such as kelp and seaweed) is
a disparate group of very diverse unicellular, multicellular, autotrophic and
heterotrophic organisms that was formerly its own kingdom until recent analysis
indicated it should be split into many kingdoms.
4.4.2 The origin of biodiversity and where species come from
Study chapter 5.2 in Fisher (2018).
Summary
• All species have, at some point, evolved from a different species.
• Evolution is the ongoing process through which the characteristics of a species
change over time, which can ultimately cause new species to arise (speciation).
Evolution is a unifying theory of biology and the overarching framework within
which biologists ask questions about the living world.
• The mechanism for how species can change over time is described by the
theory of evolution by natural selection. Species change was already suggested
and debated well before Charles Darwin and Alfred Russel Wallace (the
naturalists credited with the theory of natural selection from their expeditions to
the tropics) with the writings of Plato and ideas of the ancient Greeks.
• Darwin coined the mechanism called natural selection to explain why he
observed species of organisms on different islands that were similar yet had
distinct differences. It was reasoned that offspring with inherited characteristics,
which allow them to best compete for limited resources, will survive and have
more offspring than those individuals with variations that are less able to
compete. These traits will be better represented in the next generation. This will
lead to a change in population over generations because of a process that
Darwin called "descent with modification''.
• In summary, natural selection can be defined as the process that causes
beneficial traits to become more common in a population over time, causing the
population to evolve. Natural selection can only take place if there is variation
in a population. These variations must have some genetic basis (a way for
those traits to be passed down); otherwise, natural selection would not lead to
change in the next generation.
6
•
•
Genetic diversity in a population can only result from either mutation
(permanent change in DNA sequence) or sexual reproduction.
Without a difference in traits, nature would not be able to select the traits that
are best adapted for organisms' environments at a particular time.
NATURAL SELECTION AND PENGUIN SPECIES
Instructions
• Watch the following video:
https://www.washington.edu/news/2016/09/23/how-natural-selection-actedon-one-penguin-species-over-the-past-quarter-century/ (1:05 minutes)
Purpose
• The video "How natural selection acted on one penguin species over the past
quarter century" presents interesting and recent research, from the University
of Washington, on the work of natural selection on Earth's species at present.
4.4.3 What is biodiversity and why is it important?
Study chapter 5.3 in Fisher (2018) and chapter 4.3.2 in
Theis and Tomkin (2018).
Summary
• Biologists estimate that species extinctions are
currently between 500 to 1 000 times higher than that
of Earth's history (causing a sharp decline in Earth's
biodiversity in the next century or two). Many
extinctions will include species not even discovered
yet. Species that are classified as endangered are at
high risk of becoming extinct.
•
Biodiversity is the overarching term used for biological variety. Traditionally, and
most commonly, biodiversity is measured by accounting for the number of
species in a location on Earth (species biodiversity). More sophisticated
measures take the number of individuals of each species (relative abundance)
into account. Other measures include genetic diversity (the variety of genes
within a population) and ecosystem diversity (the number of different
ecosystems in an area, or on Earth). Genetic diversity determines species
potential to adapt to changing environments. Ecosystem diversity is needed for
species interactions and biological diversity.
•
Biodiversity loss is the reduction of biodiversity from extinction or displacement.
Much of the loss of biodiversity occurs in highly biodiverse tropical rainforests.
Knowledge of species that inhabit Earth is limited. According to a recent
estimate, only 13% of eukaryotic species have been identified. Given the
•
7
increased pace of species extinction, the scientific community knows little about
what species are being lost. Counting and naming of species is a complex
process whereby biologists determine the unique characteristics that an
organism possesses and whether they belong to any other described species.
•
•
•
•
•
•
•
Biodiversity is not evenly distributed on Earth. Biogeography (ecological,
historical and conservation fields) is the study of the distribution of species on
Earth (both past and present).
Some species, for example, are endemic and are found only in one location.
One of the oldest ecological observations is that biodiversity typically increases
toward the equator (also, there are high numbers of endemic species in the
tropics). Terrestrial hotspots of biodiversity are, however, found on all major
continents.
Biodiversity loss may have great consequences for ecosystems given the
complex interrelations among species. For example, the extinction of one
species may cause the extinction of another.
Biodiversity is important to the survival and welfare of human populations. It
impacts our health and our ability to feed ourselves (through agriculture and the
harvesting of wild food sources).
Examples of human health benefits include the creation of medications from
natural chemicals produced from a diverse group of organisms and
psychological benefits from living in a biodiverse world.
To produce food, humans have been selecting and breeding the best crop
varieties that match their needs since the beginning of agriculture. Our ability to
grow crops depends on the biodiversity of the ecosystems in which they are
grown (e.g., pollination by honeybees). In addition to growing crops and raising
animals for food, humans obtain food from wild populations such as wild fish
catches.
4.4.4 Threats to biodiversity
Study chapter 5.4 in Fisher (2018) and chapter 4.3.3 in Theis and Tomkin (2018).
Summary
• Human population growth and resource consumption are some of the core
threats to Earth's biodiversity (and therefore our own welfare and survival).
• To survive and grow, human populations need natural resources, but most of
these resources are being removed from the environment unsustainably.
•
The introduction of exotic species, overharvesting, and habitat loss are seen as
the greatest proximate threats to biodiversity. Anthropogenic climate change is
also predicted to be a significant cause of extinction.
8
o
Habitat loss
The elimination of habitat (the part of an ecosystem required by a particular
species) leads to the elimination of individuals of that species. Where
humans can rely on technology to modify their environment and make it
habitable, other species cannot. If the entire habitat of a species is
removed, the species will become extinct unless individuals can adapt to
other environments. Human destruction of habitats (such as deforestation)
has accelerated since the last half of the 20th century.
o
Overharvesting
Overharvesting is a large threat to species, especially aquatic species.
Despite the regulation of fisheries (monitored by scientists), there are many
examples of fisheries that have collapsed (like the recent Western Atlantic
cod fishery). Most fisheries are managed as a common resource available
to anyone. Such resources held in common are often subject to
overexploitation. Unsustainable, commercial hunting practices for
bushmeat (wild animals killed for meat) in mostly equatorial Africa and parts
of Asia Bush, are another example of the threat of overharvesting.
o
Invasive species
Exotic species are species that have been intentionally or unintentionally
introduced into an ecosystem in which they did not evolve. The
transportation of people and goods are amongst the causes. While exotic
species may fail because of a low number of individuals introduced or poor
adaptation, some species have characteristics that can make them adapt
successfully to the new ecosystem. When this happens, exotic species
become invasive species, change the ecological conditions of the
ecosystem, and can threaten other species through resource competition
and predation, for example.
o
Climate change
Anthropogenic climate change (from continued greenhouse gas emissions
due to the burning of fossil fuels and deforestation) is a major extinction
threat, especially when combined with other threats like habitat loss.
Scientists predict that climate change alters regional climates, making
habitats less hospitable to resident species and forcing species migrations.
Climate change also impacts delicate timing adaptations of species such
as seasonal food resources and breeding times. A rise in ocean levels due
to the melting of the glaciers is another concern as well as the impact on
the freshwater cycle and freshwater availability.
9
ACTIVITY 4.1: EXOTIC SPECIES AND THEIR THREATS
Instructions
• Look at the image below of an advisory board pointing to an infestation of
Eurasian watermilfoil (a harmful exotic plant species) in a water body.
• Do a basic internet search (or consult a book or any other resource) to learn
about Eurasian watermilfoil, its native geographic distribution and how it acts
as an invasive species outside of its native ranges.
• Go to the Blog tool on the GGH1503 module site.
• Reply to the blog post entitled "Activity 4.1: Exotic Species and their Threats"
by following the task outlined below.
Purpose
To assist you in understanding the threats of exotic species to biodiversity when
they adapt and thrive outside of their native geographic distribution.
Task
In your blog post, share your answers to the following questions with fellow students:
1. What is the scientific (binomial) name of Eurasian watermilfoil?
2. To which continents are Eurasian watermilfoil native and where are they
considered exotic?
3. Explain the characteristics of Eurasian watermilfoil that enable it to act as a
harmful exotic species in aquatic areas (i.e., why and how is it harmful?).
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
Exotic species infestation of water (Source: Creative Commons, Tony Webster)
10
4.4.5 Preserving biodiversity
Study chapter 5.5 in Fisher (2018) and chapters 4.3.3 and 4.3.5 in Theis and
Tomkin (2018).
Summary
• The number of species found on Earth, or in any given geographical area, is
the result of a balance between two ongoing evolutionary processes, namely
speciation and extinction. When speciation rates outstrip extinction rates, the
number of species will increase and vice versa. As reflected in the fossil record,
these rates have fluctuated to a greater and lesser extent throughout the history
of life on Earth (leading to dramatic changes in species numbers).
• Palaeontologists have identified five layers in the fossil record with dramatic
shifts and sudden losses in biodiversity. These events are called mass
extinctions (characterised by more than half of all species disappearing from
the fossil record) and contrast with the relatively constant 'background
extinction rate' over the geologic record. Many lesser extinctions are still
dramatic events. The elimination of species at a local level is known as
extirpation and leads to a threatened or endangered status.
•
•
•
Biologists talk about the ongoing losses of species and ecosystems as the
"biodiversity crisis". Some biologists indicate that we are currently experiencing
a sixth mass extinction event, mostly due to human activities. Numerous recent
extinctions of individual species coincide with the expansion of the European
colonies since the 16th century.
The International Union for Conservation of Nature (IUCN) keeps a list of extinct
and endangered species called the 'Red List of Threatened Species'. This list
is not comprehensive and is of course incomplete. Much more is known about
the state of vertebrates (mammals, birds and amphibians in particular) than any
other forms of animal life, where mostly fish and reptiles have been described
and assessed. Less than two million species thought to exist (mostly insects)
have been described by scientists and of this, only around 45 000 have been
assessed by the IUCN.
Estimates of extinction rates are hampered by the fact that most extinctions
probably happen without being observed. Extinction rates are estimated using
both written records and correlating species loss with habitat loss (through
understanding species-area relationships).
11
•
Some of the main efforts to preserve biodiversity involve legislative approaches
(regulating behaviour), protected areas and habitat restoration.
o
Human behaviour change
Legislation has been enacted to protect species throughout the world.
Legislation includes, for example, international treaties as well as national
laws. The Convention on International Trade in Endangered Species of
Wild Fauna and Flora (CITES) treaty, ratified in 1975, is such a legal
framework for preventing listed species from being taken across national
borders for international trade and prevents their capturing and killing.
o
Conservation in preserves
One of the key tools in conservation efforts is wildlife and ecosystem
preserves. These are areas of land set aside with varying degrees of
protection. However, not all major biomes are protected as preserves. A
biodiversity hotspot refers to a geographical area that contains high
numbers of endemic species and therefore warrants conservation efforts.
Wildlife corridors are strips of land between two preserves to allow species
(and their genes) to move between them. Climate change is predicted to
complicate the location of preserves with species migrations. There are also
controversial consequences to preserves such as when it is followed by the
displacement of indigenous communities and when it reinforces the
perception that humans must be separate from nature.
o
Habitat restoration
Habitat restoration repairs a natural area, damaged by destructive human
activities, back to its natural state. It is a promising mechanism to maintain
and restore biodiversity. A keystone species is a species that is critical in
maintaining the diversity within an ecosystem and their removal would
mean the collapse of the diversity of the ecological community. Evidence
shows that restoring keystone species are effective in restoring biodiversity.
o
Zoos and captive breeding
Zoos have played a critical role in conservation efforts through education
and captive breeding programmes. Zoos continue to transform from
facilities that simply collect and exhibit biodiversity, to facilities that are
dedicated to conservation. Evidence suggests that captive breeding of
endangered species is ineffective when the species are released back into
the wild, and zoos are not equipped for the number of species at risk. The
education that zoos and conservation provide have a great potential
positive impact on people's attitudes and actions.
12
ACTIVITY 4.2: SOUTH AFRICA'S BIODIVERSITY HOTSPOTS
Instructions
• Use the following link to access a blog on South Africa's biodiversity hotspots:
https://botanicalsociety.org.za/a-megadiverse-country-introducing-southafricas-biodiversity-hotspots/.
• Read through the blog by Poulsen (2020) to learn about South Africa's
biodiversity hotspots and why the country is famous for its biodiversity. Follow
the hyperlinks on the blog to view the geographic location of these hotspots.
• Go to the Blog tool on the GGH1503 module site.
• Reply to the blog post entitled "Activity 4.2: South Africa's Biodiversity
Hotspots" by following the task outlined below.
Purpose
To enrich the knowledge you have acquired in this learning unit of biodiversity and
biodiversity hotspots by helping you explore Africa's rich biodiversity, through
presenting South Africa as a famous case study.
Task
In your blog post, share your answers to the following questions with fellow students:
1. What physical factors contribute to South Africa's species richness?
2. How many biodiversity hotspots are there worldwide, and how many of these
are found on the African continent?
3. List the three biodiversity hotspots in South Africa and their geographic
locations.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
4.5 CAPSTONE ACTIVITY
LEARNING UNIT 4: CAPSTONE ACTIVITY
Instructions
• Go to the Discussions tool on the GGH1503 module site.
• Go to the topic entitled Learning Unit 4: Capstone Activity.
• Reply by providing your response on the tasks detailed below.
Purpose
To provide you with the opportunity to enhance your understanding and practical
knowledge of the challenges facing South Africa's biodiversity (in this case, animal
species). It equips you to meet the second and third of the module's three main
learning outcomes (as listed in the module overview) by analysing the
consequences of human activities on the natural environment and effectively
formulating solutions.
Task instructions
For this activity, you must do a basic internet search to identify which species of
pangolin can be found in South Africa. Once you have identified this specific
pangolin species, explore the IUCN Red List of Threatened Species at
13
https://www.iucnredlist.org/. Use the search box to search for, and open, the Red
List page dedicated to information on the pangolin species found in South Africa.
Examine the various sections on this page and apply what you have learnt from this
learning unit, to respond to the tasks below.
Tasks
1. What is the common name of the pangolin species that can be found in South
Africa and what is its status (category/criteria) on the Red List?
2. What are the three terrestrial habitat types for this specific pangolin species?
3. List and summarise the five key threats identified for this specific pangolin
species.
4. Of the list of conservation actions still needed for this specific pangolin
species, which one would you motivate is the most important to put in place,
and why?
4.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
4.6.1 Which option best describes bacteria that feed upon decaying organic matter
in the soil?
A. Eukaryotic
B. Autotrophic
C. Fungi
D. Cyanobacteria
E. Heterotrophic
4.6.2 Summarise the mechanism of evolution called natural selection.
4.6.3 Explain why biodiversity is important to the survival and welfare of human
populations.
4.6.4 List and explain some of the core threats to biodiversity.
4.6.5 What is the term for events characterised by dramatic shifts and sudden
losses in biodiversity?
14
4.7 CONCLUSION
Upon completion of this learning unit, you should know that life on Earth (in other
words, biodiversity) exists at different levels of organisation and is measured in various
ways (the number of species and individuals, their genetic diversity, the diversity of
ecosystems, and so forth). You should know that although biodiversity critically
supports the welfare and survival of human populations, it faces several threats. Any
degradation or loss of biodiversity places the sustainability of Earth's natural capital
and the benefits we extract from it at extreme risk. There are certain efforts at different
scales dedicated to preserving this biodiversity. Consider why it is important for a
country like South Africa to actively protect its biodiversity, and what this would mean
to you. Now that you have reached the end of learning unit 4, you may proceed to
learning unit 5.
4.8 REFERENCES
Archer, E., Dziba, L.E., Mulongoy, K.J., Maoela, M.A., Walters, M., Biggs, R.,
Cormier-Salem, M-C., DeClerck, F., Diaw, M.C., Dunham, A.E., Failler, P., Gordon,
C., Harhash, K.A., Kasisi, R., Kizito, R., Nyingi, W.D., Oguge, N., Osman-Elasha, B.,
Stringer, L.C., Tito de Morais, L., Assogbadjo, A., Egoh, B.N., Halmy, M.W.,
Heubach, K., Mensah, A., Pereira, L. & Sitas, N. 2021. Biodiversity and ecosystem
services on the African continent – What is changing, and what are our options?
Environmental Development, 37(100558): 1-9.
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Makina, A. & Luthuli, A. 2014. Corporate South Africa and biodiversity in a green
economy. International Journal of African Renaissance Studies – Multi-, Inter- and
Transdisciplinary, 9(2): 197-212.
Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Siddig, A.A.H. 2019. Why is biodiversity data-deficiency an ongoing conservation
dilemma in Africa? Journal for Nature Conservation, 50(125719):1-3.
Smith, T., Beagley, L., Bull, J., Milner-Gulland, E.J., Smith, M., Vorhies, F. &
Addison, P.F.E. 2020. Biodiversity means business: Reframing global biodiversity
goals for the private sector. Conservation Letters, 13(1) 1-10.
Theis, T. & Tomkin, J. (Editors). 2018. Sustainability: A Comprehensive Foundation.
OpenStax CNX. Available at: https://legacy.cnx.org/content/col11325/latest/pdf.
