Ecosytem The term Ecosystem was first proposed by

ecologist A. G. Tansely who defined ecosystem as “ the system resulting from the integration of all the living and non living factors in the environment”

• A community of living organisms interacting with one another and with its non-living physical and chemical environment.

Or• An Ecosystem is a region in which living

organism interact with their environment and these interactions perpetuate the community and retain stability under varying conditions.

Classification of ecosystem

Natural vs Artificial Ecosystem

Structure of ecosystem: Components

Producers

Producers make their own food

Green plants use energy from the sun to make food

Producers are on the bottom of the food chain

Consumers

Consumers hunt, gather, and store food because they cannot make their own.

Three Types of Consumers

Herbivores

Carnivores

Omnivores

Herbivores

Animals who eat plants such as: grasshoppers rabbits squirrels deer pandas

Carnivores (secondary consumers) Meat eaters and feed on

herbivores are known as secondary consumers

Eg dog, fox, wolf etc.

Carnivores (tertiary consumers) Carnivores which prey

upon other carnivores but are not eaten themselves. They constitute the terminal end of predator of grazing food chain tigers lions hawks

Omnivores

Animals who eat both plants and animals such as: humans bears

Decomposers Organism that feed on dead and decaying

matter and convert the organic material in to organic material are called decomposers

They help in nutrient recycling and known as recycling agent of the nature

In absence of recycling nutrients earth would be converted in to a vast dump of dead organism

Microorganisms that are able to break down large molecules into smaller parts

Abiotic components Physical factors: Sunlight, shade, intensity

of solar flux, length of day , temperature, annual rainfall (precipitation), latitude, altitude, soil type, water availability

Chemical factors: Availability of essential nutrients such as carbon, nitrogen, phosphorous, potassium, oxygen, sulfur, percentage of water and air in soil, salinity of water, oxygen dissolved in water

Functioning of Ecosystem

The function of ecosystem can be studied in following terms

Food chain Mineral nutrient cycle Energy flow

Food chain

The transfer of food energy from the source through a series of organism by regular eating and eaten up

In food chain each stage of transfer of food energy is known as trophic level

Therefore trophic level refers to successive levels of energy flow that form the link of food chain

Types of Food Chains

Aquatic- Water-related food chains with sea plants and animals

Terrestrial- Land-related food chains with land plants and animals

Type of food chain Grazing food chain: Common in nature.

Producer form the first link , herbivores as second and secondary consumer as the third

Detritus food chain: The organic waste and dead matter derived from grazing food chain is termed as detritus. Detrivores are the animal that consume detritus and in doing so contribute to decomposition and recycling of nutrient

Eg algea, bacteria, earthworms, millipedes Organism in this food chain are generally

smaller, and functional role do not fall in catagories

However grazing and detritus food chain are interlinked

Food webs

It is not possible to depict the real world by means of simple food chain, because the interconnection between different trophic level in real world are extremely complex

Various food chain are interlinked with each other and these interlocking pattern formed by several food chain linked together are called food web

Ecological Pyramids

An ecological pyramid is a diagram that shows the relationship amounts of energy or matter contained within each trophic level in a food web or food chain.

Energy Pyramid only 10% of the energy available within one trophic level is transferred to organisms at the next trophic level.

Pyramids Continued

Biomass pyramids show the total amount of living tissue available at each trophic level. This shows the amount of tissue available for the next trophic level.

Numbers pyramid shows the number of species at each trophic level.

Because each trophic level harvests only about one tenth of the energy from the level below, it can support only about one 10th the amount of living tissue.

PYRAMID OF NUMBERS

Shows the number of organisms at each trophic level per unit area of an ecosystem.

Pyramid of Numbers

Pyramid of numbers displays the number of individuals

at each level. 1 owl

25 voles

2000grass plants

PYRAMID OF BIOMASS

The total amount of matter present in organisms of an ecosystem at each trophic level is biomass.

Biomass is preferred to the use of numbers of organisms because individual organisms can vary in size. It is the total mass not the size that is important.

Pyramid of biomass records the total dry organic matter of organisms at each trophic level in a given area of an ecosystem.

Biomass PyramidsBiomass PyramidsDisplays the biomass at each trophic level.

PYRAMID OF ENERGY

Shows the amount of energy input to each trophic level in a given area of an ecosystem over an extended period.

1.Why will this type of pyramid never be inverted?

Energy PyramidEnergy Pyramid

Fig. 4–19

In nature, ecological efficiency varies from 5% to 20% energy available between successive trophic levels (95% to 80% loss). About 10% efficiency is a general rule.