Prepared by

M.Shanmugaraj M.E.,

Lecturer / Civil Engineering

V.S.V.N Polytechnic College,

Virudhunagar

Tamil Nadu

India

ECOSYSTEM

Definition

An ecosystem is a community of living organisms (plants, animals and microbes) in conjunction with the nonliving components of their environment (things like air, water and mineral soil), interacting as a system.An ecosystem is formed by the interactions

between all living and non-living things The sum of all of the biological and non-

biological parts of an area that interact to cause plants to grow and decay, soil or sediments to form, and the chemistry of water to change (Aber & Melillo 2001)

Components of EcosystemAn ecosystem consists of two main components

Abiotic or Non-living components.

1. Inorganic substances

2. Organic compounds

3. Climatic factors

Biotic or Living components.

1. Autotrophs or Producers

2. Heterotrophs or Consumers

3. Decomposers or Saprotrophs

Abiotic or Non-living components.

It includes the non living substances of the

environment eg. Water, Soil, Air, Light,

Temperature, Minerals, Climate, etc.

Biotic or Living components

The biotic factors include the living organisms of

the environment. Eg. Plants, Animals, Bcteria,

Viruses, etc.,

Ecosystem structure

Producers/autotrophs--normally plants

that capture the sun’s energy, powering all

other life on Earth (also chemosynthetic bact.)

Consumers/heterotrophs--must eat to get

food

Decomposer--bacterium, fungus, etc. feeds

on dead organisms from all trophic levels,

returning nutrients to the soil

Producers/Autotrophs

The organisms which carry out photosynthesis constitute

the Producers of an ecosystem. Eg. Plants, Algae and

Bacteria

The producers use inorganic substances of the abiotic

factors and convert them in to organic food materials.

Consumers or Heterotrophs

Consumers are organisms whish eat other

organisms. All animals are consumers.

They are further divided in to primary consumer,

secondary consumer, tertiary consumer

Types of Heterotrophs:

Saprophytes: include those

heterotrophic

plants, fungi, and bacteria

which

live on dead matter - AKA

decomposers

Herbivores: plant-eating animals

Carnivores: meat-eating animals

Omnivores: consume both plants

and meat

Reducer or Decomposer

These are organisms that break up the dead bodies

of plants, animals and their waste products.

They include fungi and certain bacteria

The enzyme secreted by the fungi and bacteria

digest the dead organisms and the debris in to

smaller bits or molecules.

Theses molecules are absorbed by the reducer and

release molecules to the environment as chemicals

used by the producers.

Food Chains and Webs:

If an ecosystem is to be self-sustaining it must

contain a flow of energy.

Those life activities that are characteristic of living

organisms require an expenditure of energy.

The pathways of energy through the living

components of an ecosystem are represented by

food chains and food webs.

Producers convert the radiant energy of the sun

into the chemical energy of food.

A. Food chain: involves the transfer of energy from

green plants through a series of organisms with

repeated stages of eating and being eaten

B. Food web: In a natural community, the flow of

energy and materials is much more complicated

than illustrated by any one food chain.

Food Chain

Food Chain

Since practically all organisms may be consumed by more

than one species, many interactions occur along the food

chains of any community.

Food Web Interactions:Producers: (plants) – the energy of the community is derived

from the organic compounds in plants - (grass in the web

above)

Primary Consumer: (always a herbivore) - feeds on plants

(mice, grasshoppers,and rabbits in the web above)

Secondary Consumer: (always a carnivore) -- feeds upon other

consumers (frogs, sparrows, snakes, and foxes above)

Omnivores may be primary or secondary consumers.

Decomposers: break down organic wastes and dead organisms to

simpler substances (ex. bacteria of decay)

** Through decomposition, chemical substances are returned to

the environment where they can be used by other living

organisms.

Energy Flow:

Energy flows through ecosystems in one

direction, typically from the Sun, through

photosynthetic organisms, including green plants

and algae, through herbivores, to carnivores, and

finally decomposers.

Energy Flow

There is a decrease in the overall energy in

each level as you move up the food web.

This means that there is much more energy in

the producer level in a food web than at the

consumer levels.

Also, this means that there is more energy at

the primary consumer level than at the

secondary consumer level.

Energy Transfer:

Each consumer level of the food pyramid utilizes

approximately 10% of its ingested nutrients to build new

tissue.

This new tissue represents food for the next feeding level.

The remaining energy is lost in the form of heat and

unavailable chemical energy. Eventually, the energy in an

ecosystem is lost and is radiated from the earth.

Thus, an ecosystem can not survive without the constant

input of energy from the sun.

