Learning Outcomes

At the end of this
Lecture, students will be able to

• Discuss different types of ecosystems

• Cite biological components of Ecosystems

• Explain energy flow in Ecosystems


• Ecosystem

• Different types of ecosystems

• Biological components of Ecosystems

• Functions of ecosystem

• Importance of ecosystem

• Energy flow in Ecosystems


The self-sustaining
structural and functional interaction between living and non-living components

Scientific study of the interactions between organisms and the environment

Types of


1. Terrestrial ecosystems (grasslands, forests, desert

2. Aquatic ecosystem

    a. Lentic
(Stagnant water) like lake, ponds etc.

    b. Lotic (Flowing
water) like river, ocean, sea, etc


1. A crop land, garden, aquarium, park, kitchen garden

of an Ecosystem

An ecosystem consists of two main components

Abiotic or Non-living

1. Inorganic substances

2. Organic compounds

3. Climatic factors

Biotic or Living

1. Autotrophs or Producers

2. Heterotrophs or Consumers

3. Decomposers or Saprotrophs


• Terrestrial ecosystems are ecosystems on land.

• They can be as big as a continent, or as small as an

• They make up about 28% of the entire World’s ecosystems.

What Animals Live

• Many different animals call terrestrial ecosystems home.

• The most common are:

– Birds

– Mammals of all shapes and sizes

– Insects

What Plants Live

• Many plants also call terrestrial ecosystems their home
also, we see many of them every day!

• Common plants are:

– Flowering plants, like roses

– Mosses, like moss that grows on rocks

– Conifers, which are pine trees

Examples of
Terrestrial Ecosystems

• Forests

• Deserts

• Grasslands


• There is something special about aquatic ecosystems.

• There is actually two different types of aquatic

• One type is freshwater

• The other type is saltwater.

• Both types, however, are ecosystems that are in the water.


• Freshwater ecosystems are places in the water where there
isn’t much salt in the water.

• These include places like lakes, rivers, and creeks.

What Animals Live in
Freshwater Ecosystems?

• A lot of animals live in freshwater ecosystems.

• Animals include:

– Freshwater fish, these fish can’t live in the ocean
because it is too salty for them, so they live in freshwater

– Amphibians, like frogs

– Reptiles, like water snakes

What plants live in
freshwater Ecosystem?

• Many plants call freshwater ecosystems their home, even if
we can see them from the surface of the water

• Some plants are:

– Cattails

– Grasses

– Trees


• Saltwater ecosystems are again in the water, but unlike freshwater
ecosystems, saltwater ecosystems have very salty water.

• They also make up the vast majority of the Earth’s

• They are the world’s largest ecosystems.

• Some examples of saltwater ecosystems are oceans and coral

What Plants are in
Saltwater Ecosystems?

• Seaweed is one of the most common types of plants that
live in saltwater ecosystems.

• Another plant that lives in the ocean is kelp.

What Animals Live in
Saltwater Ecosystems?

• There are so many animals that live in saltwater

• Animals that live in saltwater ecosystems include:

– Fish

– Sharks

– Jellyfish

– Whales

Function of

• Producers, the green plants, fix radiant energy (solar
energy) and with the help of minerals take from their edaphic (soil where they
grow) or aerial environment and build up complex organic matter. These are
their food. So, with the help of solar energy they convert the chemical energy
of the food to kinetic energy and finally heat energy

• The animals eat up plants and other animals as food. So,
the energy is transferred through food to animals

• When plants and animals die, then decomposers (like
certain bacteria and fungi) act on their dead bodies and decompose them into
simple materials like carbon dioxide, water and minerals which go back to air,
water bodies and soil from where they were taken

• The carbon dioxide from air, water and minerals from water
bodies and soil are again taken up by green plants along with solar energy to
make their food. This process is repeated again and again. This leads to
continuous functioning of the ecosystem


• Transfer of energy and matter takes place in the process
of predator and prey relationship in a food chain. The original source of energy
is the energy from the sun

• Out of the enormous amount of energy continuously radiated
by the sun, most of it is reflected or refracted back (by atmosphere, earth
surface and object like plants). Only a very small fraction, about one per
cent, of the solar energy received by the plant is used through the process of

of Ecosystem

• We know that no living organism can live in isolation. We
cannot survive without producers in nature. All living beings depend on other
living beings in the biological community. Not only they are dependent on one
another, but also each of them exist in a certain proportion. This creates a
complete balance in nature amongst living organisms.  This is evident from the study of food chains
which operate between living organisms

balance in nature

• The balance between the living beings and also with the
non- living environment is called the Ecological Balance or simply a Balance in

• Unfortunately, however human activities have upset the
ecological balance in nature, so it is more essential that balance in nature
should be established soon because it is essential for our own existence

of Ecosystem

• Forests are important components of our environment. Rapid
destruction of this important resource is a cause of concern

• Afforestation, preventing reckless cutting of trees and
making everyone aware of the need to conserve it will help forest conservation

• Nature enjoys ecological balance only if the relative
number of species is not disturbed. So, conservation of wildlife is important
for the future

• National parks, wildlife sanctuaries and biosphere
reserves are established to protect and conserve wildlife

• Such measures would ensure that the wildlife does not
become extinct

• Conservation of aquatic life would be ensured by removal
of industries near water bodies


Awareness about ecosystem conservation can be done by
posters, competitions about ecosystem conservation, arranging T.V. programmes
and websites related to ecosystems


• Limiting factors determines distributions

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