15
GGH1503
Learning Unit 5
THE ECOLOGY OF BIOLOGICAL COMMUNITIES
Contents
5.1
INTRODUCTION .......................................................................................................... 1
5.2
AIM AND LEARNING OUTCOMES ............................................................................ 2
5.3
PRESCRIBED MATERIAL .......................................................................................... 3
5.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 4
5.4.1
What is population ecology? ............................................................................. 4
5.4.2
How do populations change over time and space? ........................................ 4
5.4.3
What limits the growth of populations? ........................................................... 8
5.4.4
How do species interact within a community? ................................................ 9
5.4.5
The characteristics of communities and how they change over time ......... 11
5.4.6
Earth's terrestrial biomes ................................................................................. 12
5.5
CAPSTONE ACTIVITY .............................................................................................. 17
5.6
SELF-TEST ................................................................................................................ 18
5.7
CONCLUSION ........................................................................................................... 19
5.8
REFERENCES ........................................................................................................... 19
LEARNING UNIT 5
THE ECOLOGY OF BIOLOGICAL COMMUNITIES
Authors: Leani de Vries and Peter Schmitz
Academic editor: Kristy Langerman
1
A bee pollinating a flower (Source: Creative Commons, US Geological Survey)
"Climate change is expected to drive changes in ecosystem structure and
functioning as well as geographical shifts of ecosystems and biomes ...
Such ecosystem changes will impact the potential for future land uses and the
livelihoods of people in Africa…"
(Martens et al., 2020:341)
5.1 INTRODUCTION
In the previous learning unit, you learned that life on Earth is diverse and organised.
The biosphere is hierarchically organised, starting from Earth's large realms to major
biomes, to a wealth of different ecosystem types (Keith et al., 2020). Ecosystems then
consist of communities where different populations are interconnected. This hierarchy
of life on Earth is not static. Each level is dynamic with many interactions, and changes
over time and space, and the different levels are interconnected. Within each
population, community and ecosystem, organisms interact with one another and with
their environment to exchange energy and matter, which is essential to sustaining life
(Miller & Spoolman, 2018).
1
All images used in this learning unit are from free, publicly accessible sources.
https://search.creativecommons.org/photos/fe5d27e4-3d3f-4b9b-8ab9-f0ecb22f6ce6 (US Geological Survey)
https://www.pexels.com/photo/elephants-on-brown-mountain-631317/ (Frans van Heerden)
https://www.pexels.com/photo/leafless-tree-on-brown-sand-4762919/ (Frank Odenthal)
1
In this learning unit, we take a closer look at biological communities and these
essential interactions. You will be introduced to the basics of population ecology to
understand populations and how their dynamics are studied, in other words, how and
why they change, and how scientists make sense of this. Understanding changes in
species' populations is key for adequate policies and conservation management,
especially since much of these changes in recent decades have been caused by
anthropogenic factors, such as a change in population abundances and geographic
distribution (Angert et al., 2013; Bowler et al., 2018).
Furthermore, to zoom out and frame the broader picture of life on Earth, you will be
introduced to how populations form communities, how communities change, and how
species interact and play specific roles within these communities. The image on the
first page shows a bee pollinating a flower. The knowledge you gain from this learning
unit will help you to identify the type of species interaction and the specific role played
by the bee in the image.
At a larger level, we will also look at Earth's major terrestrial biomes and how each is
characterised. Understanding Earth's biomes is another element to understanding the
sustainability of life on Earth and forms part of important scientific studies. This kind of
knowledge will be important for those of us living in Africa; for example, since changes
in Africa's biomes are not only projected for the future but have already been observed
(Martens et al., 2020). Lastly, the learning unit reflects on different map sources in
continuation of your introduction to maps and geographic tools.
5.2 AIM AND LEARNING OUTCOMES
This learning unit aims to introduce you to the ecology of biological communities
through the basics of population and community dynamics. The learning unit aims to
introduce you to the larger environments (biomes) in which these function. In addition,
you will be introduced to the sources of maps (used to create maps and where we
source maps from). Once you have completed this learning unit, you can use the
outcomes to assess the quality of your learning experience. Assess whether you meet
each aim and outcome with confidence. If not, you are advised to dedicate more time
to those you are still having trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:
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Define population ecology.
List the characteristics by which populations are defined.
Define demography.
Explain how populations may differ and change over time and space.
Discuss the methods and tools that population ecologists use to measure and
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represent population characteristics.
Analyse what limits the growth of populations.
Describe how species interact within a community.
Discuss how communities change over time in response to environmental
conditions.
Define a biome.
Explain the nature and locations of Earth's terrestrial biomes.
List the sources used to create maps.
List the sources from which maps can be obtained.
5.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from two prescribed
open-access books.
The following chapters and sub-chapters are important for study purposes:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
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Chapter 3: Ecosystems and the Biosphere
3.3: Terrestrial Biomes
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Chapter 4: Community & Population Ecology
4.1: Population Demographics & Dynamics
4.2: Population Growth and Regulation
4.4: Community Ecology
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.
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Chapter 2: Population Ecology and Human Demography
2.1: What is Population Ecology?
2.2: Population Growth Models
2.3: Factors that Limit Population Growth
2.4: Life Tables and Survivorship
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This table summarises the study material for this learning unit.
Relevant sections
5.4
Prescribed material
Fisher,
Zehnder et al.,
2018
2018
Chapters 3 & 4
Chapter 2
3.3, 4.1, 4.2 and 4.4
2.1, 2.2, 2.3 and 2.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 5.2 and will help you to find your way through the study material.
5.4.1 What is population ecology?
Study chapter 2.1 in Zehnder et al. (2018).
Summary
 Ecology (a sub-discipline of biology) studies
the interaction between organisms and their
environment (living and non-living). A
population is a group of individuals of the
same species living within a particular area.
 Population ecology is therefore the study of how individuals of the same species
interact with their environment and change over time.
 Populations can be characterised by their size (symbolised by the letter N) (total
number of individuals) and density (number of individuals per unit of area or
volume). Population size and density are the two main characteristics used to
describe a population.
 Other population characteristics include dispersion (the spacing of individuals
within an area), sex ratio (proportion of females to males), age structure
(number of individuals in different age groups) and growth (change in the size
of the population over time, either increase or decrease).
5.4.2 How do populations change over time and space?
Study chapters 4.1 and 4.2 in Fisher (2018) and chapters 2.2 and 2.4 in Zehnder
et al. (2018).
Summary
 Populations are dynamic and their size and composition change in response to
several factors such as the change in season, natural disasters and resource
competition between and within species.
 Populations change over time and space as individuals are added through birth
or immigration (arrive from an outside population) and others die or emigrate
(depart from a population).
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Throughout time, and in response to changing environmental conditions,
populations grow and decline and their age and gender compositions change.
CONSERVING RHINO POPULATIONS
Instructions
 Watch the following video:
https://www.youtube.com/watch?v=rUHxVvw2LLo (3:27 minutes)
Purpose
 The video "Black rhinos moved to new home by helicopter | WWF" presents
the WWF's Black Rhino Range Expansion Project in which 19 critically
endangered black rhinos were moved from the Eastern Cape to Limpopo to
boost their population growth and breeding. It reflects on the conservation of
rhinos through managing populations.
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Demography is the study of populations.
Populations differ. For example, some populations have many individuals that
are densely distributed while others are sparsely distributed. Other populations
may have a smaller number of individuals that may either be densely or
sparsely distributed.
Population size can affect adaptation potential given the amount of genetic
variation in the population while population density can affect population
interactions such as resource competition (like competition for food) or
individuals' ability to find a mate.
The size of a population is most accurately determined by counting all the
individuals within the area; however, for large areas, this is not logistically or
financially feasible.
Scientists usually sample a representative portion of each area to make
inferences about the population as a whole. The specific sample method is
determined by the characteristics of the organism.
A quadrat is used for immobile or very small and slow-moving organisms. A
square structure is placed at random locations on the ground and used to count
the number of individuals in its boundaries. A mark-and-recapture method is
used for smaller mobile organisms. Captured animals are marked and released
back into the environment, whereafter a new sample is later captured to
determine how many marked animals are in the new sample.
A species distribution pattern refers to the distribution of individuals within a
habitat at a particular point in time. It reflects on important aspects of the biology
of the species and provides more information about how individuals interact
than does population density. Individuals within a population may either display
random, clumped or uniform distribution patterns. For example, plants that have
wind-dispersed seeds that germinate wherever they fall in favourable
environments, display a random distribution pattern.
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Tools used by population ecologists include life tables and survivorships
curves. These help to study species and identify the most vulnerable stages of
organisms' lives, to develop measures to maintain populations.
Life tables provide important information about the life history of an organism
and the life expectancy of individuals at different ages. Life tables track
survivorship, which is the chance of an individual in a given population surviving
to various ages.
A survivorship curve is a graph of the number (proportion) of individuals
surviving at each age interval versus time, to compare the life histories of
different populations. Life tables are used to construct survivorship curves
(survivorship is plotted on the y-axis as a function of age or time on the x-axis).
There are three types of survivorship curves.
In a type I curve, mortality is low in the early and middle years and occurs mostly
in older individuals (organisms have the highest probability of surviving every
age interval until old age when the risk of dying increases dramatically). In a
type II curve, mortality is relatively constant throughout the life span (species
have an equal chance of dying at any age). In a type III curve, early ages
experience the highest mortality while the lowest mortality is experienced by
older individuals (juvenile survivorship is very low and many individuals die
young). Examples include humans and most large mammals (type I curve),
birds (type II curve) and trees (type III curve).
Most species do not have survivorship curves that are definitively type I, II or III
and can range between the types. These three types represent the extremes
and help population ecologists to make predictions.
Population dynamics, such as population growth, are modelled using several
methods. An accurate model should describe population changes (such as
size) and predict future changes over time and under different conditions.
The two simplest models of population growth use deterministic equations (do
not account for random events) to determine the rate of change in population
size over time. These models do not adequately model natural populations;
however, they do provide points of comparison.
Firstly, exponential growth (yields a J-shaped curve) describes populations that
increase in numbers without any limits to their growth. Exponential growth
means a population is increasing by a fixed percentage each year with an
accelerating pattern of increasing population size. However, extended
exponential growth is only possible with infinite resources and no external limits
(such as food), which is not the case in the natural world.
Secondly, logistic growth (yields an S-shaped curve) occurs because of limits
to reproductive growth as the population size increases. Most natural
populations exhibit logistic growth. At first, the population grows nearly
exponentially when the population is very small and there are plentiful
resources. When the number of individuals gets large enough, resources are
depleted, and the growth rate slows and eventually levels off (plateau) with a
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zero-population growth rate. The maximum population size that a particular
environment can sustain is called the carrying capacity (symbolised by the letter
K). In real populations, a growing population often overshoots its carrying
capacity and the death rate increases beyond the birth rate, causing a
population size decline back to the carrying capacity or below. As more
resources become available, the population grows again. Fluctuations in
population size continue to occur as the population cycles around it carrying
capacity (exhibiting a logistical model).
Population ecologists have hypothesised that certain characteristics (lifehistory characteristics such as birth rates, number of offspring, and so forth)
may evolve in species that lead to adaptations to their environment. These
adaptations then impact the kind of population growth experienced by the
environment's species.
Species vary in their reproductive patterns. Population ecologists have
described a continuum of life history "strategies" where K-selected species are
on the one end and r-selected species are on the other.
K-selected species are adapted to stable and predictable environments; tend
to exist close to their carrying capacity; tend to have larger but fewer offspring;
contribute many resources and much parental care to each offspring. r-selected
species are adapted to unstable and unpredictable environments; have large
numbers of small offspring; and do not allocate many resources or parental
care to each offspring that are relatively self-sufficient at birth.
EXTRACT FROM THE EXPERTS
Demography in Action:
Aloidendron dichotomum (quiver tree) populations at the Square
Kilometre Array (SKA)
Helga van der Merwe, Arid Systems Ecologist, South African
Environmental Observation Network (SAEON): Arid Lands Node,
writes:
The iconic succulent quiver tree, Aloidendron dichotomum, is
found throughout the arid and semi-arid regions of South Africa
and Namibia. It has a long lifespan and is structurally
heterogeneous across its distribution range. In order to shed
some light on the demography of the species at the Square
Kilometre Array (SKA) field surveys were conducted at four sites.
These data were analysed by means of size class distribution
(SCD) curves.
Our study found that when plotting basal diameter classes, a
Type I SCD curve (following an inverse J-shaped curve) was
constructed for two SKA populations representing the ideal curve
shape for a species in a natural environment. This curve shape
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displays a constant decrease in the number of individuals as the
size classes increase, and spans the whole range of size classes
described for the species. Type II curves were found for the
remaining two SKA populations with a near ideal population
structure that differs from a Type I curve only by having a lower
abundance of smaller size classes. Past these smallest size
classes, the size class distribution resumes a typical Type I
inverse J-shape.
At present, the A. dichotomum populations surveyed at four sites
at SKA appear to be in good health and are recruiting. This study
highlights that the choice of population surveyed is of crucial
importance and that a wide range of populations in close
proximity to one another and at different sites situated across
their distribution range have to be surveyed in order to produce
an unbiased assessment of A. dichotomum populations.
5.4.3 What limits the growth of populations?
Study chapter 2.3 in Zehnder et al. (2018).
Summary
 Eventually, as populations grow, one or more environmental factors will limit
the population growth rate as the population size approaches the carrying
capacity and density increases.
 Density-dependent factors are the environmental variables that depend on the
density of a population while factors that are not related to the density of a
population are called density-independent factors.
 Most density-dependent factors are biological (biotic) and may include
predation, inter- and intraspecific competition for resources, waste
accumulation and diseases. Usually, higher population density results in higher
death rates and lower birth rates.
 Density-independent birth rates and death rates do not depend on population
size and are independent of population density. Density-independent factors
include, for example, weather extremes, natural disasters and some other
physical or abiotic factors.
ACTIVITY 5.1: EXPLORING POPULATION GROWTH
RESEARCH IN SOUTH AFRICA
Instructions
 Use the following link and download the research article on elephant
population growth in the Kruger National Park:
https://koedoe.co.za/index.php/koedoe/article/view/1427/2067.
 Read through the article by Ferreira, Greaver and Simms (2017) to learn how
they researched the change in the elephant population of the Kruger National
Park, following the change in philosophy by the Kruger National Park to
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manage landscapes as opposed to managing elephants. In doing so,
consider the knowledge you have gained from the preceding section.
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 5.1: Exploring Population Growth
Research in South Africa" by following the task outlined below.
Purpose
To expose you to the platform of academic research and the value of academic
literature in advancing science. This South African research will help you to
understand the relevance of population ecology in better understanding the ecology
of our biological communities. This will help you to apply some of the knowledge you
have acquired when reading and processing academic research.
Task
In your blog post, share your answers to the following questions with fellow students:
1. What method was used in 2015 to determine the elephant population in the
Kruger National Park and what was the determined population size (N)?
2. From Figure 1 in the article, was population density generally highest around
the periphery or the centre of the Kruger National Park?
3. What was the annual population growth rate during the intensive elephant
management era (which ended in 1994)?
4. How did the annual population growth over the last generation of elephants
(the 12 years from 2003 to 2015) compare to the abovementioned rate?
5. How did the change in philosophy pre- and post-2015 determine this change
in the annual population growth of the elephant populations?
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
5.4.4 How do species interact within a community?
Study chapter 4.4 in Fisher (2018).
Summary
 Populations typically do not live in isolation from other species and interact
within a given habitat to form a community.
 The diversity of a community relates to the number of species occupying the
same habitat and their relative abundance.
 Scientists study ecology at the community level to understand how species
interact with each other and compete for the same resources.
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The predator-prey relationship is a classic example of species interactions.
Predation is when the individuals of one population kill and consume the
individuals of another population.
Natural selection strongly influences predation and predator avoidance.
Heritable characteristics (traits) that allow an individual of a prey population to
better evade its predators, and likewise, that allow an individual of a predator
population to better locate and capture its prey, will lead to a greater number of
offspring in that population and the commonness of that trait within the
population in later generations.
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Species have evolved numerous mechanisms to escape predation and
defences may be mechanical, chemical, physical or behavioural. Examples
include body shape and colouration to avoid being detected by predators. Some
predators then learn to avoid capturing and eating certain potential prey based
on these defence characteristics like colouration. Other species employ
mimicry and adopt the defence or warning symbol of the prey species to avoid
being captured and eaten (even if they are harmless).
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Resources are often limited within a habitat and species must compete for
them.
All species have an ecological niche that is the unique set of resources used
by a species, including its interaction with other species.
According to the competition exclusion principle, two species cannot occupy
the exact same niche in a habitat. Competition is disadvantageous for both
competitors as it wastes energy. If there is competition between two species for
the same resources, natural selection will favour traits that lessen the reliance
on the shared resource and subsequently reduce competition. If either is unable
to evolve to reduce competition, the species that exploits the resource most
efficiently will drive the extinction of the other species.
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Symbiosis refers to the close, long-term, interactions between individuals of
different species. Symbiosis may be commensal, mutualistic or parasitic.
Commensalism occurs when one species benefits from an interaction, while
the other species is neither harmed nor benefits.
Mutualism occurs when two species benefit from their interaction.
Parasitism occurs when the parasitic organism (parasite) lives in or on (for
example, feeds off) another organism (the host), weakening but rarely killing it.
The parasite benefits while the host is harmed. Parasitism can be considered
a form of predation.
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ACTIVITY 5.2: SPECIES INTERACTIONS
Task
Look at the image below of a red-billed oxpecker feeding on the ticks on the impala
and identify which species interaction is displayed here.
Red-billed oxpecker and impala (Source: Creative Commons, Bernard Dupont)
Purpose
To assist you in identifying and expanding your practical knowledge on the different
types of species interactions.
5.4.5 The characteristics of communities and how they change over time
Study chapter 4.4 in Fisher (2018).
Summary
 Communities are complex and are characterised by their structure (population
size and interactions) and dynamics (how the population size and interactions
change over time).
