Environment
and
ecosystems
Environment
• The environment is the natural world, encompassing
the interaction of all living species, climate, weather and
natural resources that affect human survival and
economic activity.
• The environment refers to everything that surrounds us,
including the place where we live. We usually use the
term ’environment’ to refer to the physical aspects of
our surroundings, which may be living (biotic) or nonliving (abiotic).
• This means that if you live in a city, the environment
consists of the buildings, roads and other infrastructure,
while if you live on a farm, your environment consists of
you pastures, farm house etc.
Environment
• Although an environment consists of non-living and living
things, the term ’environment’ really just describes one’s
surroundings, but does not really define the
relationships, or dynamic nature of those surroundings.
• To study how the living and non-living parts of the
environment depend on and are influenced on each
other, we need to understand a different concept- the
ecosystem.
• Ecology is the study of all the interactions within
ecosystems
Human
impact on
the
environment
Negative:
• Pollution
• Deforestation
• Habitat destruction
Positive:
• Conservation
• Management of resources
• Reuse and recycle
• An ecosystem is any well-defined
area in which there is a close
interaction between the plants,
animals and their environment.
• Some examples of ecosystems are a
river, a grassland or even a fallen
rock.
Biotic vs
abiotic
factors
• Biotic factors are living organisms such as plants,
animals, microorganisms etc.
• Abiotic factors are non-living factors such as soil,
water, temperature and sunlight.
• Biotic and abiotic factors interact amongst
themselves and with each other in a way that helps
to balance the energy flow of the ecosystem
Complete the remote learning
worksheet: week 3
Abiotic factors
• Factors that are the physical
geography of an area , including
PHYSIOGRAPHIC
FACTORS
• aspect ,
• slope and
• altitude
Aspect
• The direction in which an area faces in relation to the direction
of the sun.
• In South Africa, the sun shines from the north.
• This means that north-facing slopes are exposed to the direct
rays of the sun for longer periods than south-facing slopes.
• North-facing slopes will be hotter and drier.
• South-facing slopes will be moist and cooler and will have
lusher vegetation.
Slope
• The slope of the land is how steep or
gentle the gradient of a surface is.
• Water flows faster on steep slopes,
which means that more erosion takes
place.
• The soil on steep slopes tends to be
thin and infertile, and can only support
smaller plants.
• There is less erosion on more gradual
slopes
Altitude
• Altitude is the height above
sea level.
• At higher altitudes, there is
a decrease in atmospheric
pressure, oxygen content
and temperature.
• Rainfall and wind speeds
are greater and frost and
snow occur
2/8/2024
13
Edaphic factors
• All the soil-related factors that
influence the growth and
development of plants in a
particular environment
• Soil is important for plant growth
as it provides water and
minerals, and holds plants firmly
in the ground.
• The type of soil in an area will
determine the kinds of plants
that will grow there.
Edaphic factors (related
to SOIL)
Air content
Soil texture
Water
retention
Humus
content
Soil pH
2/8/2024
15
Characteristics
of soil
pH:
Soil pH is a measure of how acidic or
alkaline the water in the soil is.
Most plants grow best at a neutral ph.
Characteristics of soil
Humus content:
Humus is the organic component of soils
formed by the breakdown of dead pants
and animals in the soil by bacteria and
fungi.
These nutrients can be taken up by
plants
Humus separates the soil particles,
allowing air and water to enter. High
humus content = fertile soil.
Characteristics of soil
Texture: The texture of the soil
is determined by the size of the
soil particles
Clay soil
Loam soil
Sandy soil
2/8/2024
19
SOIL TYPES
CLAY SOIL
LOAM SOIL
SANDY SOIL
Texture
Result of the
size of the soil
particles
Tiny particles and
is soft, smooth
and sticky when
wet.
Contains a mixture of
sand- and clay-sized
particles which stick
together when moist.
Contains large and
loose particles and
feels coarse even
when wet.
Air content
Small spaces,
contain very little
air
Mixture of pore sizes
and contain the right
amount of air that
allows plants to thrive
Have big spaces or
pores between the
particles and
contain a lot of soil
air. (aerated)
SOIL TYPES
CLAY SOIL
LOAM SOIL
SANDY SOIL
Water
retention
capacity
(How much
water it can
hold)
Water drains
slowly out of
clay; water
retention high
Water retention is
moderate
Water rapidly
drains out –
water retention is
low.
Humus
content
Little
Plenty
Little
Climatic factors refer to the long-term patterns and conditions of the Earth's atmosphere
in a particular region
Climatic factors
Sunlight
• Plants grow only where
there is enough light for
photosynthesis.
