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Human Ecology, By Dechasa Adare Mengistu,Haramaya University

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Human Ecology
By: Dechasa Adare (MSc.)
Haramaya University
2023 Ac. year
Dechasa.A
dechasaadare@gmail.com
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We are part of the environment along with all of Earth’s other organisms.
Organization levels of biology
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Definition terms
• Ecosystem: any geographic area
that includes all of the organisms
and nonliving parts of their physical
environment
• Biodiversity: Biological diversity is
refers to the variety of life forms at
all levels of organization
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Cont…
• Biomes: a large, relatively distinct
terrestrial region characterized by a
similar climate, soil, plants, and
Example: rainforest,
grassland, desert
animals regardless of where it occurs
on earth
• Ecosphere: The interrelation among
and between living organisms and the
atmosphere, lithosphere and
hydrosphere that they occupy.
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Cont…
Community—all the organisms
living in a certain area.
Example: pond community
Population—all the organisms
of the same species living in the
same area.
Example: frogs in a pond
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Cont…
• Habitat—place where an organism lives. It provides
food, water, shelter, and a place to reproduce.
• Example: a woodpecker’s habitat is the trees in a forest.
• Niche—everything an organism does and everything
it needs in its habitat.
• It is often defined as an organism’s job or role in its
community.
• Example: a woodpecker’s niche is catching and eating
insects.
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Cont…
• Limiting factor: An environmental factor that restricts the growth,
distribution, or abundance on a particular population
• Amount of water, food, and temperature
• Tolerance: Decreased response to a specific factor in the environment
over time
• Ecological Succession: The process by which organisms occupy a site and
gradually change environmental conditions so that other species can
replace the original inhabitants.
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Definition, Scope and Relationship with other sciences
• Ecology: branch of science that deals with interaction
between living organisms with each other and their
surroundings
• Ecology is a multi-disciplinary science, drawing on many
other branches of science
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Cont…
• Ecological footprint: The amount of biologically productive land and
water needed to indefinitely supply the people in a given area with
renewable resources
• Per capita ecological footprint: Average ecological footprint of an
individual in a given area
• Ecological deficit: Total ecological footprint greater than biological
capacity for resource renewal and absorption of wastes and pollution
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Cont…
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Scope of Ecology
• Ecology can be studied at several levels:
• From proteins and nucleic acids (in biochemistry and molecular
biology)
• Cells (in cellular biology)
• Organisms (in botany, zoology, and other similar disciplines)
• At the level of populations, communities, and ecosystems
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Cont…
Organismal ecology
Population ecology
Community ecology
The focus of ecological
studies occurs at many
different scales.
Ecosystem ecology
Landscape ecology
Global ecology
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Disciplines of ecology
• Ecology is a broad science which can be subdivided into major and minor sub
discipline.
• The major sub-disciplines include:
• Behavioral ecology, studies the ecological and evolutionary basis for animal
behavior, and the roles of behavior in enabling animals to adapt to their
ecological niches
• Population ecology, deals with the dynamics of populations within species, and
the interactions of these populations with environmental factors
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Cont…
• Community ecology: studies the interactions between species within an
ecological community;
• Ecosystem ecology: studies the flows of energy and matter through
ecosystems;
• Global ecology: looks at ecological questions at the global level: macro
ecological questions
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Broadly, ecology is divided into following categories
• Physiological ecology: Study about the response of single species to environmental
factors
• Population ecology: focusing on the abundance and distribution of individual
species and the factors that cause such distribution;
• Community ecology,: number of species found at given location and their
interactions
• Ecosystems ecology: structure and function of the entire suite of microbes, plants,
and animals, and their abiotic environment, and how the parts interact to generate
the whole.
• i.e: energy and nutrient flows of ecosystems.
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Importance of Ecology
• Human economies are based on the exploitation and management of
nature
• Study of population dynamics (demography) of our own species, the
food and fossil energy flowing through our society
• All of us live in a natural or partly natural ecosystem
• Humans appear to be changing aspects of the global environment in
many ways
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Ecology: Factors Sustaining Life
1) Gravity
2) Flow of Energy
Producers
Consumers
Trophic Levels
3) Cycling of Matter and Nutrients
• Carbon, Nitrogen, Water, Phosphorus, (Sulfur) Cycles
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Gravity
• Atmosphere and life on earth
Energy Sources
• All living things obtain and use energy
and materials
Energy source for the natural
world =
Sun or Solar Energy
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Various ways to obtain, acquire energy
• Autotrophs: an organisms capture energy from sunlight or chemicals and
convert it into forms useable to living cells =
• Called Primary Producers
• By photosynthesis (light) or Chemosynthesis (chemicals)
• Use solar energy
EX: Algae, plants, and some
Microorganisms
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Cont…
• Deep-sea ecosystems depend on primary producers that use
chemical energy from inorganic molecules such as hydrogen
sulfide.