 A fundamental characteristic of communities is biodiversity, and a measure of
this biodiversity is the number and relative abundance of different species in a
particular area.
 Species richness describes the number of species living in a particular area, it
varies across the globe and is related to latitude (greater near the equator and
lower near the poles), amongst other factors.
 Relative abundance is the number of individuals in a species relative to the total
number of individuals in all species within a system.
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Foundation species are considered the 'base' or 'bedrock' of a community and
have the greatest influence on its overall structure (often have the highest
relative abundance).
Keystone species have a key effect in maintaining the prevalence of various
species in an ecosystem. They play a critical role in helping to sustain
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ecosystems. The absence of a keystone species reduces biodiversity and alters
species composition.
Invasive species (non-native organisms) alter the community they invade when
introduced to an area outside of their native range. These species compete with
native species for their resources and alter habitats and environments.
Community dynamics refer to the changes in the structure and composition of
communities over time. These often follow environmental disturbances such as
earthquakes or fires.
Communities with a relatively constant number of species are said to be at
equilibrium (equilibrium is dynamic but maintains a relatively constant number).
Following a disturbance, communities may or may not return to equilibrium.
Succession refers to the sequential change (appearance and disappearance)
of species in a community over time following a disturbance.
In primary succession, a newly formed or exposed area is colonised by living
organisms while in secondary succession, a part of an ecosystem is disturbed,
and remnants of the previous community remain.
An example of primary succession is bare rock exposed by a retreating glacier.
The bare rock is devoid of life, but new soil is slowly formed and leads to the
establishment of organisms such as lichens. Pioneer species are the first
species to occur from primary succession.
An example of secondary succession is a forest cleared by wildfire or logging.
While most forest organisms are destroyed or flee, the nutrients are returned to
the ground in the form of ash. The soil is then provided with a foundation for
rapid recolonisation. Intermediate species develop from this, and after time,
when the forest reaches its equilibrium and resembles the community before
the disturbance, this equilibrium state is called the climax community. Climax
communities are typically characteristic of a given climate and geology.
5.4.6 Earth's terrestrial biomes
Study Chapter 3.3 in Fisher (2018).
Summary
 Biomes are large-scale environments
distinguished
by
characteristic
temperature ranges and precipitation.
These determine the types of fauna and
flora that exist in those areas. The same
biomes, sharing similar climates, can occur in geographically distinct areas.
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The eight major terrestrial biomes are tropical rainforests, savannas,
subtropical deserts, chaparral, temperate grasslands, temperate forests, boreal
forests and arctic tundra.
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Tropical rainforests are found in equatorial regions and are the most
biodiverse terrestrial biome with high net primary productivity. The vertical
layering of vegetation forms distinct habitats for animals within each layer.
They have average temperatures of 20 °C to 34 °C and annual rainfall
ranges from 125 cm to 660 cm with considerable seasonal variation.
Savannas are grasslands with scattered trees found in Africa, South
America and Northern Australia. They are hot, tropical areas with
temperatures averaging from 24 °C to 29 °C and an annual rainfall of 51 cm
to 127 cm. They have an extensive dry season and consequent fires.
Subtropical deserts are centred around the Tropic of Cancer and Tropic of
Capricorn with relatively little biodiversity. They are typically located on the
downward (lee side) of mountain ranges, which create a rain shadow after
prevailing winds drop their water on the mountains, creating arid and
semiarid conditions. Hot deserts have low annual precipitation of less than
30 cm and high variation in daytime and night-time temperatures. Cold
deserts experience freezing temperatures during the winter and
precipitation in the form of snowfall.
Chapparal (scrub forest) is found along southern California, the
Mediterranean Sea, southwestern South Africa and along the southern
coast of Australia. Annual rainfall is between 65 cm and 75 cm and occurs
mostly in the winter. The vegetation is dominated by shrubs that are
adapted to periodic fires.
Temperate grasslands are found through central North America and
Eurasia. They have pronounced annual fluctuations in temperature with hot
summers and cold winters. Annual precipitation ranges from 25.4 cm to
88.9 cm. Grasses are the dominant vegetation with few trees and there are
frequent fires.
Temperate forests are found in the midlatitudes in eastern North America,
Western Europe, Eastern Asia, Chile and New Zealand. Temperatures
range between -30 °C to 30 °C with relatively constant precipitation
throughout the year, ranging between 75 cm and 150 cm. The dominant
vegetation is deciduous trees with fewer evergreen conifers. The tree
species diversity is much less than tropical rainforests.
Boreal forests, also called taiga or coniferous forests, are found between
50° and 60° north latitude across most of Canada, Alaska, Russia and
northern Europe. They have cold, dry winters and short, cool and wet
summers. Annual precipitation is from 40 cm to 100 cm. This has led to the
predominance of cold-tolerant, cone-bearing plants (evergreen coniferous
trees). The net primary productivity and species diversity are less than that
of tropical and temperate forests.
Arctic tundra is found throughout the Arctic regions of the Northern
Hemisphere. The average winter temperature is -34 °C and the average
summer temperatures are between 3 °C and 12 °C, while the annual
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precipitation is low (15 cm to 25 cm) with little annual variation. There is
little species diversity and low net primary productivity.
INTRODUCING GEOGRAPHIC TOOLS AND MAPS
Map sources
In this section, we will look both at sources that are used to create maps and where
we source maps from. First, we will list a few sources for creating maps and second,
we will explore sources from where maps can be obtained.
Sources used in maps
 Direct observations are made by a person such as a surveyor. The surveyor
then translates the surveyed data into a map. The surveyor obtains the data
using various instruments such as a theodolite (image below) and differential
GPS systems and resources such as benchmarks, town survey marks,
trigonometric beacons and continuously operating GNSS network data. The
National Geo-Spatial Information (NGI) provides these resources to
surveyors operating in South Africa (http://www.ngi.gov.za/index.php/whatwe-do/geodetic-and-control-survey-services). The maps that are created by
surveyors are known as cadastral maps that shows detailed information
properties that are either privately or publicly owned.
Surveyor doing his job. (Source:
https://www.canyons.edu/_resources/images/academics/schools/careereducation/index01
.jpg)
The image below shows the resultant survey (cadastral) map showing property
boundaries and servitudes. Servitudes are specific land parcels used for roads,
sewage systems and other infrastructures such as fibre, stormwater reticulation and
potable water networks.
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Survey map showing cadastral boundaries (Source: Prof Peter Schmitz, Unisa)
Other sources of data and information used to create maps are:
 Maps such as topographic maps that are used to map flood lines based on
contours and political maps showing municipal boundaries are used to create
census data maps.
 Aerial photographs from which spatial entities are identified and used to
create maps. A common example is the use of aerial photographs to
determine road networks and topographic features that are used to create
topographic maps and orthophotos (image on the next page). The modern
version of aerial photography is digital aerial imagery at very fine resolutions.
Visit http://www.ngi.gov.za/index.php/what-we-do/aerial-photography-andimagery/35-colour-digital-aerial-imagery-at-0-5m-gsd-2008-2016-and-025m-gsd-2017-current for examples of digital aerial imagery.
 Satellite imagery is digital imagery captured by satellites. They have various
resolutions depending on the purpose of the satellite. Geostationary weather
satellite imagery has a low resolution of 3 km for the second-generation
Eumetsat to Pleiades Neo imagery at 30 cm. Military-specification satellites
have even finer resolutions. Visit https://en.sat24.com/en/za to view live
weather satellite imagery of South Africa. Satellite imagery is used to
generate, for example, land cover and land use maps.
Visit https://egis.environment.gov.za/sa_national_land_cover_datasets for a
description of South African land cover datasets.
 Spatial data such as the various spatial data sets from Statistics South Africa
ranging from small area layers to sub-places to voting districts, wards,
municipalities, district municipalities to provinces and South Africa for the
display of census data at various levels of resolutions. Other spatial data
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include road and rail networks, airports, rivers, lakes and dams, topographic
maps and digital elevation models, to name a few.
Data such as non-spatial data can be linked to spatial data such as census
data, crime data, food security data and household survey data.
VGI is the acronym for Volunteered Geographic Information that is collected
by volunteers to assist in special projects such as bird atlases or assisting in
humanitarian operations such as earthquakes, floods, wildfires, and so forth.
The most well-known VGI operation was the Ushahidi project from the 12
January
2010
Haiti
earthquake.
Visit
https://www.ushahidi.com/blog/2012/01/12/haiti-and-the-power-ofcrowdsourcing for more information.
Orthophotograph (Source:
http://www.ngi.gov.za/images/stories/products/maps/large/2931CC_06_1_10-000Orthophoto_ED5.jpg)
Sources of maps
There are several sources from which maps can be obtained in various digital
formats. Some also offer printed maps. A few of these sources include:
 Government organisations such as NGI (http://www.ngi.gov.za),
Department of Fisheries, Forestry and Environment (DFFE)
(https://egis.environment.gov.za), United States Geological Survey (USGS)
(https://www.usgs.gov), Ordnance Survey of the United Kingdom
(https://www.ordnancesurvey.co.uk), Council for Geoscience (CGS)
(https://www.geoscience.org.za), and Municipal Demarcation Board (MDB)
https://www.demarcation.org.za) to name a few.
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



International organisations such as the Food and Agriculture Organisation
of the United Nations (FAO) (http://www.fao.org/home/en/)
Internet Apps such as Google Maps and Google Earth
Volunteered maps such as Open Street Maps
(https://www.openstreetmap.org/)
Data resellers and companies such as AfriGIS (https://www.afrigis.co.za)
and GeoTerraImage (https://geoterraimage.com)
Other possible sources include other state departments, municipalities,
universities and organisations such as the World Bank
(https://www.worldbank.org/en/home) and Statistics South Africa
(http://www.statssa.gov.za).
5.5 CAPSTONE ACTIVITY
LEARNING UNIT 5: CAPSTONE ACTIVITY
Instructions
 Go to the Discussions tool on the GGH1503 module site.
 Go to the topic entitled Learning Unit 5: Capstone Activity.
 Reply by providing your response on the tasks detailed below.
World map of average annual precipitation in 2014 (Source: World Bank)
17
Purpose
To apply the knowledge you have acquired in this learning unit regarding biomes
and the reading, interpreting and sourcing of maps. It equips you to meet the first of
the module's three main learning outcomes (as listed in the module overview) by
providing you with the opportunity to explore the complexities of the natural
environment and doing so by using geographical tools.
Task instructions
For this activity, you will need to analyse the map provided above (which illustrates
average annual precipitation in 2014, across the regions of the world).
The map is available at: https://ourworldindata.org/grapher/average-precipitationper-year.
You then need to search for a reliable map that displays Earth's terrestrial biomes
and analyse their geographic locations (such as a digital map sourced from the
internet or a printed map acquired from a library collection or a book).
Place the maps side by side and respond to the tasks below.
Task
1. Explain why the two maps you have placed side by side share striking
similarities.
2. List the biome type(s) that are geographically located on the equator.
3. Briefly consider how the geographic location of the biome(s) (on the equator)
influences the typical precipitation characteristics and, in turn, briefly discuss
how this determines the type of flora and fauna that are typically found there.
5.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
5.6.1 List and define the two main characteristics used to describe a population.
5.6.2 Explain whether exponential growth (J-shaped curves) adequately model
population growth in real populations.
5.6.3 Describe the defence mechanism employed by the monarch butterfly to evade
its predators.
5.6.4 Honeybees pollinate flowering species, without which ecosystems would be
dramatically different or cease to exist. Of what type of species is this an
example?
18
5.6.5 Which statement about the three major forest biomes is false?
A. Tropical rainforests are found in equatorial regions.
B. Temperate forests have the highest species diversity and the lowest net
primary productivity.
C. The trees in temperate forests do not grow as tall as the trees in tropical
rainforests.
D. Boreal forests have cold, dry winters and short, cool and wet summers.
5.7 CONCLUSION
Upon completion of this learning unit, you should know the basics of the ecology of
biological communities. You should understand that populations are dynamic in the
way they change over time and space and respond to different environmental
conditions. You should know more about population ecology and how populations are
studied. This learning unit exposed you to the organisation of ecosystems at different
levels. Not only did you learn about population ecology, but also how different
populations interact to form communities and how species interact with each other. At
a larger level, you were introduced to Earth's major terrestrial biomes and what
characterises each. Do you recognise the biome in which you live? Now that you have
reached the end of learning unit 5, you may proceed to learning unit 6.
5.8 REFERENCES
Angert, A.L., LaDeau, S.L. & Ostfeld, R.S. 2013. Climate change and species
interactions: ways forward. Annals of the New York Academy of Sciences, 1297:1-7.
Bowler, D.E., Heldbjerg, H., Fox, A.D., O'Hara, R.B. & Böhning-Gaese, K. 2018.
Disentangling the effects of multiple environmental drivers on population changes
within communities. Journal of Animal Ecology, 87:1034-1045.
Ferreira, S.M., Greaver, C. & Simms, C. 2017. Elephant population growth in Kruger
National Park, South Africa, under a landscape management approach. Koedoe,
59(1), a1427. Available at http://dx.doi.org/10.4102/koedoe.v59i1.1427.
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Keith, D.A., Ferrer, J.R., Nicholson, E., Bishop, M.J., Polidoro, B.A., Ramirez-Llodra,
E., Tozer, M.G., Nel, J.L., MacNally, R., Gregr, E.J., Watermeyer, K.E., Essl, F.,
Faber-Langendoen, D., Franklin, J., Lehmann, C.E.R., Etter, A., Roux, D.J., Stark,
J.S., Rowland, J.A., Brummitt, N.A., Fernandez-Arcaya, U.C., Suthers, I.M., Wiser,
S.K., Donohue, I., Jackson, L.J., Pennington, R.T., Pettorelli, N., Andrade, A.,
19
Kontula, T., Lindgaard, A., Tahvanainan, T., Terauds, A., Venter, O., Watson, J.E.M.,
Chadwick, M.A., Murray, N.J., Moat, J., Pliscoff, P., Zager, I. & Kingsford, R.T. 2020.
The IUCN Global Ecosystem Typology v1.01: Descriptive profiles for Biomes and
Ecosystem Functional Groups. Available at:
https://iucnrle.org/static/media/uploads/references/researchdevelopment/keith_etal_iucnglobalecosystemtypology_v1.01.pdf.
Martens, C., Hickler, T., Dacis-Reddy, C., Engelbrecht, F., Higgins, S.I., von Maltitz,
G.P., Midgley, G.F., Pfeiffer, M. & Scheiter, S. 2021. Large uncertainties in future
biome changes in Africa call for flexible climate adaptation strategies. Global Change
Biology, 27:340-358.
Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
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GGH1503
Learning Unit 6
HUMANKIND: POPULATION AND DYNAMICS
Contents
6.1
INTRODUCTION ........................................................................................................ 1
6.2
AIM AND LEARNING OUTCOMES ........................................................................... 3
6.3
PRESCRIBED MATERIAL......................................................................................... 4
6.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 5
6.4.1
How do human population dynamics work? ................................................... 5
6.4.2
What is demography? ....................................................................................... 7
6.4.3
How do environmental conditions impact the human population? ............. 10
6.4.4
What is environmental health? ....................................................................... 11
6.4.5
What is environmental toxicology? ............................................................... 12
6.5
CAPSTONE ACTIVITY ............................................................................................ 14
6.6
SELF-TEST .............................................................................................................. 15
6.7
CONCLUSION ......................................................................................................... 16
6.8
REFERENCES ......................................................................................................... 16
LEARNING UNIT 6
HUMANKIND: POPULATION AND DYNAMICS
Author: Leani de Vries
Co-authors: Chris Vlok and Peter Schmitz
Academic editor: Kristy Langerman
1
People in a street in Mukono, Uganda (Source: Unsplash.com, Antoine Plüss)
"One needs only to peruse the daily news to be aware that humanity is on a
dangerous and challenging trajectory."
"In relatively recent times, human life evolved, and in large part due to our
extraordinary intelligence, has become the dominant life form on the planet."
(Lidicker, 2020:1)
6.1
INTRODUCTION
You now know more about how natural ecosystems function and how energy flows
within them from when primary producers first convert solar energy into food to when
species feed on others for food. You also know more about the importance of
biodiversity and our biological communities. Humans are tertiary consumers that feed
at the highest trophic level where the least usable energy is available. This alone
1
All images used in this learning unit are from free, publicly accessible sources.
https://unsplash.com/photos/MsKv6HCQ0F0 (Antoine Plüss)
https://search.creativecommons.org/photos/f9d36474-01b0-400c-a0f9-1eaf7e5e3ddd (perpetualplum)
https://unsplash.com/photos/X_tEarX6svc (Gallery DS)
1
indicates a certain vulnerability inherent to the species. In natural ecosystems, the
species that feed at the higher trophic levels have smaller population numbers than
those that feed lower down in the food chain. To be sustainable, a natural ecosystem
must have more primary producers than primary consumers, more primary consumers
than secondary consumers, and so on. When the numbers of higher-level feeders
increase beyond that which can be sustained, the carrying capacity of the system has
been exceeded and the system has become unsustainable.
Humankind is the dominant species on Earth and its population is growing
significantly. The world population stands at around eight billion and projections
estimate that we will reach 10 billion by 2050 (Lidicker, 2020). The rapid growth of the
human population and our impact on Earth's natural capital brings about the question
of how long it can keep growing (Miller & Spoolman, 2018). In other words, when will
we reach carrying capacity? This is not a straightforward question and there is no
simple answer. It is difficult for scientists to project human population growth and put
a fixed number to its limit (Henderson & Loreau, 2018). It is important to recognise that
'solving' population growth is not the only answer to reducing our impact on Earth. We
are also excessively consuming Earth's natural resources and services, which must
be addressed by both more developed and less developed countries alike. Clearly, we
cannot survive alone, and our success depends on the proper functioning of Earth's
natural capital (Ganivet, 2020; Lidicker, 2020).