Ecological Pyramid The energy of organisms gradually decrease from the

producer level to the consumer level.

This can be represented in the form of a pyramid called

Ecological Pyramid

Graphical representation of the energy of the successive

trophic levels of an ecosystem.

It was first described by Charles Elton in 1927

In the ecological pyramid, the producer forms the base and

the final consumer occupies the apex

Types of ecological pyramid

1. The pyramid of number

2. The pyramid of biomass

3. The pyramid of energy

Inverted Pyramid In some ecosystems, the number and the biomass of the

producers are less and those of consumers are more.

This type of ecosystem produces a pyramid where the apex is

directed downwards.

This type of pyramid is called Inverted Pyramid

Types of EcosystemNatural

1.Terrestrial ecosystems (grasslands, forests, desert

ecosystems)

2.Aquatic ecosystem

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

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

Artificial

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

Marine Ecosystem:

It includes saline water ecosystems like oceans, seas, estuaries etc.,

Limnic Ecosystem:

It includes all freshwater ecosystems like ponds, pools, lakes, rivers, streams etc.,

Terrestrial Ecosystem:

It includes the ecosystems of air, forests, grass lands, deserts, etc.,

Artificial Ecosystem:

These are man made ecosystems of air, forests, grasslands, deserts, etc.,

Pond Ecosystem

A pond is a suitable example for aquatic ecosystem.

The pond ecosystem is formed of abiotic factors and

biotic factors

The abiotic factors of the pond ecosystem are water,

CO2, O2, inorganic compounds, organic compounds,

light, temperature, pressure, pH, etc.

The biotic factors of the pond ecosystem are plants and

animals

Pond Food Web

River Ecosystem

River ecosystems are prime examples of lotic ecosystems

Lotic refers to flowing water

It is a running water ecosystem

It has water current. Water is in motion

The major rivers of India are Ganga, Yamuna, Bramaputra,

Thungapatra, Cauveri, Vaigai, etc.

It is made up of two components, namely abiotic

components and biotic components

The abiotic components are the non-living factors such as

ricer, soil, water, light, temperature, etc.

The biotic components are the living factors

Lake Ecosystem

A lake is a large fresh water body of water which

has no connection with the sea.

It is a standing water body (Lentic)

It is of great depth

The lake is of three types, oligotrophic lake,

eutrophic lake and dystrophic lake.

Oligotrophic lakes are young lakes, they are deep, they are poor in

fauna and flora.

Eutrophic lakes are swallow. They are shallow but rich in fauna and

flora

Dystrophic lakes are swallow or deep. They are poor in fauna and flora

Marine Ecosystem Marine ecosystem comprises the ocean and sea

Marine ecosystems are among the largest of Earth's aquatic

ecosystems.

Marine waters cover two-thirds of the surface of the Earth

Marine ecosystem has a wealth of aquatic food

The marine ecosystem consists of abiotic factors and biotic factors

Marine Ecosystem

Estuarine Ecosystem

Estuary is the meeting place of Sea and River

It is a shallow water body where river water mixes with

the sea water

It is rich in nutrients, it is a salt water body

It is a good fishing ground for fish farmers

The Ectuarine ecosystem consists of abiotic factors and

biotic factors

Estuaries

Forest Ecosystem

It consists of large trees and thick vegetation

The forest is a terrestrial ecosystem

Forest food web

Desert Ecosystem A desert is a landscape form or region that receives very little

precipitation.<250 mm per annum.

It covers 1/5th of earth’s land surface.

Most of the deserts are composed of sand (ergs) and rocky

surface (reg).

Temperature ranges from 50 degree C to nearly zero level

within a single day.

Plants and animals have different morphological and anatomical

modifications to reduce water loss from the body.

Vegetations known as ‘xerophytes’ have modifications like pulpy stem to store water and wax covered thorny leaves to reduce transpiration. The roots are very long to reach the water table.

Animals such as reptiles, rodents, wolves etc hide themselves in daylight and come out at night.

Desert

Why should we care about Ecosystem

Ecosystem ecology provides a mechanistic basis for understanding the Earth

System

Ecosystems provide goods and services to society

Human activities are changing ecosystems (and therefore the Earth System)

When an ecosystem changes, such as a pond dries out, or a new

organism is introduced to the ecosystem, it affects the entire process,

from the organism's food supply to the nutrients and chemicals

available in the ecosystem.

Humans largely affect the biosphere, sometimes obviously, and other

times, obliviously. Pollution in the ocean or the cutting down of trees

for construction purposes can destroy an ecosystem and put organisms

in grave danger.