2. CONTENT
Introduction of ecosystem
Ecosystem Definition
Structure of ecosystem
Function of ecosystem
1.Productivity
2.Decomposition
3.Enegry flow
4.Nutrient cycling
Classification of ecosystem
Forest as an ecosystem
Grassland as an ecosystem
3. Introduction of Ecosystem
The term ‘Ecosystem’ was proposed by a British ecologist
A. G. tansley in the year 1953.
What is ecosystem ?
A community, along with its physical environment,
has a living (biotic) component and a non-living(a biotic)
component .
Ecosystem consists of two words:
Eco-Environment
Ecosystem
System-Interaction
4. Ecosystem:Definition
Acording to E.P. odum , an American
Ecologist, the ecosystem is the basic functional unit of
organism and their environment interacting with each
and with their one components.
e.g. Grassland, forest, Aqurium, Pond, Lake, River and
Ocean.
5. Structure of ecosystem :
A biotic – Eg. Soil, Water, light.
Ecosystem
Biotic – Eg. Producers and
consumers
6. Biotic
-Organic matter
-Living things
-Oysters
-Blue crabs
-Zooplankton
-Phytoplankton
-Jellyfish
A biotic
-Climate
-Nonliving things
-Sun light
-Temperature
-Nutrient enrichment
-Humidity
-Soil
7. Function of ecosystem :
The components of the ecosystem are seen to
function as a unit when we consider the following a
spects:
Productivity
Decomposition
Energy flow
Nutrient cycling.
Productivity: The productivity of an ecosystem is the rate
at which solar energy is fixed by the vegetation of the
ecosystem; it is further classified into primary productivity,
Secondary productivity and net productivity.
8. Decomposition:
The breakdown of complex organic matter
into inorganic substances like carbon dioxides, water
and nuterients and the process is called decomposition.
Steps in decomposition :
-Fragmentation
-Leaching
-Catabolism
-Humification
-Mineralization.
9. Energy flow :
The flow of energy is one way direction from
producer to consumers, and ends in decomposition
process.
-However, a part of the energy is lost as heat and
agrees with the phenomenon of second low of
Thermodynamic.
Nutrient cycle : A nutrient cycle (or ecological recycling)
is the movement and exchange of organic and inorganic
matter back into the production of living matter.
-The process is regulated by food web pathways that
decompose matter into mineral nutrients.
-Nutrient cycles occur within ecosystems.
10.
11.
12. Forest as an Ecosystem :
Forest ecosystem is the best example of a
terrestrial ecosystem .Like other ecosystem,there are two
main components of forest ecosystem:
A. A biotic component.
B. Biotic component.
A. A biotic component : In a forest ecosystem soil,
moisture, air and sunlight from the a biotic or physical
component.
B.Biotic component : There are three important
classes of biotic components: 1. Producers,
2.Consumers, 3.Decomposers and transformers.
13. 1. Producers:
All the green plants of a forest are producers. They are
the main sources of food for all the animals. There are several
layers of vegetation in the forest. The plants of top stratum
are angiospermous and gymnospermous trees. These plant
utilize radiant energy of sun to the greastest extent. Below
the level of trees there is layer of shrubs which consume light
energy of low intensity coming through trees. Just below the
shrubs there are gasses, herbs, lichens and mosses. These
also manufacture food. These plants get least light.
14. 2.Consumers :
There are a number of consumers in an old
dense forest. Consumers of first order in the forest are
grasshoppers, rabbit, deer, monkey, birds and many
other wild herbivorous animals which utilize plants
directly as their food. Secondary consumers are
wolves, pythons, jackals etc. Which consume the flesh
of herbivores. Lion, tiger, hawks are the consumers of
top level.
15. 3.Decompsers and transformers :
These are micro-organisms, chiefly bacteria and
fungi which attack dead bodies or producers and
consumers and convert complex organic compounds
into simpler inorganic compounds and elements.
These free elements again return to the a biotic
component and are re-utilised by producers in their
nutrition.
17. Grassland as an Ecosystem:
Grassland occupy about 19 pre cont of the
earth’s surface. The major grassland ecosystem of the
world are the great plains of Canada and United states,
S. Argentina to Brazil and S . Asia to Central Asia. The
various components of a grassland ecosystem are as
fellows:
A. A biotic Components:
The nutrients present in soil and the aerial
environment are the a biotic components (the
elements like C,H,O,N,P,S etc. are supplied by CO2,
Water, nitrates, Phosphates and sulpltates) .
18. B. Biotic Components:
These include mainly (a) grasses, like Dichanthium,
Cynodon , Desmodium, Digitaria, Dactyloctenium,
Setaria etc. as producers; (b) animals like Cow,
buffaloes, deers, sheep, mouse and many insects as
consumers, (c) Fungi like Mucor, Asperillus,
Penicillium, Cladosporium, Fusarium, and (d)
bacteria as the decomposers.
20. Producers :
These are mainly grasses of the family Graminae , a
large variety of herbs, some shrubs and Scattered trees.
Consumers:
Herbivores such as grazing mammals( eg. Cows, sheep,
deer, rabbit,buffaloes,etc.),insects (eg. Dysdercus, Coccinella,
Leptocorise, etc.),some termites and millipendes are the
primary consumers. The animals like fox, jackals, snakes,
frogs, lizards, brids ,etc. are the camivores feeding on
herbivores. These are the secondary consumers of the
grassland ecosystem Hawks occupty the tertiary trophic level
as these feed on the secondary consumers.
21. Decomposers :
These include bacteria of death and decay,
moulds and fungi (eg. Mucor, Penicillium, Aspergillus,
Rhizopus, etc.) These buing the minerals back to the
soil to be available to the producers again.