As individuals, we each lead a life where we depend on and leave a footprint on our
human and natural environments and the resources and services they offer. The
image of a street in Mukono, Uganda, is a snapshot of this everyday life and
interaction. When we use transport to go to work or school, or when we buy vegetables
or clothes from a local market, we are role players in the functioning of our living Earth.
In this learning unit, you will gain an understanding of the human population through
an introduction to the basics of demography, in other words, the study of the size of
human populations and other related dynamics. You will also learn more about the
interplay between the health of the environment and the human population.
2
ACTIVITY 6.1: THE WORLD IN NUMBERS
Instructions
• Use the following link to explore the current world population
https://www.worldometers.info/world-population/.
• Follow the changing figures on the Worldometer website about the number
of births and deaths and growth rates.
• Feel free to explore the various other world population sections on the
website, such as population by country.
• Go to the Blog tool on the GGH1503 module site.
• Reply to the blog post entitled "Activity 6.1: The World in Numbers" by
following the task outlined below.
Purpose
To expose you to the significant growing trends of the world's population. This will
help you to put the importance of a sustainable human society into perspective and
understand what Lidicker (2020) calls a dangerous and challenging trajectory.
Task
In your blog post, share with fellow students:
1. the three countries with the highest populations on the day you visited the
website,
2. a reflection on whether you think the top three rankings will change in the
near future, and
3. your thoughts on how South Africa's population is growing.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
6.2 AIM AND LEARNING OUTCOMES
This learning unit aims to teach you the basics of demography and the complex
interrelationship between the health of the human population and the health of the
environment to understand humans as the ultimate consumers on Earth. Once you
have completed this learning unit, you can use the outcomes to assess the quality of
your learning experience. Assess whether you meet each aim and outcome with
confidence. If not, you are advised to dedicate more time to those you are still having
trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:
•
•
•
•
Briefly explain the history of human population dynamics.
Define demography and discuss the factors that influence the size and growth
of the human population.
Understand the tools that demographers use to study and predict future
populations trends.
Analyse how a population's age structure can affect its growth or decline.
3
•
•
•
•
Understand the demographic transition model.
Discuss the interdependence of environmental health and the health of human
populations.
Consider environmental toxicology as a field in which this human-environment
interdependence is pronounced.
Define GIS.
6.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from two prescribed
open-access books.
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
•
o
Chapter 4: Community & Population Ecology
4.3: The Human Population
•
o
o
o
Chapter 6: Environmental Hazards & Human Health
6.1: The Impacts of Environmental Conditions
6.2: Environmental Health
6.3: Environmental Toxicology
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.
•
o
o
Chapter 2: Population Ecology and Human Demography
2.5: The Human Population
2.6: Demography
This table summarises the study material for this learning unit.
Prescribed material
Fisher,
Zehnder et al.,
2018
2018
Chapters 4 & 6
Chapter 2
Relevant sections
4.3, 6.1, 6.2 and 6.3
4
2.5 and 2.6
6.4 KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 6.2 and will help you to find your way through the study material.
6.4.1 How do human population dynamics work?
Study chapter 4.3 in Fisher (2018) and chapter 2.5 in Zehnder et al. (2018).
Summary
• The same concepts of animal population dynamics can be applied to human
population growth. Humans, however, can alter their environment to increase
carrying capacity, sometimes leading to the detriment of other species. The
human population and use of resources are growing to such an extent that there
is concern about the ability of Earth's environment to sustain its human
population. Potential risks of large-scale exponential growth include, for
example, famine and disease.
• Firstly, during early human history, the human population was held in check by
diseases, famines and wars. Secondly, at the start of the Agricultural Revolution
(10 000 BC), there were only five to ten million people on Earth. Human
societies transitioned from small nomadic hunter-gatherers to larger stationary
farming societies that lead to a dramatic human population increase (increased
food supply, more children to assist with farm labour, lower death rates).
Thirdly, at the start of the Industrial Revolution (in the 1700s), there were around
one billion people on Earth. The revolution involved progress in agricultural
production, engineering, commerce, information technology, sanitation and
health care, which led to an even lower death rate and the next wave of
increased population growth.
• The fundamental cause of accelerated population growth over the past 200
years has been reduced death rates from changes in public health and
sanitation (clean drinking water, proper sewage disposal and medical
innovations). The historical human population growth pattern demonstrates its
capacity to exhibit exponential growth.
• It is estimated that the current consumption levels combined with the size of the
population are far beyond Earth's carrying capacity.
• Before scientific and technological advances, theories about population growth
included that of Thomas Malthus (1766-1834) and Karl Marx (1818-1883).
Malthus suggested that populations tended to increase at an exponential rate
while food production remained stable or increased slowly, predicting that
human populations would eventually outstrip food supply leading to starvation,
crimes and misery. Marx, on the other hand, viewed poverty, resource
depletion, pollution and other social ills as the cause of population growth and
argued that stopping this growth required the elimination of these social ills.
5
•
•
In reality, food supplies increased faster than population growth since Malthus'
time. Agricultural productivity, engineering, information technology, commerce,
medicine, sanitation and other modern achievements have made it possible to
support thousands of times as many people per unit area as was possible
10 000 years ago. However, this has caused an unprecedented alteration to
the environment and ecosystems to the point where some are in danger of
collapse. It is likely that the negative effects will outweigh the positive ones and
that the world's carrying capacity might decrease.
Many dire predictions have been made about the world population leading to a
major crisis called the population explosion, such as in biologist Paul R.
Ehrlich's 1968 book The Population Bomb. While these predictions did not bear
fruit, the laws of exponential population growth are still in effect in certain parts
of the world, and unchecked population growth cannot continue indefinitely.
Examples of attempts to curb the crisis include population control policies.
EXTRACT FROM THE EXPERTS
Kate Joseph, Deputy Director: Strategy and Research, from the City of
Johannesburg, writes:
Johannesburg is a young city. The settlement sprang up in 1886
when prospectors found gold, and quickly transformed into the
biggest city in South Africa and the economic hub of Gauteng
and the country. Today, the city continues to attract people
looking for economic opportunities. Over the last decade the
average population growth rate for Johannesburg (2.79%) was
nearly double the growth rate of South Africa as a whole (1.59%).
The city's population grew from 4.4 million people in 2011 to an
estimated 5.8 million in 2020. Stats SA projects that the
population will reach 7.5 million by 2030. The bulk of the current
population is young, working-age people; just over half of whom
were born in the Gauteng province (56%). The rest migrated into
the city from other parts of South Africa (33%) and some from
other countries (10%).
Like many large cities around the world, Johannesburg faces
typical developmental challenges such as climate change,
economic downturn, poverty and inequality, and housing and
infrastructure backlogs. The above trends are exacerbated by
rapid urbanisation – A population growing quickly is difficult to
plan for and frequently leads to sprawling (often informal)
developments, urgent new service demands, competition, and
added pressure on existing, aging infrastructure. Conversely,
being overly prepared is not necessarily the solution for town
planners either: in China, whole cities were built; but no-one ever
moved in.
6
Beginning in the early 2000s the City of Johannesburg – like
other global cities – embraced long-term planning as part of its
strategic response to such challenges. Long-term plans better
enable government to attend to challenges that require extensive
lead times and allow for agile responses to current, complex
uncertainties while still maintaining clear goals. The City's current
long-term plan is The Joburg 2040 Growth and Development
Strategy (GDS). This is an aspirational strategy that defines the
type of society we want to achieve by the year 2040; by analysing
where we are now as a City (and where we come from) and
identifying intervention areas that we need to focus on in order to
achieve our desired outcomes. The City's development paradigm
identifies four key, inter-related drivers, namely: 1) human and
social development; 2) inclusive and productive economic
growth; 3) environment and services (including the related
infrastructure); and 4) governance. Taken together these support
the achievement of resilience, sustainability and liveability. This
requires a whole-of-society approach. The GDS invites all
stakeholders – be they temporary or permanent, visitors or
citizens – to join the City of Johannesburg as part of a collective
team to realise a resilient, sustainable and liveable city for all.
6.4.2 What is demography?
Study chapter 4.3 in Fisher (2018) and chapter 2.6 in Zehnder et al. (2018).
Summary
• Demography applies the principles of
population ecology to the human population.
Demographers study and compare human
population growth, decline and change in
terms of age and gender compositions using
statistics such as births, deaths, population
size and where people live.
• Demographically, there are two disparate worlds. The industrialised or
developed world includes European nations, the United States, Canada, Japan,
Australia, and so forth. Its population can be generalised as old, rich and stable.
Less-industrialised, less-developed or developing nations, on the other hand,
have populations that are generally young, poor and rapidly growing (these
include Asia, Africa and Latin America). Countries such as China, India, Brazil,
Mexico, South Africa and Russia fall between these two extremes and are
sometimes referred to as newly industrialised or emerging market economies.
• Demographers use the age structure diagram to understand and predict
populations trends. The age structure is the proportion of a population in
different age classes. The age structure diagram shows the distribution by ages
of females and males within a certain population.
7
•
•
•
•
•
•
•
•
Age classes between 0 and 15 years are pre-reproductive, between 15 and 45
years are reproductive, and above 45 years are post-reproductive.
Countries with rapid growth have a pyramidal shape in their age structure
diagrams, showing a prevalence of younger individuals (many of reproductive
age). This is most often observed in less-developed countries with a high birth
rate and a low life expectancy. Age structures of areas with slow growth such
as more-developed countries, are pyramidal but have fewer young and
reproductive-age individuals and a greater proportion of older individuals. Other
countries that have a zero population growth have a more conical age structure,
with an even greater percentage of middle-aged and older individuals.
A country with a stable population has nearly the same number of individuals
in each age group. A high birth rate and rapidly growing population are indicated
when there is a larger young population compared to the older population. An
ageing population is one with a base that is smaller than the upper parts of the
diagram with a greater population in older, post-reproductive age classes and
low birth rates.
Countries with rapidly growing and shrinking populations can have a problem
with their dependency ratio (the number of non-working individuals compared
to working individuals). In rapidly growing populations, each working person
supports a high number of children while in shrinking populations, a small
number of working persons support a larger number of retired persons.
The demographic transition model (based on patterns of European countries)
shows the changes in the patterns of birth and death rates that typically occur
as a country moves through the process of industrialisation or development.
According to this model, as a country's economy changes from preindustrial to
post-industrial, low birth and death rates replace high birth and death rates. This
model does not fit all countries or regions exactly and the rate of demographic
transition also varies. Here is a summary of its four stages:
Stage I – the preindustrial stage
o Both birth and death rates are high.
o This stage is related to disease, potential food scarcity and lack of good
health care.
o Society is likely based upon agriculture and most people grow their own
food (risk of food shortages and famine from droughts and floods).
o In large families, children form part of the family workforce.
Stage II – the industrialising/urbanising stage
o This stage is marked by falling death rates as a country develops and
from medical advances, sanitation improvements and food production
increases.
o People live longer and childhood mortality drops (women still have many
children, however more live into adulthood).
8
•
•
•
•
•
•
•
•
•
o The birth rate is still higher than the death rate, so the population growth
rate is high and the population size increases rapidly.
Stage III – the mature/industrial stage
o This stage is marked by falling birth rates as a country continues to be
industrialised and many women join the workforce.
o Raising children becomes more expensive, children no longer work for
the family and individuals may have access to birth control and choose
to have fewer children, leading to lower birth rates and smaller families.
o Death rates continue to drop as medicine, sanitation and food security
continue to improve.
o Birth rates are still higher than death rates, meaning that population
growth is still high and population size continues to increase.
Stage IV – the post-industrial stage
o Birth and death rates drop to low, stable and approximately equal levels.
o Low death rates are related to medical advances, good sanitation, clean
drinking water and food security.
o Low birth rates are related to access to birth control, the education of
women, and women in the workforce delaying marriage and having
children later.
o Low childhood mortality, high life expectancy and family sizes of
approximately two children per couple.
o The population growth rate is approximately zero.
Life expectancy is the average number of years that a person in a particular
population is expected to live (average age at death).
As a country moves through the demographic transition model, life expectancy
increases. Overall, life expectancy has increased for most countries and
regions over the past 100 years. However, there is still a significant variation in
different parts of the world.
The main cause of population growth has not been increased fertility but rather
declining death rates due to better food and sanitation.
Fertility describes the actual production of offspring.
The crude birth rate is the number of births in a year per thousand people.
Total fertility rate (TFR) is the average number of children born to each woman
in a population, over the woman's life span (generally determined by health
care, education, economic conditions, culture and religion). These factors
determine a country's desired fertility (the average number of children the
average couple wants to have), which in turn influences the TFR. Factors that
increase people's desire to have children are known as pronatalist pressures.
Countries in stages I and II of the demographic transition have higher TFR,
which decreases considerably as the countries move to stages III and IV.
9
•
•
•
Other factors that result in high TFR include poverty; the need for children to
work on farms, do chores, and care for parents as they age; and lack of access
to contraception. Other factors that influence TFR include urbanisation, social
security and educational opportunities.
Overall, fertility rates have decreased for most countries and regions over the
past 50 years; however, there is still a significant variation among different parts
of the world.
Zero population growth (neither increasing nor decreasing) occurs when the
number of people born (birth rate) equals the number of people dying (death
rate). Zero population growth is realised when the population reaches the
replacement fertility rate (every couple only has enough children to replace
themselves). The global replacement fertility rate is currently estimated to be
2.1 children per woman.
THE GREAT ACCELERATION
Instructions
• Watch the following video:
https://www.youtube.com/watch?v=7EZvECP86dg (2:00 minutes)
Purpose
• The video "The Great Acceleration" is a short illustration of human population
growth, demographic transition and the changes in human society that has
led to a greater impact on Earth.
6.4.3 How do environmental conditions impact the human population?
Study chapter 6.1 in Fisher (2018).
Summary
• Huge amounts of pollutants and toxic waste
are dumped into Earth's biosphere without full
consideration of the impact on the health and
wellbeing of Earth's ecosystems and human
populations.
• For most of human history, biological agents were the most significant health
factor. These include pathogenic (disease-causing) organisms such as
bacteria, viruses, protozoa and internal parasites.
• In modern times, cardiovascular diseases, cancer and accidents are leading
killers in most parts of the world. However, infectious diseases influenced by
malnutrition, poor water, sanitation and medical care, still cause about 22
million deaths a year in mostly undeveloped countries (affects mostly children).
• Chemical agents such as toxic heavy metals, dioxins, pesticides and endocrine
disrupters also have significant effects on human health. The pesticide DDT
was widely used for decades and seen as ideal since it is inexpensive and
10
breaks down slowly in the environment. However, this causes this chemical
agent to biomagnify through the food chain (become more concentrated in
species with increasing food chain levels). Populations of bird species at the
top of the food chain, such as eagles, are greatly affected by DDT in the
environment.
6.4.4 What is environmental health?
Study chapter 6.2 in Fisher (2018).
Summary
• Environmental health is concerned with preventing disease, death and disability
by reducing exposure to adverse environmental conditions and promoting
behavioural change. It focuses on both direct and indirect causes.
• Environmental health risks can be grouped into two broad categories, namely
traditional hazards and modern hazards.
• Traditional hazards relate to poverty and lack of development that mostly affect
developing countries (like water-related diseases caused by inadequate water
supply and sanitation).
• Modern hazards (like air pollution) are caused by technological development
and prevail in industrialised countries where exposure to traditional hazards is
low. The contribution of modern environmental risks to the disease burden in
most developing countries is similar to, and in quite a few countries, greater
than that in developed countries. Poorer people increasingly experience a
double burden of traditional and modern environmental health risks.
• Worldwide, the top killers of children under five are acute respiratory infections
(from indoor air pollution), diarrheal diseases (mostly from poor water,
sanitation and hygiene) and infectious diseases such as malaria. Children are
especially susceptible to environmental factors that put them at risk of
developing illness early in life. Malnutrition (a condition that occurs when the
body does not get enough nutrients) is an important contributor to child
mortality.
• Antimicrobial agents have been used for the last 70 years to treat patients who
have infectious diseases. However, as they have been used widely and for so
long, the infectious organisms the antibiotics are designed to kill, have adapted
to them, making the drugs less effective. Antibiotic resistance occurs when
bacteria change in a way that reduces the effectiveness of drugs, chemicals or
other agents designed to cure or prevent infections and is caused by the
process of evolution through natural selection.
11
ACTIVITY 6.2: ENVIRONMENTAL HEALTH AND MY
COMMUNITY
Instructions
• Go to the Blog tool on the GGH1503 module site.
• Reply to the blog post entitled "Activity 6.2: Environmental Health and My
Community" by following the task outlined below.
Purpose
To provide a platform of personal reflection on how the health of the environment
impacts the human population. Consider how the natural environment determines
health of your community. This will expand your knowledge on the complex
interrelationships between human society and environmental quality.
Task
In your blog post, share with fellow students:
1. whether there are any traditional or modern hazards affecting your
community at present, and if so,
2. what these hazards are, how they impact the health of the community, and
what is, or can, be done to reduce both adverse human and environmental
health effects.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
6.4.5 What is environmental toxicology?
Study Chapter 6.3 in Fisher (2018)
Summary
• Environmental toxicology is the scientific study of the health effects associated
with exposure to toxic chemicals occurring in the natural, work and living
environments. It also describes the management of environmental toxins and
toxicity and the development of protection for humans and the environment.