• Chemosynthesis: is the use of
chemical energy to produce
carbohydrates
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Cont…
• Heterotrophs = Organisms that must acquire energy from other
organisms
Cannot make their own food
Must eat/ingest to get their energy
Called consumers
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Types of Consumers: Diet
• Consumers are classified by the ways in which they acquire energy and
nutrients
1. Carnivores kill and eat other animals, and include snakes, birds of
prey, lions, etc.
2. Scavengers= animals that consume the carcasses of other animals
that have been killed by predators or have died of other causes
3. Herbivores = obtain energy and nutrients by eating plant leaves,
roots, seeds, or fruits
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Cont…
• Omnivores: animals whose diets naturally include a variety of
different foods that usually include both plants and animals
• Decomposers =feed by chemically breaking down organic matter
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Energy Flow
What happens to energy stored in body tissues when one organism
eats another?
How does energy flow through ecosystems?
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Cont…
• Energy moves from the “eaten” to the “eater.”
A food chain = a series of steps in which organisms transfer
energy by eating and being eaten.
• Food chains can vary in length.
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Cont…
• Food Webs:
• Feeding relationships much more
complicated than a chain
• Each path through a food web is a
food chain.
• Links all of the food chains in an
ecosystem together
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Trophic Levels
• Each step in a food chain or food web = a trophic level
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Trophic level Pyramid
About 10% of
available
is passed up
10
Tertiary
Consumer
The rest is lost as
Heat and Waste
Secondary
Consumer
100
1000
Primary Consumer
Heterotrophs
Herbivores
Producers
Autotrophs
Uses the sun’s energy to make its own food- photosynthesis
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Ecological pyramids
• Ecological pyramids show the relative
amount of energy or matter contained
within each trophic level in a given food
chain or food web.
• There are 3 different types of ecological
pyramids:
•
Pyramids of energy
•
Pyramids of biomass
•
Pyramids of numbers
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Cont…
2. Biomass Pyramid:
• Represents the amount of living
organic matter at each trophic level.
• Largest biomass is at the base of the
pyramid.
• Pyramid of biomass records the
total
dry
organic
matter
of
organisms at each trophic level in a
given area of an ecosystem
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Cont…
3. Pyramid of Numbers:
Shows the relative number of
individual organisms at each
trophic level.
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Ecosystem Goods and Services
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i
Humans, Biodiversity and Ecosystems
Development impacts ecosystem services
Ecosystem services sustain development
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What are ecosystem services?
• Benefits derived from ecosystems
• Products of ecosystem processes
• Strong positive link between ecosystem processes and
biodiversity
• Loss of biodiversity strongly linked to reduced ecosystem
services
• Threat to human well-being
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Cont…
Ecosystem goods and services represent the
benefits that humans derive from naturally
functioning ecological systems
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• Types of Ecosystem Services
1. Regulating services – purification of air and water,
• detoxification and decomposition of wastes, climate regulation, erosion
control etc.
2. Provisioning services – provision of food, fuel, fiber, and freshwater
3. Supporting services – formation and preservation of soils, protection
from ultraviolet rays, pollination of natural vegetation etc.
4. Cultural services – spiritual, esthetic, recreational
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Cont…
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Cont…
Joint products of ecosystems
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Implications
• The degradation of ecosystem services could grow
significantly worse during the first half of this century
and is a barrier to achieving the Millennium
Development Goals
• Reversing ecosystem degradation while meeting
increasing demands for their services will involve
significant
changes
in
policies,
practices,
and
institutions
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Why ecosystem accounts?
