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A biotic community intreacts with enviornment in
which it lives. for example a human being intreacts
with animals, plants for foods and also intreacts with
neighbours. He also intreacts with enviornment which
supplies him materials and energy. This constitute the
ecosystem. Thus ecosystem may be defined as
 “ The entire intreacting system of
organism together with environmental factors with
which they intreacts. In other words , it is self
sustained community of organisms”
It includes all the communities of an area
functioning with their physical enviornment. For
example ,a pond lakes river, garden crop field are
common examples of enviornment
Abiotic substances  These includes air, water,
soil, basic elements and compounds of the
environment.The abiotic environment of
ecosystem are divide into three parts:
(a) The physical factors such as temperature,
relative humidity precipitation etc.
(b)
Inorganic substances such as water, carbon,
nitrogen etc.
(c)
Organic substances such as protien,
carbohydrates lipids etc.
These are buildings blocks of living
body and link between biotic and abiotic
components
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The term ecosytem was first purposed by A>G Tansely
(1935) who defined it as ecosystem is self sustained
community
The term ecosystem is made up of two words :
(eco and system). Eco means ecological sphere or
region of space where living things can exists while
system means intreacting organism living in a
particular habitat. Thus the system resulting from the
integration of all living and non living factors of
organisms is called ecosystem.
An ecosystem is dynamic entity composed of a
biological community and its associated abiotic
environment.
The materials continually cycle fron the
environment into living organisms and from
organisms by death into the environment. The
cycle called bio-geological cycle. Solar energy
continuosally trapped from the sun, which is
the ultimate sources of energy
And energy is lost via respiration and heat losses
and escapes to environment.
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It includes all living organisms and its
environment. The biotic component can be
divided into two major groups:
(a) Autotrophs
(b) Hetrotrophs
(a) Autotrophs (auto=self, troph= nourshing):
self food producing organisms are known as
autotrophs. They depend on the environment
for their food materials utilize sunlight for their
f o o d ,
h e n c e
c a l l e d
producers………………………………….
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Hetrotrophs(Hetro-other; trophs nourshing)
The hetrotrophs are the organisms mostly
animals that cannot utilizes sunlight directly
for their food prepration , because they do not
have chlorophyll. Hence they consumes plants
and their products produced by autotrophs. In
this complex organic substances produced by
plants are broken down into smaller forms.
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Living organisms which consumes food,
synthesied by producers are called consumers.
Based on dependency, they are classified into
three major groups.
Primary totally dependent on plants
Secondary dependent on primary
Tertiary They depend on both primary and
secondary.
The placements of individuals organisms
depend upon the type of food they eat and
occupation of organism in food chain.
(1) Herbivores : plant eating organism
 (2) Carnivores : organisms eating herbivores
 (3) Omnivores : Organisms eating herbivores and
carnivores
This classification is easy to understand
because the terms directly indicate (e) type of food they
eat.
1st order consumer, 2nd order consumer,3rd order
consumer, 4th order consumer
GRASSGRASSHOPPERFROGSNAKEHAWK
Hence grass is producer, grasshoper is 1st order frog is
2nd snake is 3rd , hawk is 4th order
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The main function of ecosystem are as:
 (1) Flow of energy (a) from sun to producers
(b) producers to consumers (c) consumer to
decomposers
 (2) Cyclic use of materials The chemical
elements composing the abiotic components
are circulated in an ecosystem starting from
nutrients pool (soil) to produces , producers to
consumer
Consumers to decomposers and then back to
pool.
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Flow of energy takes place in an ecosystem
takes place through food chain . In an
ecosystem , unidirectional flow of energy is
normally observed . Unlike the nutrients like
(C,N etc) which moves In cyclic manner and
care reused by producers after flowing through
food chain, energy is not reused in ecosystem.
This energy flow is based on two laws of
thermodynamics .
(1) First law of thermodynamics
(2) Second law of
thermodynamics………………………………….
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Energy can neither be created nor be destroyed
but can be transformed from one form to
another is first law of thermodynamics. The
solar energy trapped is converted into
biochemical energy.
According to second law “energy cannot flow
from a cold body to hot body by itself” one of
the example is such a photosynthesis ,where
conversion of light energy into potential
chemical energy is invariably accompanied
with dispersion of some energy as heat energy .
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“An ecological pyramid is graphical
representation of ecological parameters like
number or biomass or accumulated energy at
different tropic levels in food chain of an
ecosystem.
The idea of ecological pyramid was
developed by Charles Eltro , an English man .
So ecological pyramid is also called Eltronian
pyramids.
In these pyramid the first tropic level i.e. producer
forms the base and the successive level i.e. herbivores
at middle and next carnivores in simple form, if we
arrange the organism in a food chain according levels
,they often form pyramid.
 Type of pyramid they are of 3 types
(1) Pyramid number (2) Pyramid biomass
(3) Pyramid of energy
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It shows the relationship between the
producers,herbivores and carnivores at
successive tropic level in terms of their
number. Different shapes in ecosystem.