• There are three main routes of exposure through which a chemical can get into
the human body and cause health problems. They are (1) breathing or
inhalation, (2) skin or eye contact and (3) swallowing or ingestion. Once
chemicals enter the body, some move into the bloodstream and reach internal
target organs. Chemical substances take a variety of forms including solids,
liquids, dust, vapours, gases, fibres, mists and fumes, and can also change
form.
•
•
A contaminant refers to hazardous substances, pollutants, pollution and
chemicals. An acute effect of a contaminant occurs rapidly after exposure to a
large amount of that substance. A chronic effect results from exposure to small
amounts of a substance over a long period.
The effect of a certain chemical on an individual depends on the dose (amount);
this relationship is often illustrated by a dose-response curve.
12
•
•
•
The contamination of the air, water or soil with potentially harmful substances
can affect any person or community. Contaminants are often chemicals found
in the environment in amounts higher than what would occur naturally. We can
be exposed to a variety of residential, commercial and industrial sources.
Sometimes, harmful environmental contaminants occur biologically.
Examples of common contaminants include (1) arsenic – a naturally occurring
element that is normally present in our environment in water, soil, dust, air and
food; (2) mercury – a naturally occurring metal and useful chemical in some
products released through the combustion of coal with a potential health risk;
(3) Bisphenol A (BPA) – a chemical synthesised in large quantities for use
primarily in the production of polycarbonate plastics and epoxy resins; (4)
phthalates – a group of synthetic chemicals used to soften and increase the
flexibility of plastic and vinyl; (5) lead – a metal that occurs naturally in the rocks
and soil of Earth's crust, produced from the combustion of coal, oil, gasoline
and natural gas, mining and used in manufacturing such as paint; and (6)
formaldehyde – a colourless, flammable gas or liquid that has a pungent,
suffocating odour.
Radiation is energy given off by atoms and is all around us. We are exposed to
radiation from natural sources like soil, rocks and the sun as well as man-made
sources like medical X-rays and smoke detectors. Radon is a radioactive gas
that is naturally occurring, colourless and odourless that comes from the natural
decay of uranium or thorium found in nearly all soils.
INTRODUCING GEOGRAPHIC TOOLS AND MAPS
Introduction to Geographic Information Systems (GIS)
GIS is "a computer-based system to aid in the collection, maintenance, storage,
analysis, output, and distribution of spatial data and information" (Bolstad, 2019:2).
We use GIS for many applications ranging from studying the environment, the
impact of climate change, town and regional planning, mapping settlement growth,
managing disaster responses, to determining the accessibility to health facilities and
creating tourist maps.
For an introduction, watch the following videos:
• https://www.esri.com/videos/watch?videoid=y9ptLTiJT6g&title=seeing-thefuture-through-gis
• https://www.youtube.com/watch?v=_D530jGd-R0
• https://www.youtube.com/watch?v=6AlH5TvFoLw
• A South African example: https://www.youtube.com/watch?v=9fpJSY-ENh4
For this module, we will use QGIS, a free open-source software (FOSS) geographic
information system that became available in 2009. QGIS can operate on Apple Mac,
Microsoft Windows computers and laptops, as well as on computers and laptops
using Linux and Unix operating systems. The newest version is QGIS 3.20. We will
use QGIS 3.16, which is the long-term release (LTR). LTRs are the most stable
13
versions of QGIS. You must download this version from Google Drive for Apple Mac
and Microsoft Windows using the following link:
https://drive.google.com/drive/folders/1iD7tD11KzktnChfh__0leed2YOc9oqoF?usp
=sharing. There are two versions for Microsoft Windows computers and laptops.
The default installer is the file ending with x86_64.exe; however, if it does not work
on your computer or laptop, you need to use the file ending with x86.exe (for older
computers and laptops).
The user guide for QGIS 3.16 Hannover is also available on Google Drive. For this
module, please read chapters 3, 4, 5, 6, 7 and 8 to familiarise yourself with QGIS.
To install QGIS, you need to download the .exe file from Google Drive. It is easier
to download the file from Google Drive than from the QGIS website. Once you have
downloaded the .exe file from Google Drive, double click on the .exe file and follow
the default installation process for your laptop or computer. You do not need to
change any parameters. You do not need the QGIS sample data. Furthermore, if
you continue with second- and third-year Geography, some of the modules will use
QGIS as well.
We will use QGIS in the capstone activity.
6.5 CAPSTONE ACTIVITY
LEARNING UNIT 6: CAPSTONE ACTIVITY
Instructions
• Go to the Discussions tool on the GGH1503 module site.
• Go to the topic entitled Learning Unit 6: Capstone Activity.
• Reply by providing your response on the tasks detailed below.
Population map of South Africa
14
Purpose
To guide you in becoming familiar with and using QGIS while creating a population
map of South Africa at municipal level using the 2011 Census data. It equips you to
meet the second and third learning outcomes of the module (as listed in the module
overview) by providing you with the tools to explore our human populations.
Task instructions
For this activity you will need QGIS, spatial data and population data to create a
population map of South Africa. Download the step-by-step instructions for this
activity from the module site (Learning Unit 6 Capstone Activity.pdf).
Task
1. Download the spatial data (all the files starting with MN_SA_2011.).
2. Download the population in the file MunicipalityPopulationCensus2011.txt.
3. Open QGIS.
4. Carefully follow the step-by-step instructions.
5. You should end up with something similar as shown in the map above.
6.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
6.6.1 Which option is true about a country experiencing zero population growth?
A. It is most likely in stage 1 of the demographic transition.
B. It is most likely in stage 4 of the demographic transition.
C. It is most likely economically underdeveloped.
D. It is most likely experiencing higher death rates than birth rates.
6.6.2 Which main features marked the Agricultural Revolution?
6.6.3 Of which agent is the pesticide DDT an example?
A. Biological agent
B. Atomic agent
C. Chemical agent
D. Inorganic agent
6.6.4 In terms of environmental health, what is the difference between traditional
and modern hazards?
15
6.6.5 What are the three main routes of exposure through which a chemical can
get into the human body and cause health problems?
6.7 CONCLUSION
Upon completion of this learning unit, you should know the basics of demography and
the study of human population dynamics. You will have gained an awareness of the
interdependence of the health of human populations and the health of the
environment. Human populations cannot grow and thrive without the support of Earth's
natural capital and the environment cannot function properly without the sustainable
use of and lowered human impact on Earth's resources and services. Now that you
have reached the end of learning unit 6, you may proceed to learning unit 7.
6.8 REFERENCES
Bolstad, P. 2019. GIS fundamentals: a first text on geographic information systems
(6th Edition). Ann Arbor: XanEdu.
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Ganivet, E. 2020. Growth in human population and consumption both need to be
addressed to reach an ecologically sustainable future. Environment, Development
and Sustainability, 22:4979-4998.
Henderson, K. & Loreau, M. 2018. An Ecological theory of changing human
population dynamics. People and Nature, 2019 (1):31-43.
Lidicker, W.Z. 2020. A Scientist's Warning to humanity on human population growth.
Global Ecology and Conservation. Available at:
https://doi.org/10.1016/j.gecco.2020.e01232.
Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
16
GGH1503
Learning Unit 7
THE FOOD, ENERGY, WATER NEXUS
Contents
7.1
INTRODUCTION ...................................................................................................................... 1
7.2
AIM AND LEARNING OUTCOMES ........................................................................... 3
7.3
PRESCRIBED MATERIAL......................................................................................... 4
7.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL ............ 6
7.4.1
What is food security and what role do biotechnology and genetic
engineering play? ............................................................................................................ 6
7.4.2
What is the difference between conventional and sustainable agriculture? 9
7.4.3
Energy use and its challenges and impacts .................................................. 10
7.4.4
What is non-renewable energy? ..................................................................... 10
7.4.5
What is renewable energy? ............................................................................ 11
7.4.6
Freshwater supply and the water cycle ......................................................... 13
7.4.7
Water usage, scarcity, and sustainable solutions ........................................ 15
7.5
CAPSTONE ACTIVITY ............................................................................................ 17
7.6
SELF-TEST .............................................................................................................. 17
7.7
CONCLUSION ......................................................................................................... 18
7.8
REFERENCES ......................................................................................................... 18
LEARNING UNIT 7
THE FOOD, ENERGY, WATER NEXUS
Author: Leani de Vries
Co-authors: Chris Vlok and Peter Schmitz
Academic editor: Kristy Langerman
1
Irrigated agriculture in Ohrigstad, South Africa (Source: Unsplash.com, Wynand Uys)
"Scholars, government scientific research institutions, and public policy-making
entities are increasingly focusing on environmental issues from a food-energy-water
(FEW) nexus perspective. This nexus represents the interconnection of these
three systems, which are essential to human life."
(Dreyer et al., 2020:137)
7.1 INTRODUCTION
Food, energy and water are three critical resources that sustain human populations
(Ding, Gunda & Hornberger, 2019). Just think about your typical daily routine. We
require these basic, yet essential, elements to perform daily tasks. In learning unit 1,
you were introduced to the Sustainable Development Goals that aim to address the
social, economic and environmental sustainability challenges of our time. You might
1
All images used in this learning unit are from free, publicly accessible sources.
https://unsplash.com/photos/CgDZmgOBBu8 (Wynand Uys)
https://search.creativecommons.org/photos/97021ad4-79c4-43d2-a0fe-1e835868641a (smith_cl9)
https://search.creativecommons.org/photos/04c90e35-bdb0-4e98-acbe-a9338a61e0a5 (Diogo Martins)
https://search.creativecommons.org/photos/0933eb09-0505-41c5-b949-77f3905a133d (PaulR1800)
1
have noticed that food, energy and water feature directly as SDG 2 (zero hunger),
SDG 6 (clean water and sanitation), and SDG 7 (affordable and clean energy), and
you might have considered the important role they play in the success of the other
SDGs.
While there is more than enough food produced to feed everyone (in fact, food
production is increasing), one in every eight people on Earth are not getting enough
to eat. Not only do people suffer from chronic undernutrition or hunger but many suffer
from malnutrition due to limited diets, The major driver of food insecurity is poverty,
not food availability. Food security requires an adequate, stable supply of food that
also entails economic, social and physical access and fair utilisation. Conventional
food production also poses major environmental concerns and there is a great need
to produce food more sustainably (Fisher, 2018; Miller & Spoolman, 2018; Zehnder et
al., 2018).
Without the continuous flow of energy, no life could exist. Over time, humans have
developed an understanding of energy to harness it for several uses. This has largely
been attributed to the development and evolution of human society. As technology has
advanced over time, the amount of energy utilised by humans has increased
dramatically. We use energy (whether from renewable or non-renewable resources)
for a multitude of purposes, such as lighting, heating and transportation. All energy
resources implicate some environmental and health costs throughout their life cycle;
however, our modern technologies and services are highly dependent on fossil fuels,
leaving our economies and environment vulnerable. Therefore, there is a call for
greater energy efficiency and transition to a more sustainable energy future (Fisher,
2018; Miller & Spoolman, 2018; Zehnder et al., 2018).
Just as we need food and energy, we cannot survive without water. Water is an
essential compound for all living things. Although water covers 71% of Earth's surface,
the human need is for fresh water, which constitutes a very small portion of the total
volume of water on Earth. Although water is renewable and replenished by the water
cycle, fresh water is unequally distributed. Billions of people do not have access to
safe drinking water or proper sanitation, yet fresh water is being wasted, polluted and
overused. The natural shortages of fresh water found across different parts of the
globe are greatly aggravated by this mismanagement of resources. This must be met
with sustainable approaches toward using and enhancing fresh water supply (Fisher,
2018; Miller & Spoolman, 2018; Zehnder et al., 2018).
The food, energy, water (FEW) nexus refers to the critical, intrinsic, interconnection of
these systems. None of these systems can thrive sustainably or stand without the
other (Von Bormann & Gulati, 2014; WWF-SA, 2017; Dreyer et al., 2020). Per
illustration, have a look at the image on the previous page that depicts irrigated
agriculture in Ohrigstad. Consider whether these farmers would have been able to
produce these crops without the use of both energy and water. Any disjoint or failure
2
in a FEW-related resource or service will have an impact on human health and is a
factor of governance, education and economic capacities. Sub-Saharan Africa is
amongst the regions with significant FEW insecurity challenges (Ding, Gunda &
Hornberger, 2019).
South Africa, with its water-dependent economy, is vulnerable to the significant risks
that climate change pose for the future affordability of FEW services. In terms of
energy, for example, the country is facing infrastructure, maintenance and demand
challenges while water stress is another significant risk factor (such as the Cape Town
water crisis of 2017). While the country is supported by adequate legislation and
regulations, compliance and enforcement of these laws and regulations are lacking
and require improvement (Ololade, 2018; Ding, Gunda & Hornberger, 2019).
Addressing challenges related to the FEW nexus is interdisciplinary and requires
contributions from both the social and natural sciences (Dreyer et al., 2020). For this
learning unit, we will zoom in and focus on each of these systems individually, as
opposed to exploring FEW as a nexus itself.
THE FOOD, ENERGY, WATER NEXUS
Instructions
• Watch the following video:
https://www.youtube.com/watch?v=MGNxRZD4Uxs (2:30 minutes)
Purpose
• The video "The Food Energy Water Nexus in South Africa" reminds us that
food, energy and water security are three interconnecting elements that are
critical in sustaining societies.
7.2 AIM AND LEARNING OUTCOMES
This learning unit aims to develop your knowledge of food, energy and water that form
the FEW nexus. It aims to help you understand how human societies are critically
dependent on these three interconnected systems for daily survival and how this
dependence has significant effects on the environment, which necessitates
sustainable solutions. Once you have completed this learning unit, you can use the
outcomes to assess the quality of your learning experience. Assess whether you meet
each aim and outcome with confidence. If not, you are advised to dedicate more time
to those you are still having trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:
•
•
Describe food security and analyse why it is difficult to ascertain.
Discuss the modern methods used to enhance food production and associated
benefits and concerns.
3
•
•
•
•
•
•
•
•
•
•
•
Discuss conventional and sustainable agriculture and their differences.
Describe how food security can be improved sustainably.
Describe the major sources of energy that we currently use.
Discuss the differences between renewable and non-renewable energy.
Compare the advantages and disadvantages of oil, natural gas, coal and
nuclear power as energy sources.
Compare the advantages and disadvantages of solar, wind, hydropower,
geothermal and biomass as energy sources.
Discuss how we can transition to a more sustainable energy future.
Briefly explain the different components of the water cycle.
Describe the major sources of Earth's freshwater supply.
Describe water scarcity and discuss why we have freshwater supply problems.
Identify sustainable solutions to address freshwater supply problems.
7.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from two prescribed
open-access books.
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
•
o
o
Chapter 7: Water Availability and Use
7.1: Water Cycle and Fresh Water Supply
7.2: Water Supply Problems and Solutions
•
o
o
Chapter 8: Food & Hunger
8.1: Food Security
8.2: Biotechnology and Genetic Engineering
•
o
o
Chapter 9: Conventional & Sustainable Agriculture
9.3: Conventional Agriculture
9.5: Sustainable Agriculture
•
o
o
o
Chapter 11: Conventional & Sustainable Energy
11.1: Challenges and Impacts of Energy Use
11.2: Non-Renewable Energy Sources
11.3: Renewable Energy Sources
4
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.
•
o
o
o
o
o
o
o
Chapter 3: Non-Renewable Energy
3.1: What is Energy?
3.2: Fossil Fuels
3.3: Coal
3.4: Oil
3.5: Natural Gas
3.6: Fossil Fuels and Greenhouse Gases
3.7: Nuclear Energy
•
o
o
o
o
o
o
Chapter 4: Alternative Energy
4.1: What is Renewable Energy?
4.2: Solar Energy
4.3: Wind Power
4.4: Hydroelectric Power
4.5: Geothermal Energy
4.6: Biomass Energy
•
o
o
o
Chapter 7: Water
7.3: Global Water Distribution and Use
7.4: The Hydrologic Cycle
7.5.6: Groundwater
•
o
o
Chapter 8: Water Quality
8.2: Water Scarcity and Shortage
8.3: Water Scarcity and Availability
This table summarises the study material for this learning unit.
Relevant sections
Prescribed material
Fisher,
Zehnder et al.,
2018
2018
Chapters 7, 8 & 11
Chapters 3, 4 & 7
7.1, 7.2, 8.1, 8.2, 9.3, 9.5, 11.1,
3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 4.1,
11.2 and 11.3
4.2, 4.3, 4.4 ,4.5, 4.6, 7.3, 7.4, 7.5.6,
8.2 and 8.3
5
7.4 KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 7.2 and will help you to find your way through the study material.
7.4.1 What is food security and what role do biotechnology and genetic
engineering play?
Study chapters 8.1 and 8.2 in Fisher (2018).
Summary
• Many people lack the food they need for an
active and healthy life.
• The major driver of food insecurity is
poverty and not food availability. The main
problem is lack of economic (social and
physical) access to food at national and
household levels and inadequate nutrition
(or hidden hunger).
• Food security requires an adequate supply of food that entails availability,
access and utilisation by all people.
• The four pillars of food security are availability, access, utilisation and stability.
• Those who never have sufficient quality food are chronically food insecure.
• Agriculture and food security are inextricably linked. Staple food crops are the
main source of dietary energy in the human diet (such as rice and wheat).
• While food security can be analysed in numerous ways at national and
household levels, it is only at the individual level that the analysis can be truly
accurate to understand who consumes what.