• Some plants are adapted
to grow in full sun (sun
plants) and others prefer
less light and grow best
in the shade (shade
plants).
Climatic factors
Temperature
• Temperature is a measure of
how hot or cold an area is.
• The temperature changes
from the equator to the poles.
• This is due to the decrease in
temperature and rainfall
further away from the equator.
Climatic factors
Water
• Water makes up about 70% by
weight of most living things,
therefore, they cannot survive
without it.
• Many chemical reactions essential
for life occur in water.
• Water transports various dissolved
substances inside and between cells
and
• it maintains a stable body
temperature.
Wetlands
Wetlands: Is an area of land that is mostly
covered with water. Wetlands are
essential ecosystems because:
 They act as natural filters trapping
nutrients, soil, disease-causing bacteria
and pollutants.
 They slow down floodwaters, as they
act like a sponge and store water. This
reduces erosion and flood damage. It
also maintains a steady flow of water
during the year.
 Wetlands are rich in plant life and
provide food and shelter for many
organisms.
Climatic factors
Atmospheric gases
• Composition of the atmosphere:
• 78% Nitrogen,
• 21% Oxygen,
• 0,04% Carbon dioxide and
• some water vapour and other gases
• Oxygen is needed by plants and animals for
respiration.
• Carbon dioxide is needed for photosynthesis.
Climatic factors
• Atmospheric gases
• The atmosphere traps some of
the sun’s heat, preventing it from
escaping back into space.
• This is called the greenhouse
effect.
• Water vapor, carbon dioxide and
methane are the main
greenhouse gases.
Climatic factors
Atmospheric gases
• These greenhouse gases allow the sun’s energy
to pass through the atmosphere and warm the
Earth’s surface.
• The earth radiates some of the heat energy back
into space.
• Some of the heat energy is absorbed by the
greenhouse gases.
• This warms up the air to keep the atmosphere at
a temperature that allows life to exist.
Biotic factors
 The biotic components are the
plants and animals.
 It also includes organisms such as
the fungi and lichens as well as
the very small organisms like
bacteria.
 The bacteria are so small that it
can be seen only with a
microscope.
 Such organisms that are invisible
to the naked eye are called microorganisms.
 Some algae and fungi are also
examples of micro-organisms.
Producers
• These are biotic factors that can make their own
food.
• They are able to do this by absorbing energy from
the sun.
• The process by which they can manufacture their
own food by using the radiant energy is called
photosynthesis
• They are also called autotrophs (Autotrophic refers
to the mode of nutrition in which an organism can
produce its own food.)
• Form the first trophic level
• They have the greatest amount of energy
Consumers
Consumers are organisms within an ecosystem that obtain their energy and nutrients by consuming
other organisms
There are 3 categories of consumers.
• Carnivores: these are the organisms that feed on animal matter only.
• Herbivores: these are organisms that obtain their food from plant matter.
• Omnivores: these are organisms that feed on both plant and animal matter
Consumers
• Primary consumers: Herbivores, occupy
the 2nd trophic level
• Secondary consumers: Carnivores or
omnivores, occupy the 3rd trophic level
• Tertiary consumers: Carnivores or
Omnivores, occupy the 4th trophic level
Decomposers
 These are organisms that feed on dead organic
matter.
 They are usually micro-organisms .
 But some decomposers can be macroscopic e.g.
worms.
 As they break down the bodies of the dead organic
matter they release important substances back into
the environment.
 These substances then can be used by green
plants.
• Water, carbon dioxide, mineral salts and energy in
the form of heat are some of the substances that
are released by decomposers.
Complete remote learning
worksheet
(Week 4)
Energy flow in
ecosystems
• Nearly all of the energy in Earth's ecosystems
originates from the Sun.
• The energy is distributed in the ecosystem through the
food chains and food webs.
• Living organisms occur at different feeding levels in an
ecosystem (food chains or food webs). These feeding
levels are called trophic levels.
Food chain
A food chain is a linear representation of the flow of energy in an
ecosystem, showing the sequence of organisms involved in the transfer of
energy from one trophic level to another
2/8/2024
39
Food Web
An interconnected model that
represents the multiple feeding
relationships within an ecosystem. It
includes multiple food chains that
are interwoven and overlapping
2/8/2024
40
• The flow of energy in ecosystems is important to the life on earth
Ecological pyramid
It is a diagram that shows the relative amounts of
energy or matter contained within each trophic
level in a food chain or food web.
Types of ecological pyramids are
• energy pyramid: shows relative amounts of
energy available at different trophic levels
• biomass pyramid: shows the total mass of the
organisms at each trophic level.
