2. CONTENT OUTLINE
1. Course Learning outcome
2. Introduction to Ecology
3. Fundamentals
4. Environmental cycles
5. Energy flow in ecosystem
6. Carrying Capacity of an Ecosystem
7. Influence of Human activity on
Environment
8. Introduction to Sustainable
Development and Sustainability
9. How to Help?
3. Why learn ecology
● This foundation course intends to develop an
understanding about the concept of Ecology,
Environment and Ecosystem to develop critical thinking
and sensibility towards nature, while vouching for
holistic and sustainable development.
● The theory of Ecology course is focused on the
interaction of organisms with each other and the natural
and built environment. This subject integrates biological,
chemical and physical sciences to understand our
changing environment.
4. Course Learning outcome
We can expect the following learning outcome:
● Understand Ecosystem and prevailing environmental issues
● Sensitize students about environmental management and
sustainable development
● Learn Key aspects of Sustainability and Sustainable Development
Goals (SDGs)
● Get an idea of Urban Landscape and Urban Environment in Dhaka
● Explore the concept of Ecology and Urbanism, Urban ecology
● Develop an understanding of Sustainable development and its
implication
● Able to integrate ecological considerations in projects, as well
understand consequences of different choices and to evaluate
alternatives
6. Definition of Ecology
Ecology - The biology of interactions
Ecology is the study of organisms and how they interact
with the environment around them.
Ecology = from the Greek root OIKOS, “at home”, and OLOGY,
“the study of”
“Ecology’ is the science which investigates organisms in
relation to their environment and a philosophy in which the
world of life is interpreted in terms of natural processes. It is
a branch of biology that studies the relationship between
organisms, their environment, and their associated energy
flows.
12. Understanding different terms
Organism
It is the lowest level of organization, which includes both
unicellular and multicellular organisms. All the living species
in this level exhibit all the characteristics required for the
existence of life.
Population
A population is a group of individuals of a single species
living together within a particular geographic area. They
interbreed and compete with each other for resources.
Community
It refers to the several populations that interact and inhabit
a common environment and are interdependent.
13. Ecosystem
Ecosystem, the complex of living organisms, their physical
environment, and all their interrelationships in a particular
unit of space.
Ecosystems contain biotic or living, parts, as well as abiotic
factors, or nonliving parts.
An ecosystem is a geographic area where biotic and
abiotic components specific to that space or community
work together to form a bubble of life.
The term ‘ecosystem’ is a sub-part of ‘ecology.’ Just like a
banana is a sub-part of fruit.
14. Biotic and Abiotic Factors
The biotic factor includes all living things, such as
microorganisms, plants, and animals.
The abiotic factor includes everything in the environment
that does not live. Water and soil, for example, are abiotic,
i.e., they have no life.
16. Biosphere
The Biosphere is made up of the parts of Earth where life
exists—all ecosystems. The biosphere extends from the
deepest root systems of trees, to the dark environments of
ocean trenches, to lush rain forests, high mountaintops, and
transition zones like this one, where ocean and terrestrial
ecosystems meet.
The biosphere is related to the atmosphere (gaseous air),
the hydrosphere (water), the lithosphere (crust/mantle),
which are all spheres of the physical world.
17. Environment
Environment etymologically means - ‘surroundings’,
is considered as a composite term for the conditions in
which organisms live and, thus, consists of air, water, food
and sunlight which are the basic needs of all living beings
and plant life, to carry on their life functions. In other words,
the environment consists of both biotic and abiotic
substances. Environment creates favorable conditions for
the existence and development of living organisms.
Environment is a very broad concept. Everything that
affects an organism during its life time is collectively
called its environment
18. Biodiversity
Biodiversity (from “biological diversity”) refers to the variety
of life on Earth at all its levels, from genes to ecosystems,
and can encompass the evolutionary, ecological, and
cultural processes that sustain life.
Biodiversity is a term used to describe the enormous
variety of life on Earth. It can be used more specifically to
refer to all of the species in one region or ecosystem.
19. Understanding different terms
Environment vs. Ecology
Environment refers to the interaction between the physical, chemical
and biological components. Ecology is the study of the relationship
between organisms and their environment.
Environment vs. Ecosystem
Environment refers to the surroundings, whereas, ecosystem is the
interaction between the environment and the living organisms.
Environment is the area where living organisms live. Ecosystem is the
community where the biotic and abiotic elements interact with each
other.
Biosphere vs. Ecosystem
An ecosystem is a specific individual environment where life evolves
and thrives. The biosphere is the total sum of all the ecosystems that
exist on our planet. The ecosystem involves the combination and
interactions of all the components of the biosphere.
20. Ecological indicators
People who study ecology often focus on specific
organisms to determine an environment’s health. For
example, the presence of lichens may suggest air pollution.
In this context, lichens are ecological indicators, i.e., they
give us information about our ecosystem.
22. Habitat
A habitat is the place where an organism lives
In ecology Habitat means either the area and resources
used by a particular species (the habitat of a species) or an
assemblage of animals and plants together with their
abiotic environment.
23. Types of Ecology
Global ecology: Studies the interactions between the different earth’s
ecosystems such as land, atmosphere, and water.
Landscape ecology: The study of patterns and interactions between
populations living in more than one ecosystem.
Ecosystem ecology: Ecosystem ecology studies the interrelationship
among biotic and abiotic factors of an ecosystem.