• Access to food relates, for example, to a country's access to food from the
global market. Food availability is the most important pillar at global level and
relates to whether global agricultural activity produces sufficient food to feed all
the world's inhabitants. Food utilisation essentially translates to the food
available to a household and nutritional security for its members. Food stability
is when a population, household or individual has access to food at all times
and does not risk losing access as a consequence of cyclical events.
• Malnutrition is a form of food instability where there is a lack of essential
nutrients. Obesity, on the other hand, means having too much body fat and is
a significant global health challenge that is preventable and reversible. A global
overweight/obesity epidemic has emerged in industrial countries and now
increasingly in low- and middle-income countries, particularly in urban settings.
6
•
•
•
•
•
•
The development of a new strain of crop is an example of agricultural
biotechnology (a range of tools that include both traditional breeding techniques
and modern laboratory-based methods).
Genetic engineering describes methods that scientists use to introduce new
traits to an organism and results in genetically modified organisms (GMO).
Genetically engineering plants, for example, produce characteristics to
enhance the growth or nutritional profile of food crops (GE crops).
Nearly all the fruits and vegetables found in supermarkets today would not
occur naturally and exist because of human intervention (traditional breeding
practices) that began thousands of years ago. These rely upon selective
breeding (human-assisted breeding of individuals with desirable traits).
While traditional breeding and modern genetic engineering both result in
changes to an organism's genetic information, the magnitude of those changes
varies. Traditional breeding shuffles all the genes between two organisms while
modern genetic engineering is more precise through modifying or introducing
just a single gene between two distantly related species.
Potential benefits of genetic engineering include enhanced nutrition, cheaper
and more manageable production, and improved pest control. Potential
concerns include environmental hazards, long-term ecological risks and human
health risks.
Significant financial and intellectual resources have been allocated to
determine whether GE crops are safe. While it has been accepted that GE
crops are safe, a debate still revolves around whether they are necessary.
EXTRACT FROM THE EXPERTS
Sue Northam-Ras, WWF South Africa's communications manager for
environmental programmes, writes:
Nature provides many vital ecosystem services when it is able
to perform in a healthy, functioning state. These include clean
water, nutrient-rich food to eat, air to breathe, and pollination.
However, many human activities have caused severe
pressures and negative impacts. Our food system has done
more damage to the natural environment than any other human
enterprise. The way in which we currently produce food
threatens both the environment and human health. We need to
ensure a resilient and regenerative food system, a healthy
environment and access for all to nutritious food. It's also time
we paid greater attention to the food system and how it impacts
on the biodiversity which exists within nature.
WWF works across various value chains and sectors, and at
multiple levels of engagement with communities and the private
sector, as well as at a policy and public level. We work to enable
food, energy and water security as well as ensuring that
7
conservation-worthy natural areas are regenerated or
maintained, and not further degraded. In the realm of food
systems in South Africa, WWF works across the food value
chain. At a primary resource level, we focus on efforts in critical
biomes such as the Cape Floral Kingdom, Succulent Karoo and
the Grasslands. In these water-critical and biodiversityabundant areas, we work with willing small-scale producers and
commercial farmers, as well as relevant associations. WWF
guides on best practice in water stewardship and energy
efficiency. This includes reducing water use and improving
environmental freshwater flows by clearing water-thirsty
invasive alien plants in strategic water source areas.
As a water-scarce country, and with the changing climate which
is resulting in more frequent periods of drought as well as other
extreme weather events, the water footprint in South Africa's
farming and food production value chain is an essential element
in the interrelated food-energy-water ''nexus''.
Avoiding and reducing food waste is another area where we
can make a positive collective impact. Not only is wasted food
in stark contrast to the millions of South Africans going hungry
every day, there are also many environmental implications. The
embedded water and energy in the discarded food, together
with the cost of disposing of unused food, means that food
waste comes at a high price to both the South African economy
and the environment.
Due to the negative impacts from many forms of production and
mass consumption, food water and energy are therefore three
critical areas for focus and intervention to ensure a future in
which nature and people thrive. From a global perspective, the
food-energy-water nexus relates to Sustainable Development
Goals 2 (Zero Hunger), 6 (Clean water and sanitation) and 7
(Affordable and clean energy) amongst others.
See the following related WWF reports:
• 2019 WWF Agri-food Systems: Facts and Futures
• 2017 WWF food-water-energy nexus for delivering on the SDGs
FOOD SECURITY AND WHY IT MATTERS
Instructions
• Watch the following video: https://youtu.be/WP3G6TyboHo (1:57 minutes)
Purpose
• The video "Global Citizen: Food Security" introduces food security and why
it matters. This will help to contextualise the theory that you are learning in
this learning unit.
8
7.4.2 What is the difference between conventional and sustainable
agriculture?
Study chapters 9.3 and 9.5 in Fisher (2018).
Summary
• Conventional farming, also known as modern agriculture or industrial farming,
is the prevailing agricultural system that has delivered tremendous gains in
productivity and efficiency over the past 50 years.
• Conventional farming practices include rapid technological innovation, large
capital investments, large-scale farms, single crops (monocultures), uniform
high-yield hybrid crops, dependence on agribusiness, mechanisation of farm
work, and extensive use of pesticides, fertilisers and herbicides.
• While there are several positive consequences, some concerns include (1)
ecological concerns such as soil salinisation and desertification, (2) economic
and social concerns such as widening disparity among the income of farmers,
(3) potential human health concerns such as the contamination of food and
water by pesticides and nitrates, and (4) philosophical considerations such as
a declining proportion of the population producing food leading to little
connection with natural processes that produce food.
• Sustainable agriculture is the integrated system of plant and animal production
that will satisfy human food and fibre needs, enhance environmental quality,
make efficient use of non-renewable resources and on-farm resources while
integrating natural biological cycles and controls, sustain the economic viability
of the farm and enhance the quality of life of farmers and society as a whole.
• Organic agriculture is an ecological production management system that
promotes and enhances biodiversity, biological cycles and soil biological
activity. Organic agriculture emphasises the use of renewable resources and
the conservation of soil and water to enhance future environmental quality, thus
does not use most conventional synthetic pesticides and fertilisers.
• Organic agriculture uses resources that are independent of fossil fuels, are
locally available, incur minimal environmental stresses, and are cost effective.
• Integrated Pest Management (IPM) refers to a mix of farmer-driven, ecologically
based pest control practices that seek to reduce reliance on synthetic chemical
pesticides. Biological control (biocontrol) is the use of one biological species to
reduce populations of a different species. Intercropping means growing two or
more crops in close proximity to each other during part or all of their life cycles
to promote soil improvement, biodiversity and pest management.
• Modern agricultural practices use heavy machinery to prepare the seedbed for
planting, to control weeds and to harvest the crop. While this has many
advantages, it can cause soil compaction and disrupt natural soil organisms.
Alternative practices encourage minimal tillage or no-tillage methods that can
limit compaction, protect soil organisms and have other benefits. It is used
successfully in areas such as Latin America and Africa.
9
•
Crop rotations are planned sequences of crops over time on the same field that
provide production benefits such as improved soil nutrient levels.
7.4.3 Energy use and its challenges and impacts
Study chapter 11.1 in Fisher (2018) and chapter 3.1 in Zehnder et al. (2018).
Summary
• Living organisms need energy to survive and perform life-sustaining 'work'. For
nearly all living systems on Earth, the sun is the ultimate source of that energy.
Over time, humans have developed an understanding of energy to harness it
for several uses (largely contributed to the development of human society).
• The energy we use for lighting, heating, cooling our buildings, manufacturing
products, and transportation systems come from a variety of natural resources.
Energy can be defined either as renewable or non-renewable. Renewable
energy sources can be replenished within human lifespans (e.g., solar, wind
and biomass) while non-renewable energy is finite and cannot be replenished
within a human timescale (e.g., nuclear energy and fossil fuels).
• All energy sources implicate some environmental and health costs throughout
their life cycle, and energy is also not distributed equally across all nations.
Environmental and health impacts can occur during extraction, processing,
purification or manufacturing, transportation to the place of energy generation,
combustion and the disposal of energy waste. While the use of fossil fuels has
led to a higher standard of living for the global population, our modern
technologies and services are highly dependent on fossil fuels that implicate
vulnerable economies should supplies become limited or extremely costly.
• Some of the most distinct characteristics of modern civilisation, including
population growth, environmental impact and climate change are all a
consequence of energy use.
7.4.4 What is non-renewable energy?
Study chapter 11.2 in Fisher (2018) and chapters 3.2, 3.3, 3.4, 3.5, 3.6 and 3.7 in
Zehnder et al. (2018).
Summary
• Fossil fuels including oil, coal and natural gas originate from the organic matter
(biomass) of plants, algae and cyanobacteria that were buried, heated and
compressed under high pressure over millions of years.
• Oil (petroleum):
o Usually found 1.6 to 3.2 km below Earth's surface (whether land or
ocean). Once extracted, oil must be refined. Other sources of oil include
tar sands and oil shale.
o When burnt for energy, it produces emissions (carbon dioxide, sulphur
dioxide, nitrous oxides, particulate matter and lead) that have
detrimental effects on the environment and human health.
10
• Coal:
o The high consumption of coal is attributed to its relatively low cost and
abundance.
o However, its extraction, transportation and use produce a multitude of
environmental impacts that are not truly represented in the market cost.
o Emissions include sulphur dioxide, nitrogen oxide and mercury that are
linked to acid rain, smog and health issues.
• Natural gas:
o Mainly composed of methane.
o There are two types of natural gas including biogenic gas (found at
shallow depths and arises from anaerobic decay of organic matter by
bacteria) and thermogenic gas (from the compression of organic matter
and deep heat underground).
• Nuclear power:
o The energy released from the radioactive decay of elements, such as
uranium that releases large amounts of energy.
o Since nuclear power plants produce no carbon dioxide, they are often
considered an alternative fuel.
o Environmental challenges with nuclear power include high energy
demands for mining and refining. While it does not produce carbon
emissions, it does produce dangerous waste that must be stored
correctly and can have accidental leaks of long-lived radiation.
7.4.5 What is renewable energy?
Study chapter 11.3 in Fisher (2018) and
chapters 4.1, 4.2, 4.3, 4.4, 4.5 and 4.6 in
Zehnder et al. (2018).
Summary
• Renewable energy sources are often
considered alternative energy sources
while non-renewable energy sources are
considered conventional energy sources.
• Renewable energy from the sun and wind are considered an unlimited or
'completely renewable supply' while other sources that can theoretically be
replenished at least as quickly as they are consumed, are semi-renewable
resources.
• Renewable energy sources that do not emit greenhouse gases, may be the key
to limiting environmental impacts related to global climate change. World
energy demand and consumption continues to rise in emerging economies
such as China and India while the growth in demand has slowed in
industrialised countries with stabilising or shrinking population sizes.
11
•
•
•
•
Solar energy:
o Has been used for centuries to heat homes and water.
o Modern technology includes photovoltaic cells (PV).
o Downsides include that it is not evenly distributed across the globe and
that it can only be gathered when the sun is shining.
o Passive solar power manipulates the sun's energy to provide heating or
cooling without the use of special devices or modern technology while
active solar power systems harness the sun's energy through
specialised devices that transform this energy into another form.
o Has minimal impact on the environment depending on its placement.
Wind power:
o Uses the energy of moving air to generate electricity.
o The most common form of wind power is wind turbines (traditionally,
used for hundreds of years as windmills) that do not release emissions
and do not require water for cooling. There are however certain
environmental impacts, such as aesthetic concerns, leaks, noise
pollution, and bird and bat deaths.
Hydropower (hydroelectric):
o Relies on water to spin turbines and create electricity.
o Has been used for hundreds of years when the kinetic energy from
moving water was used to turn a mill or grind grain.
o Most types require regions with rivers that are large enough and have a
flow strong enough to support a hydropower station.
o Most commonly in the form of storage hydropower (dams and reservoir
systems), while other approaches include pumped-storage hydropower,
run-of-river hydropower and tidal power.
o While hydropower is renewable and does not produce direct emissions
of air pollutants, it does contribute to serious environmental impacts such
as the obstruction of fish migration from hydropower dams and
reservoirs.
Geothermal energy:
o Uses heat from Earth's subsurface (internal geological processes) to
produce electricity or provide heating.
o Wells are drilled in a location with high geothermal potential. The wells
bring superheated water or steam to the surface, where heat energy is
converted into electricity by a generator at a geothermal power plant or
wells are dug to tap the steam reservoir to bring it to the surface to drive
turbines and produce electricity.
o Environmental impacts are minimal and depend on its use. For example,
direct use and heating applications have almost no negative
environmental impacts.
12
•
Biomass energy:
o The energy is stored in materials of biological origin such as plants and
animals and is the oldest energy source used by humans.
o It includes direct combustion of solid biomass, converting biomass into
liquid biofuels, or biomass energy harvested through gaseous biomass,
sometimes called biogas.
o It is a challenge to determine whether biomass is a more sustainable
option. To be sustainable, it must come from waste material.
ACTIVITY 7.1: ENERGY SOURCES USED IN MY LOCAL
AREA
Instructions
• Go to the Blog tool on the GGH1503 module site.
• Reply to the blog post entitled "Activity 7.1: Energy Sources used in my Local
Area" by following the task outlined below.
Purpose
To create a platform where you can reflect on the variety of energy sources used in
your local area and in your home. This will help you gain an understanding of our
dependence on different sources of energy (whether it be renewable or nonrenewable).
Task instructions
Walk, cycle or drive through your village, neighbourhood, suburb, town or city and
make a list of all the different sources of energy that you see. Then add to this list,
the types of energy sources used in your home.
Task
In your blog post, share with fellow students:
1. the list of energy sources observed in your local area and in your home, and
2. whether you think your local environment is more dependent on nonrenewable or renewable energy sources.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
7.4.6 Freshwater supply and the water cycle
Study chapter 7.1 in Fisher (2018) and chapters 7.3, 7.4 and 7.5.6 in Zehnder et
al. (2018).
Summary
• Water is an essential compound for all living things. Humans require water for
oxygen and food supply. We also cannot survive without water for longer than
a few days. Clean water for all people is a critical environmental goal.
• Considering the abundance of water on Earth's surface (± 71%), Earth is
considered the 'water planet'. Around 97% of this is salty ocean water
(unavailable for human consumption). Ice caps and glaciers are the largest
reservoirs of fresh water (± 2%) but are inconveniently located. Around 97% of
fresh water is groundwater and less than 1.4% of Earth's water is in the form of
surface water (lakes and rivers are our most used water sources).
13
•
While water is renewable and replenished by the water cycle, water availability
is unevenly distributed over Earth. Many areas experience extreme water
shortages because of factors such as climate change, population growth,
overuse of water and water pollution. This leads to billions of people without
safe drinking water and adequate sanitation.
•
The water (hydrological) cycle (introduced in learning unit 3) shows the
continuous movement of water from one reservoir to another, which include the
oceans, atmosphere, ice caps and glaciers, groundwater, lakes and rivers. This
is driven by solar energy and gravity.
The components of the water cycle include evaporation (water changing from
liquid to gas or vapour), precipitation (water falling from clouds such as rain and
snow), transpiration (loss of water by plants to the atmosphere), condensation
(water changing from gas to liquid), surface runoff/flow (precipitation travelling
over the surface to the nearest stream channel) and streamflow (movement of
water in a natural channel).
Earth's primary freshwater resources as part of the water cycle include:
o Precipitation
Precipitation levels are unevenly distributed across the globe and affect
freshwater availability (e.g., more precipitation falls near the equator).
Rainfall and climate patterns are related to global wind circulation cells,
the size of the continents, ocean currents, and mountains.
o Surface water resources (rivers, lakes, glaciers)
Water from rain and melted snow flow enter river channels through
surface runoff and groundwater seepage. The relative contributions of
each to river discharge (volume of water moving through a river channel
over time) depends on precipitation patterns, vegetation, topography,
land use and soil characteristics. The geographic area drained by a river
and its tributaries is called a drainage basin (watershed). Other surface
water resources include lakes and artificial lakes (reservoirs by damming
rivers). Melting glaciers also provide a source of river and groundwater.
o Groundwater resources
Groundwater is a significant reservoir of usable fresh water and is
particularly important in arid climates with scarce surface water. Most
groundwater originates from rain or melted snow infiltrating the ground
and moving down through unsaturated rocks or sediment (unsaturated
zone) to the saturated zone (where groundwater completely fills Earth's
pore spaces). The top of the saturated portion is called the water table.
Recharge areas (e.g., wetlands) are locations where surface water
infiltrates the ground rather than running into rivers or evaporating.
Aquifers are large areas of sub-surface, porous rock formations or
sediments that store and yield water often used for agricultural and
domestic uses and accessed through drilling holes (wells).
•
•
14
ACTIVITY 7.2: WORLD WATER USAGE METER
Instructions
• Use the following link to explore the current global water usage:
https://www.worldometers.info/water/
• Follow the changing figures on the worldometer website that tracks the global
water usage and water usage by country.
• Go to the Blog tool on the GGH1503 module site.
• Reply to the blog post entitled "Activity 7.2: World Water Usage Meter" by
following the task outlined below.
Purpose
To expose you to the significant growing trends in the world's water demand. With
the knowledge of limited usable fresh water, you will understand the importance of
conserving and using water sustainability to meet our present and future needs.
Task
In your blog post, share with fellow students:
1. the country with the highest water usage on the day you visited the website,
and
2. your thoughts on how water usage differs between more-developed and lessdeveloped countries using the information from the website.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on the posts of other students.
7.4.7 Water usage, scarcity, and sustainable solutions
Study chapter 7.2 in Fisher (2018) and chapters 7.3, 8.2 and 8.3 in Zehnder et al.