• number pyramid: shows total number of
organisms at each trophic level
2/8/2024
43
2/8/2024
44
Pyramid of biomass
2/8/2024
45
Pyramid of numbers
a) Grassland community
b) Baobab tree community
Tertiary
consumer
Secondary consumer
Primary consumer
Secondary
consumer
Primary
consumer
Represent the number of organisms at each trophic
level.
2/8/2024
46
Complete
remote learning
worksheet
(week 5)
Nutrient Cycles
Water cycle
The water cycle
• Water is an inorganic compound with two hydrogen atoms and one oxygen
atom. It can exist in three phases in the environment, i.e. solid, liquid and
phase.
• The water-cycle plays an important role in moving water through the
organisms and in the environment. The water-cycle may be studied in two
broad steps:
• Firstly, the precipitation, distribution, and absorption.
• Secondly, evaporation and condensation.
• The water cycle shows the continuous movement of water within the Earth
and atmosphere. It is a complex system that includes many different
processes. Liquid water evaporates into water vapor, condenses to form
clouds, and precipitates back to earth in the form of rain and snow
The water cycle
Precipitation
Water moves from the atmosphere to the earth in the form of rain, mist, hail, dew and
snow.
Infiltration
Water infiltrates deep into the soil and comes to rest on solid rock formations to create the
water-table
Evaporation
Process of turning from liquid into vapor
Transpiration
Loss of water through the stomata of the leaves
Run-off
Some water from precipitation runs off into the rivers and streams, later into the dams,
lakes and the sea
OXYGEN CYCLE
The oxygen cycle
• Oxygen is essential for cellular respiration. It is
used in the breakdown of glucose to release
energy. Energy is required for growth and
metabolic activities in living organisms.
• The normal concentration of O2 in the
atmosphere is approximately 21%. Some of this
O2 dissolves in the waters of ponds, lakes, dams,
rivers and the oceans.
Oxygen
cycle
Respiration
• The chemical process whereby energyrich molecules, such as glucose, is
chemically broken down in the
presence of oxygen to release energy
Photosynthesis
• Process whereby plants absorb carbon
dioxide and in turn release oxygen in
the atmosphere as a by-product
Complete remote learning
worksheet (Week 6)
CARBON CYCLE
The carbon cycle involves the following
processes:
Photosynthesis:
• Carbon dioxide is absorbed by plants and turned into carbohydrates, proteins
and fats.
Feeding:
• Carbon passes from plants to animals during feeding, and is turned into
carbohydrates, proteins and fats in the animal’s body
Death and decay
• Carbon passes from plants and animals to decompose organisms and turn he
carbon into decomposer carbohydrates, proteins and fats
The carbon cycle involves the following
processes:
Respiration
• Carbon is released into the atmosphere in the form of carbon dioxide
Compaction:
• sometimes the dead plants and animals do not break down and the carbon
becomes locked in for long periods (for fossil fuel)
2/8/2024
62
Nitrogen cycle
Nitrogen (N2 ) makes up most of the gas in the atmosphere
(about 78%).
Nitrogen
cycle
Nitrogen is important to living organisms and is used in the
production of amino acids, proteins and nucleic acids
(DNA, RNA).
Nitrogen gas present in the air is not available to organisms
and thus has to be made available in a form absorbable by
plants and animals.
Only a few single-cell organisms, like bacteria can use
nitrogen from the atmosphere directly.
For plants, nitrogen must be changed into other forms, e.g.
nitrates or ammonia. This process is known as nitrogen
fixation.
Processes
involved in
the
nitrogen
cycle.
2/8/2024
Nitrogen fixation: nitrogen fixing bacteria and
lightning turn nitrogen gas in the atmosphere
into nitrate salts and ammonium salts in the soil
Fertilisation: farmers add nitrogen to the soil in
the form of fertilisers
Absorption: plants absorb nitrogen in the form
of nitrate salts from the soil and turn it into
plant proteins
Feeding: animals digest plant proteins and use
the nitrogen they contain to make animal
proteins
65
Processes
involved in
the
nitrogen
cycle.
2/8/2024
Death and decay: decomposers break down some of
the proteins in dead plant and animal matter and use
the nitrogen from these proteins to make
decomposer proteins
Ammonification: decomposers break down some of
the proteins in dead plant and animal matter and
release the nitrogen from these proteins into the soil
as ammonium salts
Nitrification: Ammonium salts in the soil are turned
into nitrites and then nitrate salts in the soil by
nitrifying bacteria
Denitrification: conversion of nitrates into gaseous
nitrogen
66
2/8/2024
68
Complete remote
learning worksheet
(week 7)