(1) Grassland ecosystem: producer are grass ,these
numbers gradually shows decrease towards
apex. The primary consumer are rabbit, cow,
goat and are lesser in number than grass. The
secondary consumers snakes, wolves and
lizzards and are less than herbivores
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In this the number of producers per unit of
space may be little for example a single tree
might support a greater number of herbivores
e.g. Fruit eating birds. The herbivores in turn
support still greater number of carnivores
The amount of living material present in an
organism are called biomass. It is measured as
fresh and dry.
(1) Grassland ecosystem: here biomass present in
grass is more than present in herbivores and
that of herbivores more dependent than
carnivores
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Out of these three types of ecological pyramids
, the energy pyramid gives the best picture of
overall nature of ecosystem. It is picture of
rates of passage of food mass through food
chain. There is always a gradual decrease in
energy content of successive tropic levels from
producer to consumers. Because there is also a
loss of energy. By respiration and other
process
An ecosystem is not static in nature. It is
dynamic in nature and changes its structure as
well as function.
Ecological succession is defined as orderly
process of changes in the community structure
and function with time mediated through
modifications in physical environment
cumulating in an ecosystem.
Ecological succession are different types.
(1) Hydrach starting in watering area lihe
ponds lakes. The pioneer community which are
phytoplanktoms, are replaced by roots
submerged plants.
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Growths of these plants keep on adding organic
matter and after death thus layer of soil builds
up and shallowing of water takes place. Then
stage is come where plants are slightly on
water slightly on lands.
Xerosere this type of succession originates on
bare rocks which is deficient I n water and
organic matter. The pioneer community here
consist of foliose lichens. These lichens produce
some weak acid and help in disintegration of
rocks
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there growth helps in building up gradually
organic matter, humus, soil. Then followed by
herbs, shrubs and finally the forest trees.
Thus, succession tends to move
towards mesic conditions whether starts from
moist or dry conditions and finally result into
trees……….
For the sake of study ecosystem are divided in
two main categories:
(1) Natural ecosystem
(2) man made ecosystem
Natural ecosystem are of three types
A Terrestrial B fresh water ecosystem
C Marine ecosystem
A large geographical area with its specific and
complex flora and fauna called biome. The
type of climax vegetation of a biome depends
upon the physical factors like nature of soil,
amount of rainfall etc.
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Forest cover about 1/12th of earth surfaces but
half of the worlds flora and fauna. Forest are
the natural community with dominance of tress
they cover about 40 percent of the land. There
are of three types:
(1) Tropical rain forest (2) Temperate deciduous
forest (3) confereous forest.
Tropical forest contain high humidity
Deciduous forest experience : temperature, rain
cold etc.
Confereous forest have short summers, long
and cold winters.
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There are mainly two component
(1) Biotic
(2) Abiotic component
 Abiotic component = this component consist of
organic and inorganic substances in soil and
atmosphere. The climate are vary from forest to
forest.
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Biotic component= it contain s as :
 Producers : this component consist of living
organisms such as producers consumers and
decomposers. In the forest there are lot of tress
like Dipterocrapus ( rose wood), tectona
grandis(Teak) etc.
 consumers: these feed on producers include
primary, secondary, tertiary.
The grass land ecosystem occupies 19% of earth
surfaces. The grass land biome occur in regions ,
where the climate is cool to cold during winters
and in summers. It has also two ecosystem:
(1) Abiotic ecosystem these include nutrients
present in soil and atmosphere. Thus elements
like C,H,O,N etc. are supplied by carbon dioxide ,
water present in air and soil of the area.
(2) Biotic component it has following parts
Producers the grass land are characterized by
treeless plant dominated by variety of grass
species main species are cynodon, cenchrus etc.
(1) Consumers the various types of consumers
are as :
Primary consumers the herbivores feeding on
grass such as animals like cows, goat etc.
Besides them there are also some insects
species like leptocorisa dysderus etc.
Secondary consumers snakes lizards etc.
Tertiary consumers hawks which feed
secondary.
(2) Decomposers several fungi and bacteria
decay the dead organic matter of different
forms .
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These are characterized by
(1) Desert around 1/5th of earth surfaces
(2) due to deficiency of water and high
temperature of desert , desert having scanty
flora and fauna
(3) days are extremely hot and nights are cold
(4) some animals like ants spiders lizards
snakes insect eating birds are present in this
ecosystem
There are many kinds of aquatic ecosystem
mainly fresh water ecosystem and marine
ecosystem. They differ widely with regards to
abiotic factors and living organisms. The
important ecosystem are as follows as
Ponds ecosystem pond ecosystem is an example
of lentic ecosystem , this ecosystem rich in
vegetation , micro organisms plants and
animals these are having following zones as
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Litorial zones this is a shallow water zones
and includes variety of floating organisms &
plants here penetration of light is very high.
And rich in nutrient area
Limentic zones  this is open water zones here
penetration of light is small than litorial zones
and contain phytoplanktoms
Profoundal zones this is deep zones. Here
biological activity is intense and are adapted to
cold water.
It includes two components
(1) Abiotic component
(2) Biotic component
Abiotic component it contains inorganic and
organic components. Only small amount is
form in soluble form and large amount is
present in bottom sediments and in organisms.
Biotic component it includes producers and
consumers. E.g. volvox anabaena are the
primary and mysids lycops are secondary.