Community ecology: Studies organisms on a community level.
Population ecology: Study of different organisms living as a
population.
Organismal ecology: Deals with the study of interactions between
organism and their environment.
Molecular ecology: Study of organisms and abiotic factors on a
molecular level.
24. Goal of Ecology
The goal of ecology is
● To understand the relationships between organisms and
their environment,
● To use these relationships to help address various
complex and challenging environmental problems
25. Importance of Ecology
Conservation of Environment
Ecology helps us to understand how our actions affect the
environment. Thus, the study of the environment and organisms helps
us to protect them from any damage and danger.
Resource Allocation
With the knowledge of ecology, we are able to know which resources
are necessary for the survival of different organisms.
Energy Conservation
All organisms require energy for their growth and development. Lack
of ecological understanding leads to the over-exploitation of energy
resources such as light, nutrition and radiation, leading to its
depletion.
Harmonious living
Ecology encourages harmonious living within the species and the
adoption of a lifestyle that protects the ecology of life.
28. Environmental Cycles
A natural process in which elements are continuously
cycled in various forms between different compartments of
the environment (e.g., air, water, soil, organisms).
1. Carbon Cycle
2. Nitrogen cycle
3. Photsphorus cycle
4. Water cycle
29. Carbon Cycle
(Collected)
● Carbon is taken out
of the atmosphere
by photosynthesis
● It is passed on to
animals and
decomposers by
feeding
● It is returned by
respiration; in
plants, in animals
and in
decomposing
microorganisms
● In addition, it is
returned (in
increasing
amounts) by
combustion of
fossil fuels
30. Nitrogen Cycle
(Collected)
The 5 Major steps
involved in nitrogen cycle
1. Nitrogen fixation.
2. Nitrification.
3. Nitrate
assimilation.
4. Ammonification.
5. Denitrification and
Anammox.
31. Water Cycle
(Collected)
The 5 Major steps
involved in nitrogen cycle
1. Evaporation,
2. Condensation, and
3. Precipitation
34. Food Chains and Food web
Food chain refers to the order of events in an ecosystem,
where one living organism eats another organism, and later
that organism is consumed by another larger organism.
The flow of nutrients and energy from one organism to
another at different trophic levels forms a food chain.
● A food chain shows the transfer of energy from one
organism to the next
● The source of all energy in a food chain is light energy
from the sun
Food Web
In any ecosystem there are many food chains and,
generally, most plants and animals are part of several
chains. When you draw all the chains together you end up
with a food web.
35. Links of Food Chains
1. Producer/autotrophs: Produces energy through
photosynthesis. Plants are producers.
2. Consumers/Heterotroph: Depends on autotrophs
(producers) or other consumers for food, nutrition, and
energy.
● Primary consumers/herbivores): plant eaters (e.g. a cow).
● Secondary consumers/carnivores: meat eaters (e.g. a lion) and
omnivores.
● Tertiary consumers/omnivores: plant and animal eaters (e.g.
humans or birds)
1. Decomposers: Decomposers eat decaying matter
(microscopic organisms, including protozoa and
bacteria)
37. Food chain vs Food web
(Collected)
Difference Between Food Chain And Food Web
Food Chain Food Web
A linear pathway showing the flow of energy A multitude of networks showing the flow of energy
An organism of higher level trophic feeds on a
specific organism of lower trophic level
An organism of a higher trophic level has access to
more members of a lower trophic level.
Does not affect the adaptability and
competitiveness of organisms.
It has a role in improving the adaptability and
competitiveness of an organism.
38. Food Pyramid
Also known as Ecological pyramid, trophic pyramid,
Eltonian pyramid, Energy pyramid
The food pyramid is an ecological hierarchy of food
interactions in which the apex predator is at the top, each
level preys on the next lower level, and the bottom level is
generally green vegetation. Energy is transferred from one
trophic level to another in the ecosystem and loses some
amount at each trophic level.
Pyramids of energy illustrate the amount of energy
contained within the biomass of individuals within
different trophic levels.
41. Carrying Capacity of an Ecosystem
The carrying capacity of a biological species in a particular
habitat refers to the maximum number of individuals (of
that species) that the environment can carry and sustain,
considering its geography or physical features.
In ecology, carrying capacity is measured as the
maximum load of an environment.
42. Carrying Capacity Example
For example consider Tree population in a forest.
● Let’s say a forest can have a carrying capacity of about
a hundred trees.
● This means that the trees can grow without fiercely
competing for sunlight, nutrients, and space.
● This also implicates that the new sprouts may not be
able to thrive in the same manner because the tall and
older trees will cast a shadow over them, making
sunlight hard to access from down below.
43. How Humans Change Carrying
Capacity Factors
Humans create sub-populations with different needs according to
lifestyle, eventually impacting the carrying capacity of certain
ecosystem
For example, agriculture and husbandry helped expand the food
supply. However, certain modern technology and anthropogenic
activities cause critical damage to the population of other species.
forests and terrestrial habitats were cleared to build houses and
establishments.
Pesticides intended for killing off pests from crops leached nutrients
off the soil during rain and irrigation.
Bodies of water became polluted because of improper waste
disposal.
Nature has many factors that limit population growth. Thus, despite
technological advancement to limit resource competition, the
human population has to deal with other variables. Examples of
such variables are sanitation, diseases, outbreaks, and medical
care.