• Information for tracking changes in ecosystems, such as degradation
• Information for linking those changes to human activities and human
well-being
• Extends the scope of our information for analysis of impacts on the
environment (and, thus, ultimately, on societies)
• Information on ecosystem services and the trade-offs/co-benefits
involved
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Ecosystem Services as Flows From Ecosystem Assets
Individual & societal well-being
Benefits
Ecosystem services
Human inputs (e.g. labour,
produced assets)
Ecosystem processes
Ecosystem characteristics
Intra-ecosystem flows
Inter-ecosystem flows
ECOSYSTEM ASSET
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Ecosystem goods and services Systemic Model
Secure
environmental
vision and
governance
Assess & Value
Ecosystem
Goods &
Services
Decentralized
plans
Monitor
results,
develop and
share
knowledge
Spatial
plans
Innovative
Finance
Mechanism
s
Medium
Environmen
Term
tal Fiscal
Expenditure
Reform
Framework
Sector
Plans
Integrated
EGS benefits feed into
Sustainable Development &
Poverty Reduction Strategies
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Demystifying
“environmental
jargon”
EGS in
Development/
Poverty/
Disasters
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Common Look at Biodiversity and Ecosystems
Common Understanding
Real Situation



Wrong



Correct
• Human beings are part of biodiversity - they interact directly with
all its elements at different geographical and temporal scales.
• Ecosystems provide vital services for human needs and
development. They are found in a state of dynamic equilibrium, to
which development can cause severe damages.
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Ecosystem Based Solutions vs Manmade Solutions
Ecosystem Based Solutions
Man-Made Solutions
-Cheaper than man-made
-Costly and might involve
infrastructures (water treatment
recurring operational costs
plant…)
-Can alter the functions and
-Preserves the functions and services
services of ecosystems
of ecosystems
-Requires access to technology
-Ecosystem management skills
required
Mainly Pro-active Approach
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Mainly Responsive Approach
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Governance and Vision
Sound environmental vision and governance can favor sustainable results
Governance
Strengthen environmental
governance
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Environmental
Vision
Working with
nature
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Set Long Term Environmental Vision
Building an inclusive long term development vision of EGS
Green Constitutions
& Legal Initiatives
Constitutions which refer
Directly to environmental
rights
National
Priorities
Clear reference to
ecosystem/biodiversity
objectives in long term
development strategies
Global environ.
Policiescommitments
integrative of
Multilateral Environmental
Agreements
Limits of Economic Models
“Society must urgently replace its defective economic
compass so that:• It does not jeopardize human well-being and planetary
health
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Integrative and EGS Inclusive Planning
Decentralized
Plans
Spatial Plans
Plan in terms of spatial
layers
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Sectors Plans
Plan at lowest level
possible
Include green
considerations
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Greener Budgeting and Financial Planning
Budgeting and Financial planning need to be environmentally inclusive
Innovative
Financial
Mechanisms
Environmenta
l Fiscal
Reform
Environmental taxation/
Eliminating perverse subsidies
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New EGS based revenues
Medium Term
Expenditure
Framework
EGS based strategic budgeting
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Adaptive Management and Knowledge Consolidation
Data Collection
Monitoring and
Evaluation
Lessons Learned
and Knowledge
sharing
Continuously adjust
strategies and plans
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Develop new EGS
knowledge
Awareness and
Capacity
Building
Enhance awareness and
capacities
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Ecosystem-Based Management
Focuses on key ecosystem processes and their responses to
perturbations;
• Integrates ecological, social, and economic goals and recognizes
humans as key components of the ecosystem;
• Defines management based on ecological boundaries rather than
political ones
• Addresses the complexity of natural processes and social systems by
identifying and confronting uncertainty
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Cont…
• Uses adaptive management where policies are used as
experiments and are modified as information is gained;
• Engages multiple stakeholders in a collaborative process to
identify problems,
• Understand the mechanisms of driving factors
• Considers the interactions among ecosystems
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Cont…
Systems Ecology
• All ecosystems are open systems embedded in an environment
• Ecosystems have many levels of organization and operate
hierarchically
• Mass, including biomass, and energy are conserved
• The carbon based life on Earth has a characteristic basic
biochemistry which all organisms share
• No ecological entity exists in isolation but is connected to others.
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Cont…
• Ecosystem processes are irreversible (law of thermodynamics in
ecology).
• Biological processes use captured energy (input) to move further from
thermodynamic equilibrium
• After the capture of energy, ecosystem growth and development is
possible (physical structure or biomass, network, information)
• An ecosystem receiving solar radiation will attempt to maximize ecoexergy storage or maximize power
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Thank you
By: Dechasa Adare (MSc.)
Haramaya University
2023 Ac. year
dechasaadare@gmail.com
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