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Lecturer / Civil Engineering
V.S.V.N Polytechnic College,
Anecosystemis acommunityof living organisms (plants, animals and microbes) in conjunction with thenonliving componentsof 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& Melillo2001)
Components of Ecosystem
An ecosystem consists of two main components
Abioticor Non-living components.
1. Inorganic substances
2. Organic compounds
3. Climatic factors
Biotic or Living components.
1. Autotrophsor Producers
2. Heterotrophsor Consumers
3. Decomposers or Saprotrophs
Abioticor 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,
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
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
plants, fungi, and bacteria
live on dead matter -AKA
Herbivores: plant-eating animals
Carnivores: meat-eating animals
Omnivores: consume both plants
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.
Producersconvert 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.
Since practically all organisms may be consumed by more than one species, many interactionsoccur 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,andrabbits 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 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.
There is a decrease in the overall energyin each level as you move up the food web.
This means that there is much moreenergy in the producer level in a food web than at the consumer levels.
Also, this means that there is moreenergy at the primary consumer level than at the secondary consumer level.
Each consumer level of the food pyramid utilizes approximately 10% of its ingested nutrients to build new tissue.
This new tissue represents foodfor the next feeding level.
The remaining energy is lostin 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.
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
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 Ecosystem
1.Terrestrial ecosystems (grasslands, forests, desert ecosystems)
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.
It includes saline water ecosystems like oceans, seas, estuaries etc.,
It includes all freshwater ecosystems like ponds, pools, lakes, rivers, streams etc.,
It includes the ecosystems of air, forests, grass lands, deserts, etc.,
These are man made ecosystems of air, forests, grasslands, deserts, etc.,
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
River ecosystems are prime examples of loticecosystems
Loticrefers 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
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 comprises the ocean and sea
Marine ecosystemsare among the largest of Earth'saquatic 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
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
A desert is a landscape form or region that receives very little precipitation.<250 mm per annum.
It covers 1/5thof 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.
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.
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Lecturer / Civil
V.S.V.N.Polytechnic College, Virudhunagar