(2018).
Summary
• The increase in global water demand
beyond the rate of population growth is
due to an improved standard of living
without an offset of water conservation.
• Major global water uses include
irrigation (agricultural sector), public
supply (domestic sector) and industries
(industrial sector).
• Non-consumptive use is when water is removed from its source and then
returned to the source after use (e.g., industrial cooling), while consumptive use
is when water is taken from a source and consumed without returning to the
source (e.g., irrigation).
•
Groundwater, rivers, lakes, artificial lakes (reservoirs) and glaciers can be
depleted over time.
o Groundwater pumping usually causes a localised drop in the water table
around the well, called a cone of depression. When the regional water
table drops significantly due to many wells, this is called groundwater
15
•
•
•
•
•
mining and forces the drilling of deeper, more expensive wells. Saltwater
intrusion is another concern associated with groundwater mining near
ocean coastlines where saltwater enters freshwater zones. Water table
drops may also cause land subsistence and sinkholes.
o Rivers, lakes and reservoirs can be depleted due to overuse and some
rivers may also run dry.
o Glaciers are depleted due to accelerated melting from global warming.
A water crisis is a global situation where many people lack access to sufficient
and clean water. It is one of the major environmental crises we face today.
Water shortages are also called water stress and are generally greatest in
areas with low precipitation and/or large population densities. This water crisis
could worsen in the future due to global warming. Water crises have a direct
impact on food production and can fuel future global conflict and tension.
So, while there is enough fresh water on Earth to supply every person, the main
problems are that it is unevenly distributed, polluted, mismanaged and wasted.
People living in more-developed countries tend to have more access to safe
drinking water (even if the regions are water scarce). On the other hand, areas
with large water supplies may also be water scarce if there are lacking financial
resources and infrastructure to supply clean and safe drinking water.
Water scarcity happens when the demand for water or a certain quality is
greater than the supply and can be either physical or economic. Physical water
scarcity is when there is an actual shortage of water regardless of quality or
infrastructure while economic water scarcity is when there is a lack of financial
resources and/or infrastructure to supply safe drinking water.
There are multiple approaches toward enhancing freshwater supply and
moving towards sustainability.
o Reservoirs
Reservoirs that form behind dams in rivers can collect and store water
for urban water supplies. Other uses include hydroelectricity, flood
control and recreation.
o Aqueducts
Aqueducts move water from where it is plentiful to where it is needed;
however, it can be controversial and politically challenging. Water
diversion can also cause drought in the area where the water is drawn.
o Desalination
Desalination aims to increase the amount of fresh water by removing
dissolved salt from seawater or saline groundwater. There are numerous
methods such as boiling, filtration and electrodialysis. All desalination
methods are moderately to very expensive, require considerable energy
input, and highly saline wastewater must be disposed of, which has a
significant environmental impact.
16
o Conservation
Conservation means using less water and using water more efficiently.
This may involve different engineering features or behavioural decisions.
Some examples include rainwater harvesting (catching and storing
rainwater for reuse) and efficient irrigation (such as drip systems).
7.5 CAPSTONE ACTIVITY
LEARNING UNIT 7: CAPSTONE ACTIVITY
Instructions
• Go to the Discussions tool on the GGH1503 module site.
• Go to the topic entitled Learning Unit 7: Capstone Activity.
• Reply by providing your response on the tasks detailed below.
Purpose
To provide you with the opportunity to apply and develop your knowledge on water
security through the case of the multi-year drought in Cape Town and risk factors in
South Africa. It also equips you to meet the last of the module's three main learning
outcomes (as listed in the module overview) by considering environmental
degradation and actions to reduce the occurrence thereof.
Task instructions
For this activity, you will need to consult the following three websites on drought
risks facing Cape Town and South Africa. Respond to the tasks below.
• https://earthobservatory.nasa.gov/images/91649/cape-towns-water-isrunning-out
• https://earthobservatory.nasa.gov/images/92428/cape-towns-reservoirsrebound
• https://www.nationalgeographic.com/science/article/partner-content-southafrica-danger-of-running-out-of-water
Task
1. Explain what 'Day Zero' means.
2. List three impacts of droughts in South Africa.
3. Discuss three actions a normal citizen could take to conserve water.
For more reports on drought in Africa, using remote sensing technology, visit
https://earthobservatory.nasa.gov/images/event/88589/drought-in-africa.
7.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
17
7.6.1 List and describe the four pillars of food security.
7.6.2 What is genetic engineering? Describe the potential benefits and concerns.
7.6.3 Which statement about non-renewable energy resources is false?
A. Coal has a relatively low cost.
B. The emissions from burning oil for energy leads to detrimental
environmental and human health effects.
C. Natural gas supplies the greatest proportion of the world's energy demand.
D. Nuclear power plants are expensive to build and require a large quantity of
building materials.
7.6.4 What is groundwater mining and what are some of its associated concerns?
7.6.5 Discuss some of the limits of desalination as a solution to increase freshwater
supplies.
7.7 CONCLUSION
Upon completion of this learning unit, you should realise that we as humans cannot
survive without food, energy and water. You should also consider that the proper
sustainable functioning of each of these systems depends on the other. This is what
we call the complex and interconnected food,energy, water (FEW) nexus. Given the
many challenges facing these three systems, it is important that we address them
using sustainable solutions. Sustainable food production, the use of sustainable
energy resources, and the sustainable use and management of water are imperative
to our own survival and Earth's natural capital. What does the FEW nexus mean to
you? Has studying this learning unit perhaps changed your view on your dependence
on the proper and sustainable functioning of these three systems? Now that you have
reached the end of learning unit 7, you may proceed to learning unit 8.
7.8 REFERENCES
Ding, K.J., Gunda, T. & Hornberger, G.M. 2019. Prominent Influence of
Socioeconomic and Governance Factors on the Food-Energy-Water Nexus in subSaharan Africa. Earth's Future, 7:1071-1087.
Dreyer, S.J., Kurz, T., Prosser, A.M.B., Walton, A.A., Dennings, K., McNeill, I.,
Saber, D.A. & Swim, J.K. 2020. Towards a Psychology of the Food-Energy-Water
Nexus: Costs and Opportunities. Journal of Social Issues, 76 (1):136-149.
18
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Miller, G.T. & Spoolman, S.E. 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Ololade, O.O. 2018. Understanding the nexus between energy and water: A basis
for human survival in South Africa. Development Southern Africa, 35 (2):194-2019.
Von Bormann, T. & Gulati, M. 2014. The Food Energy Water Nexus: Understanding
South Africa's most urgent sustainability challenge. WWF-SA, South Africa. Available
at:
https://wwfafrica.awsassets.panda.org/downloads/wwf_few_report_3.pdf?10701/Und
erstanding-South-Africas-most-urgent-sustainability-challenge.
WWF-SA. 2017. The food-energy-water nexus as a lens for delivering the UN's
Sustainable Development Goals in southern Africa. The Worldwide Fund for Nature,
South Africa. Available at:
https://wwfafrica.awsassets.panda.org/downloads/wwf_2017_the_food_energy_wate
r_nexus_as_a_lens_for_delivering_the_uns_sdgs_in_sa_.pdf?21301/food-energywater-nexus-as-lens-for-delivering-UN-SDG-in-SA.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
19
GGH1503
Learning Unit 8
THE AIR WE BREATHE: POLLUTION AND CLIMATE CHANGE
Contents
8.1
INTRODUCTION ...................................................................................................................... 1
8.2
AIM AND LEARNING OUTCOMES ..................................................................................... 2
8.3
PRESCRIBED MATERIAL..................................................................................................... 3
8.4
KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL .............. 4
8.4.1
The atmosphere .............................................................................................................. 4
8.4.2
What is outdoor and indoor air pollution? .............................................................. 6
8.4.3
What is acid rain and why is it a problem? ............................................................. 7
8.4.4
What is ozone and ozone depletion?........................................................................ 7
8.4.5
What is climate change and its effects? .................................................................. 9
8.4.6
How do we slow down and adapt to climate change? ....................................... 10
8.5
CAPSTONE ACTIVITY ......................................................................................................... 11
8.6
SELF-TEST ............................................................................................................................. 12
8.7
CONCLUSION........................................................................................................................ 13
8.8
REFERENCES ....................................................................................................................... 13
LEARNING UNIT 8
THE AIR WE BREATHE: POLLUTION AND CLIMATE CHANGE
Author: Peter Schmitz
Co-authors: Leani de Vries and Chris Vlok
Academic Editor: Kristy Langerman
1
Air pollution during the Industrial Revolution (Source: Wikimedia Commons, Philip James de
Loutherbourg, 1801)
"Air pollution connects us all and has affected every place on the planet's surface."
(Miller & Spoolman, 2018:476)
"A fundamental concern for others in our individual and community lives would go a
long way in making the world the better place we so passionately dreamt of."
(Nelson Mandela, 2008)
8.1 INTRODUCTION
In the previous learning units, you learned about how our living Earth works. From the
scientific basics of energy and matter that constitute us, our environment, and Earth's
processes and systems, to the biological diversity of life on Earth and the inner
workings of our ecosystems. You also learned about how human populations change
and how we play a key role in sustaining our living Earth. Amongst other daily
essentials, we obtain food, energy and water from our environment, yet our history
and current trends indicate that we are not living sustainably. In this learning unit, the
concluding learning unit for the module, we will focus on air pollution and climate
1
All images used in this learning unit are from free, publicly accessible sources.
https://commons.wikimedia.org/wiki/File:Philipp_Jakob_Loutherbourg_d._J._002.jpg (Wikimedia Commons)
https://search.creativecommons.org/photos/d8342a43-74ab-4a31-a226-dfe38c44fe0b (NASA Johnson)
https://search.creativecommons.org/photos/40ba29ab-a695-45dd-b9d1-0bf312da952e (Pulpolux !!!)
https://search.creativecommons.org/photos/7c49b55f-69ca-428f-9268-096ded8d0848 (NASA Goddard Photo and Video)
1
change, two pressing environmental challenges fuelled by unsustainable human
activities.
Air pollution is one of our oldest environmental concerns, from natural phenomena
such as volcanoes and windstorms to when humans first discovered fire. From as early
as the Middle Ages, the thick haze of wood smoke that hung over cities was well known
and well described. While dangerously polluted city air was tolerated for centuries,
people started to realise that it was a problem with serious risks to human health and
implemented stricter regulations and controls. As shown in the painting above, during
the Industrial Revolution that began in the 1700s, coal-burning factories belched huge
volumes of noxious smoke into the atmosphere over cities in North America and
Western Europe (Theodore, 2008).
While the Earth's climate has been changing naturally over its history, scientific
evidence indicates that recent climate change from the time of the Industrial
Revolution is driven by, especially, the large-scale combustion of fossil fuels to meet
our energy needs. The United Nations Framework Convention on Climate Change
(UNFCCC) was established in 1992 to guide negotiations in addressing climate
change. There is great debate in these negotiations over the respective responsibilities
of the Global South and Global North due to the inequalities in historic and current
greenhouse gas (GHG) emissions of these regions. Historically, the Global South has
contributed only a fraction of GHG emissions, yet its nations are the most vulnerable
to climate change and are currently experiencing the greatest harm (Beer, 2014).
As part of the Global South, Africa is projected to have well above average climate
change. With extreme levels of poverty, high population growth and development, the
continent is at great risk (Müller et al., 2014). Climate change is a key concern in South
Africa too, where mean annual temperatures have over the past five decades
increased by at least 1.5 times the observed global average of 0.65°C, and where
extreme rainfall events have increased in frequency (Ziervogel et al., 2014).
8.2 AIM AND LEARNING OUTCOMES
This learning unit aims to explore air pollution, climate change and its consequences
for our living Earth. Firstly, the learning unit discusses the structure and composition
of the atmosphere in which air pollution, weather and climate occur. It then explores
both indoor and outdoor air pollution and the implications associated with acid rain and
ozone depletion. Lastly, the learning unit focuses on climate change, its dire
implications, and measures of slowing down and adapting to climate change. Once
you have completed this learning unit, you can use the outcomes to assess your
learning experience. Assess whether you meet each aim and outcome with
confidence. If not, you are advised to dedicate more time to those you are still having
2
trouble with or do not understand properly.
At the end of this learning unit, you should be able to do the following:








Identify and describe the structure and composition of the atmosphere.
Distinguish between and discuss indoor and outdoor pollution and its effects.
Describe acid rain and its consequences.
Discuss the significance of ozone and the ozone layer in the stratosphere.
Define ozone depletion.
Define global warming and climate change.
Describe how the Earth's temperature and climate are changing.
Discuss climate change mitigation and adaptation.
8.3 PRESCRIBED MATERIAL
The study material for this learning unit includes selected chapters from two prescribed
open-access books.
The following chapters and sub-chapters are important to study:
Fisher, M.R. (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.

o
o
o
o
Chapter 10: Air Pollution, Climate Change, & Ozone Depletion
10.1: Atmospheric Pollution
10.2: Ozone Depletion
10.3: Acid Rain
10.4: Global Climate Change
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D.
2018. Introduction to Environmental Science (3rd Edition). Biological Sciences
Open Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&con
text=biology-textbooks&type=additional or
https://alg.manifoldapp.org/projects/introduction-to-environmental-science.

o
o
o
o
o
Chapter 5: Air pollution
5.1: Composition and Structure of the Atmosphere
5.2: Ozone
5.3: Outdoor Air Pollution
5.4: Indoor Air Pollution
5.6: Acid Rain

Chapter 6: Climate Change
3
o
o
o
6.2: The Science of Climate Change
6.3: Consequences of Climate Change
6.4: Looking Forward: Climate Solutions
This table summarises the study material for this learning unit.
Prescribed material
Fisher,
Zehnder et al.,
2018
2018
Chapter 10
Chapters 5 & 6
Relevant sections
10.1, 10.2, 10.3 and
10.4
5.1, 5.2, 5.3, 5.4, 5.6,
6.2, 6.3 and 6.4
ACTIVITY 8.1: INTRODUCTION TO AIR POLLUTION
Instructions
 Watch the video "Air Pollution 101" by National Geographic:
https://www.youtube.com/watch?v=e6rglsLy1Ys (3:52 minutes).
 Go to the Blog tool on the GGH1503 module site.
 Reply to the blog post entitled "Activity 8.1: Introduction to Air Pollution" by
following the task outlined below.
Purpose
To provide you with a short introduction to the following sections on air pollution.
This will help you with some context when studying the content in this learning unit.
Task
In your blog post, share your answers to the following questions with fellow students:
1. Identify three examples of natural sources of air pollution.
2. List the three categories of air pollution identified in the video.
3. List possible methods to reduce air pollution.
Read the blog posts of other students and engage in meaningful discussion and
learning by commenting on other students' posts.
8.4 KEY THEMES: FINDING YOUR WAY THROUGH THE STUDY MATERIAL
The key themes are specifically tailored to the learning outcomes listed for this learning
unit in section 8.2 and will help you to find your way through the study material.
8.4.1 The atmosphere
Study chapter 5.1 in Zehnder et al. (2018).
Summary
 The atmosphere refers to the blanket of
gases that surrounds Earth and that is held
in place by gravity. The mix of gases forms
a complex system that is organised into
layers.
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The atmosphere consists of several gases; however, the four gases that exist
in the highest quantities are (1) nitrogen (78%) – protects us from burning on
Earth's surface and provides nutrition to living organisms; (2) oxygen (20,95%)
– the life-giving gas that we need for aerobic respiration and combustion; (3)
argon (0,93%) – an inert gas, meaning it is non-reactive, that is used, for
example, in light bulbs and preservation of archival material; and (4) carbon
dioxide (0,03%) – used by plants through photosynthesis and thus sustains life
on Earth as oxygen is created during the process. Water vapour, in some
locations, can make up to 4% of the total volume of gases.
 The atmosphere is divided into four layers based on temperature changes,
chemical composition, movement and the density of gases in the atmosphere.
These are:
o Troposphere – This is where everything climate-wise occurs. The range of
the height of the troposphere is from 6 km (the poles) to about 20 km (at
the equator). On average, the troposphere reaches up to 18 km from sea
level. The temperature drops from about 17ºC at sea level to -51ºC at the
top of the troposphere, the boundary known as the tropopause.
o Stratosphere – The next level reaches up to 53 km from sea level. The
gases are similar but there is virtually no water vapour and around 1 000
times more ozone than the troposphere. This ozone is the good ozone that
protect Earth's surface from harmful UV light from the sun. It also has a
significantly lower density than the atmosphere. The temperature increases
with height, warming up from -51ºC to -15ºC at the stratopause.
o Mesosphere – This layer starts at the stratopause and continues as we
move higher and higher from Earth's surface. There is no ozone, and the
density of nitrogen and oxygen lessens with height. Owing to very few
molecules in the mesosphere to absorb the sun's energy, the temperature
drops rapidly with height in this layer. At the mesopause, about 85 km from
sea level, the temperature is about -100ºC.
o Thermosphere – The last layer starts at about 85 km above Earth's surface
and extends to around 600 km. The gases in this part of the atmosphere
absorb the dangerous shortwave electromagnetic rays of the sun
(ultraviolet and x-ray radiation) and reach temperatures of about 2000ºC.
However, owing to the low number of molecules at these altitudes, there
are not enough molecules to burn our skins.
 Did you know? Outer space starts at an altitude of 100 km. Any pilot that flies
higher than that is an astronaut and not a pilot anymore.
SOME INTERESTING EVENTS THAT OCCURRED IN THE
STRATOSPHERE AND HIGHER
Instructions
 Watch the video of an aircraft that flew close to outer space in the 1960s:
https://www.youtube.com/watch?v=VBnkbeGLGk4 (7:57 minutes)
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Watch the video showing Felix Baumgartner jumping from 39 km above
Earth: https://www.youtube.com/watch?v=raiFrxbHxV0 (9:24 minutes)
 Watch the video showing how a Lego man flies to the edge of space using
a weather balloon: https://www.youtube.com/watch?v=dVhiFU41eK0 (1:31
minutes)
Purpose
 The videos "X-15 Hypersonic Research At The Edge of Space", "Red Bull
Stratos FULL POV | Felix Baumgartner's Stratosphere Jump" and "Lego Man
Flies To The Edge Of Space" are interesting things that people did outside of
the comfort zone of the troposphere.
8.4.2 What is outdoor and indoor air pollution?
Study chapter 10.1 in Fisher (2018) and chapters 5.3 and 5.4 in Zehnder et al.
(2018).
Summary
 Air pollution refers to the gases and particulates in the atmosphere that causes
discomfort or harm to humans and affect the environment and other living
organisms. It can result from either natural processes, such as forest fires, or
human activities, such as emissions from driving vehicles.
 Primary pollutants are released directly from the source into the atmosphere,
thus directly affecting people and/or the environment, while secondary
pollutants need first to react with other chemicals before having an impact
(produced through reactions between primary pollutants and standard
atmospheric compounds).
 There are two main sources of pollution, namely stationary (point) sources that
do not move and mobile (nonpoint) sources of pollution that can move.
Examples of stationary sources include power plants such as South Africa's
coal-fired power plants. Mobile sources include cars and planes to name a few.
 Air pollution is typically separated into two categories namely outdoor air
pollution and indoor air pollution.
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Outdoor air pollution takes place outside of the built environment. Common
outdoor air pollutants include carbon monoxide, ground-level ozone, nitrogen
dioxide, sulphur dioxide, lead and particulate matter. Volatile organic
compounds (VOCs) are carbon-containing chemicals emitted as gases from
natural and human-made sources.
Smog (from the terms 'smoke' and 'fog') is a mixture of air pollutants that often
form over urban areas as a brownish haze. There are two types of smog
including industrial and photochemical smog. The first is formed primarily by
the burning of fossil fuels and the second is formed when sunlight drives
chemical reactions between primary pollutants for automobiles and other
atmospheric compounds.
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Indoor air pollution refers to air pollution incidents within a building such as
houses, office buildings and shops. It poses a greater health risk than outdoor
air pollution given the generally higher concentration of toxic pollutants and the
fact that people generally spend more time indoors.
Inadequate ventilation can increase indoor air pollution since pollutants are not
adequately carried outside of the building or diluted by enough outdoor air.
Outdoor air can enter or leave a building through infiltration, natural ventilation
and mechanical ventilation.
There are many sources of indoor air pollution. In a home, some of the sources
include household cleaning and maintenance products and the combustion of
wood or gas, to name a few. Outdoor air pollution can also enter buildings and
become a source of indoor air pollution.
The risks and causes of indoor air pollution differ in more industrialised and less
industrialised countries given the different use of sources. For example,
cigarette smoke is a primary health risk in the former, while soot and carbon
monoxide is significant indoor air pollutant in the latter.
8.4.3 What is acid rain and why is it a problem?
Study chapter 10.3 in Fisher (2018) and chapter
5.6 in Zehnder et al. (2018).
Summary
 Pure rainfall is slightly acidic and has a pH of
5.6. Precipitation with a pH below 5.6 is
known as acid rain. It contains a mixture of
wet (rainfall, snow, fog) and dry (particulates) deposition (deposited material)
from the atmosphere containing higher than normal amounts of nitric and
sulphuric acids.
 Acid rain forms from both natural sources (e.g. volcanoes) and man-made
sources (emissions of sulphur dioxide and nitrogen oxides from fossil fuel
combustion). Prevailing winds may blow these compounds across national
borders. These gases react in the atmosphere with water, oxygen and other
chemicals to form various acidic compounds such as sulphuric and nitric acid.
 Acid rain causes acidification of lakes and streams and contributes to the
damage of trees and forests. It also accelerates the decay of building materials
and paints.
8.4.4 What is ozone and ozone depletion?
Study chapter 10.2 in Fisher (2018) and chapter 5.2 in Zehnder et al. (2018).
Summary
 Ozone (O3) is a gaseous and relatively unstable molecule occurring in different
parts of the atmosphere. Ozone is created in the stratosphere where the ultraviolet (UV) solar radiation breaks up the oxygen gas (O2) molecule into two
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oxygen atoms. These atoms react with O2 to form ozone. The UV radiation then
gets absorbed by the ozone and the ozone breaks up into O2 and an oxygen
atom (O). This absorption of UV radiation in the stratosphere by the ozone
protects us from this dangerous UV radiation from the sun.
There are two types of ozone (the good and the bad).
The ozone created in the stratosphere is good ozone since it protects us from
the harmful UV-C radiation. Even though ozone does protect us from harmful
UV radiation, we cannot go without appropriate protection against the sun's UV
radiation since the ozone does not absorb high levels of UV-A radiation and
does not absorb all the UV-B radiation.
Bad ozone is the ground-level ozone in the troposphere that is a significant
hazard to human health. The ozone at ground level originating from vehicle
exhausts and other anthropogenic emissions can be hazardous when at higher
levels of concentration in the troposphere.
The ozone layer is the portion of the stratosphere at about 17 km to 30 km
above sea level with the highest concentration of ozone molecules that protects
life on Earth from harmful UV light.
Global ozone concentrations change periodically with regular natural cycles
such as changing seasons and winds. Ozone depletion occurs when the
dynamic balance between the creation and destruction of ozone is disrupted.
Ozone reacts very easily with other chemical elements or compounds.
Chlorofluorocarbons (CFCs) (that were used in industry as refrigerants,
degreasing solvents, and propellants) and other ozone-depleting substances
(ODS) can destroy ozone molecules in the stratosphere. For example, UV light
breaks up CFCs into molecules and atoms such as chlorine atoms that then
react and break down ozone into oxygen molecules and atoms. Such ozonedepleting processes cause more ozone depletion than ozone replenishment,
which leads to the thinning of the ozone layer (so-called 'ozone hole').
International conventions such as the Montreal Protocol restricting the use of
destructive chemicals have led to the recovery of stratospheric ozone.
EXTRACT FROM THE EXPERTS
Michelle Blanckenberg, Communications Manager for the African Climate
and Development Initiative (ACDI) writes:
Africa is rapidly changing and increases in populations’
dependent on natural resources suggests that achieving the
Sustainable Development Goals (SDG), as set out by the United
Nations, is a challenge for the continent. Climate change adds
to this development challenge. Much of the continent is arid,
semi-arid and sub-humid, with associated climate risks relating
to temperature and rainfall variability and stress. Vulnerability to
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these risks is high in many instances, because of development
deficits. Climate change is expected in many cases to
exacerbate these vulnerabilities, potentially slowing or reversing
development advances. Therefore development that is well
adapted to current and emerging climate risks is fundamental to
broader socio-economic development outcomes.
The importance of climate change for development is
reflected in Sustainable Development Goal 13, to “take
urgent action to combat climate change and its impacts”,
but the multidimensional nature of climate change is also
reflected in the way it intersects with many other SDGs, such
as SDG 2 (zero hunger), SDG 3 (good health and well-being),
SDG 6 (clean water and sanitation), SDG 7 (affordable and
clean energy) and SDG 11 (sustainable cities and communities).
The African Climate and Development Initiative (ACDI) was
therefore established as part of the University of Cape Town’s
(UCT) proactive response to this climate change and
development challenge and aims “facilitate and substantially
extend climate change research and education at UCT with the
specific context of addressing the development challenges of
Africa from an African perspective”. ACDI’s research further
aims to increase the scientific knowledge and understanding
needed to improve human development outcomes in the face of
climate change.
8.4.5 What is climate change and its effects?
Study chapter 10.4 in Fisher (2018) and chapters 6.2 and 6.3 in Zehnder et al.
(2018).
Summary
 Earth's temperature (warming and
cooling) depends on the balance
between energy entering and leaving
the planet (incoming and outgoing
radiation). Both natural and human
factors cause changes in Earth's
energy balance.
 Scientists have determined that Earth's climate is changing by studying ice
cores, tree rings, glacier ice, pollen counts and ocean sediments. This historical
record shows that climate varies naturally over a wide range of time scales.
Before the Industrial Revolution in the 1700s, changes were mostly influenced
by natural processes such as volcanic eruptions, natural changes in
greenhouse gas (GHG) concentrations, changes in Earth's orbit, and so forth.
However, recent changes in climate cannot be explained by natural causes
alone and is contributed to by human activities, especially the combustion of
fossil fuels.
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The greenhouse effect is the process whereby Earth's temperature increases
as GHGs acts as a blanket and absorbs reflected radiation from Earth's surface
and radiation from Earth itself and re-radiate it back to Earth. People's activities
influence natural carbon cycles and introduce copious amounts of GHGs into
the atmosphere, slowly increasing our temperatures worldwide and in some
instances leading to catastrophic impacts. Notable GHGs include water vapour,
carbon dioxide and methane.
GHGs differ in their sources, their residence time in the atmosphere, and their
ability to produce the greenhouse effect. This is measured by global warming
potential (GWP), which is the ability to absorb energy, as well as its lifetime in
the atmosphere.
Global warming refers to the recent and ongoing rise in global average
temperature near Earth's surface and represents only one aspect of climate
change.
Climate change is the significant change in the measures of climate lasting for
an extended period. The Intergovernmental Panel on Climate Change (IPCC)
is charged with evaluating and synthesising the scientific evidence surrounding
global climate change.
Scientists gather data to make meaningful conclusions and predictions
regarding climate change in the form of scientific models that undergo rigorous
peer-review processes.
In addition to global warming, the effects of climate change include higher
incidents of extreme weather such as droughts and floods, changed patterns
and amounts of precipitation, reduced ice and snow cover, increased acidity of
oceans, sea-level rise owing to the melting of ice caps in Greenland, the Arctic
and Antarctica, increased risk for spread of disease, to list a few.
These changes will impact our food supply, water resources, infrastructure,
ecosystems and our own health.
THE KNYSNA WILDFIRE DISASTER
Instructions
 Watch the video: https://www.youtube.com/watch?v=pqiEPJPiqEA (5:05
minutes)
Purpose
 The video "Knysna Fires Incident – An Introduction 2020" explains the 2017
Knysna wildfires that lead to widespread devastation. This video will help you
to understand the risks of greater droughts and other impacts from climaterelated changes to which nations of the Global South (including South Africa),
are especially vulnerable.
8.4.6 How do we slow down and adapt to climate change?
Study chapter 10.4 in Fisher (2018) and chapter 6.4 in Zehnder et al. (2018).
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Summary
 Two approaches to dealing with climate change include mitigation and
adaptation.
 Slowing down (mitigating) climate change involves reducing the number of
greenhouse gases in the atmosphere or preventing additional emissions.
Mitigating activities include the introduction of carbon taxes, regulations to
reduce GHG emissions, the change from internal combustion engines in
vehicles to electric motors (such as Tesla's ECQ vehicles from Mercedes-Benz
and ID vehicles from Volkswagen), alternative sources of electricity such as
wind and solar, and carbon sequestration methodologies.
 Adaptation involves making changes to our behaviour in response to the
changing environment. Adaptations may vary greatly from region to region.
Some of the adaptations include climate-smart agriculture that includes the
introduction of indigenous cattle that are adapted to locally available vegetation
such as the Nguni cattle and waterwise crops. Other adaptations are sourcing
freshwater through desalination from the oceans and the recycling of
wastewater for human consumption, the relocation of people from low lying
areas that will be affected by sea-level rises, the construction of dykes to keep
the seawater out and rehabilitated, and the conservation of wetlands that
protect against flooding. (Click here to read an article on desalination plants in
Cape Town.)
 You can take actions at home, while travelling, and at your place of work or
study to reduce GHG emissions and associated climate change risks. You can,
for example, choose to walk or cycle as opposed to taking a private vehicle,
and you can use energy more efficiently and use renewable energy sources.
8.5 CAPSTONE ACTIVITY
LEARNING UNIT 8: CAPSTONE ACTIVITY
Instructions
 Go to the Discussions tool on the GGH1503 module site.
 Go to the topic entitled Learning Unit 8: Capstone Activity.
 Reply by providing your response on the tasks detailed below.
Purpose
To enable you to apply the knowledge you have acquired on geographic tools,
maps, and GIS throughout the different learning units, by creating a map showing
the modelled temperature increase for parts of South Africa, Lesotho, Botswana,
Zimbabwe and Mozambique for 2050 based on the intermediary trajectory scenario.
It will help to write up a small report, based on the map, on the increase of the
temperature in general and on selected cities and towns.
Task instructions
For this activity, you will need QGIS and spatial data showing the level of
temperature increase for 2050 from the 2015 base temperature, major routes and
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railways, countries and provinces, and cities and towns. You need to revisit learning
unit 2's Introducing Geographic Tools and Maps, which discusses the required map
elements when creating a map. Use learning unit 6 as a guide on how to import
vector layers into QGIS. Download the step-by-step instructions for this activity on
the module site (Learning Unit 8 Capstone Activity.pdf). You can download the guide
and the GIS data from Google Drive:
https://drive.google.com/drive/folders/1iD7tD11KzktnChfh__0leed2YOc9oqoF
Task
1. Draw a map in QGIS as per instruction showing the temperature change,
countries, provinces, towns and cities and infrastructure.
2. Use a colour ramp showing the magnitude of change.
3. Briefly discuss the magnitude of change for the parts of the affected
countries.
4. Briefly discuss the selected cities and towns being affected by the
temperature increase and based on the module content speculate on the
impact of the rise in temperature.
5. Add your map and answers in a single PDF to the discussion blog for
comments by your fellow students and the lecturer.
Acknowledgements
The temperature change based on the worst-case climate change for 2050 has
been sourced from the CSIR's Natural Resources and the Environment (NRE)
Also visit https://pta-gis-2web1.csir.co.za/portal/apps/GBCascade/index.html?appid=b161b2f892194ed5938
374fe2192e537 for more information about climate change in South Africa.
You can download the PDF file from:
https://www.csir.co.za/sites/default/files/Documents/CSIR%20Global%20Change%
20eBOOK.pdf.
8.6 SELF-TEST
The following questions are intended to test your knowledge of some of the key themes
covered in this learning unit. You can use these questions as a self-assessment
exercise. This is not graded and does not contribute to your semester or year mark.
The feedback to these questions will be provided on myUnisa. You should attempt to
complete these questions before consulting the feedback.
8.6.1 List the top four gases that exist in the highest quantities in the atmosphere.
8.6.2 Discuss why the atmosphere is divided into layers.
8.6.3 What is the difference between indoor and outdoor air pollution?
8.6.4 What is the main cause of recent changes in Earth's climate?
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8.6.5 List the mitigation strategies that can be followed to reduce or slow down
climate change.
INDIGENOUS KNOWLEDGE SYSTEMS AND ITS KEY ROLE
IN UNDERSTANDING OUR LIVING EARTH
How can Indigenous knowledge help understand and address climate
change?
Watch the following videos:

https://www.youtube.com/watch?v=z3d_UsYgt1c (13:00 minutes)

https://youtu.be/rnbECHh-EVo (5:20 minutes)
8.7 CONCLUSION
Upon completion of this learning unit, you should understand what atmospheric
pollution is, the sources thereof and its impact. You investigated the various layers of
the atmosphere, the role of ozone, and what climate change means for our living Earth.
You looked at the causes and effects of climate change and the different ways in which
it can be addressed. You did an activity where you created a map, using GIS, showing
the increase in temperature over a part of SADC for 2050 and its possible impact.
Consider the changes you can make in your personal lifestyle and behaviours to live
more sustainably and help contribute to the fight against the most pressing
environmental challenges of our time. Now that you have reached the end of learning
unit 8, you have successfully completed all the learning units for the module.
8.8 REFERENCES
Beer, C.T. 2014. Climate Justice, the Global South, and Policy Preferences of
Kenyan Environmental NGOs. The Global South, 8(2): 84-100.
Fisher, M.R., (Editor). 2018. Environmental Biology. Open Oregon Educational
Resources. Available at: https://openoregon.pressbooks.pub/envirobiology/.
Miller, G.T. & Spoolman, S.E., 2018. Living in the Environment (19th Edition). Boston:
Cengage Learning.
Müller, C., Waha, K., Bondeau, A. & Heinke, J. 2014. Hotspots of climate change
impacts in sub-Saharan Africa and implications for adaptation and development.
Global Change Biology, 20: 2505-2517.
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Theodore, L. 2008. Air Pollution Control Equipment Calculations. New Jersey: John
Wiley & Sons.
Zehnder, C., Manoylov, K., Mutiti, S., Mutiti, C., VandeVoort, A. & Bennett, D. 2018.
Introduction to Environmental Science (3rd Edition). Biological Sciences Open
Textbooks. 4. Available at:
https://oer.galileo.usg.edu/cgi/viewcontent.cgi?filename=12&article=1003&context=bi
ology-textbooks&type=additional or https://alg.manifoldapp.org/projects/introductionto-environmental-science.
Ziervogel, G., New, M., Archer van Garderen, M., Midgley, G., Taylor, A., Hamann,
R., Stuart-Hill, S., Myers, J. & Warburton, M. 2014. Climate change impacts and
adaptation in South Africa. WIREs Climate Change, 5: 605-620.
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