File Catalog

Ecosystem

          An ecosystem is a complex set of relationship among the living resources, having habitats of an area which include plants, animals, birds, water, soils, micro organisms and people.

                An ecosystem consists of biological community which occurs in the same area, physical and chemical factors that make up abiotic environment.

Ecosystem can be defined as "the system of living organisms and their environment which interacts with one another and exchange the materials”.

Components of Ecosystem

                An ecosystem comprises two basic components namely

Ø  Biotic Components

The living organisms which are present in the ecosystem constitute biotic component and are classified into:

o   Autotrophs/Producers: The organisms which can prepare the food materials from the environment. Examples: Green plants, Photosynthetic and chemosynthetic bacteria.

o   Heterotrophs/Consumers: The organisms which cannot prepare the food materials and are dependent upon autotrophic organisms. These are sub divided into two types as follows:

·         Macro Consumers: The organisms which feeds on different kinds of food materials and are of three types as follows:

§  Primary Secondary Consumers/Herbivores/ /Non-autotrophic producers:

The organisms which feeds on the producers. Examples: Goat, Sheep.

§  Secondary Consumers/Omnivores:

The organisms which feeds on producers and herbivores.                                    Examples: Cat, Dog

§  Tertiary Consumers /Carnivores/ Predators: The organisms which feeds on omnivores and herbivores                                        Examples: Lion, Tiger

·         Micro Consumers/Decomposers/Saprotrophs/Osmotrophs/Transformers

The organisms which feeds on complex organic substances by converting them into simple inorganic substances.

These are vital components of the nutrient cycle which plays a key role in recycling the materials in an ecosystem hence also called as disposers/scavengers

Examples: Saprophytic bacteria and fungi.

Ø  Abiotic Components

The non-living, physic-chemico factors like air water, soil and some compounds of the environment constitute abiotic components. They are classified into 4 categories as follows:

·         Climatic Factors(Climatic regime and physical factors)

-          Light, humidity, atmospheric temperature , wind etc.,

·         Edaphic factors(Structure and composition of soil)

-          Soil, organic matter, soil organisms etc.,

·         Inorganic factors: water, Carbon, Sulphur,Nitrogen,Phosphorous etc.,

·         Organic factors: Proteins, Lipids, Carbohydrates etc.,

The important abiotic factor in an ecosystem is radiant energy which obtains from the sunlight.

Green plants absorb radiant energy and convert it into chemical energy (ATP) then finally to potential energy which is stored in the form of food.

Radiant energy → Chemical energy → Potential energy

Energy flow is always UNDERECTIONAL

The living organisms utilize the materials from the environment after the death and decay of the organisms, materials again returned back to the environment known as biogeochemical cycle or mineral cycle.

Trophic Levels

It is the feeding position in a food chain such as producers, herbivores and carnivores.

Green plants from the first trophic level are producers, cows from the second trophic level are primary consumers, lions from the third trophic level are secondary consumers, eagle from the fourth trophic level are tertiary consumers, and bacteria from the fifth trophic level are decomposers.

Note: Sun is the main source for all these levels

Ø  Food Chain

The sequence of the transfer of food energy from one organism to another organism in an ecosystem known as food chain.

·         Example

In this rose plant is the primary producer, aphid is the primary consumer because it sucks the juice of the plant, beetle is the primary carnivore because it eats the aphid, chameleon is the secondary carnivore because it eats the beetle, hawk is the tertiary carnivore because it eats the chameleon, hawk eventually dies and remains are broken down by decaying bacteria and fungi are decomposers.

Rose Plant→Aphid→Beetle→Chameleon→Hawk→Bacteria

Ø  Food Web

In an ecosystem different food chains are inter related with each other to form a web known as food web.

Ecological Pyramid

                It is a graphical representation designed to show the number, energy relationships and biomass of an ecosystem

It was first described by Charles Elton hence also known as Eltonian Pyramid. Three types of ecological pyramid can usually be distinguishes namely:

Ø  Number Pyramid

It represents the number of organisms in each trophic level. This pyramid contains a relationship between the number of herbivores and carnivores.

·         Types

§  Upright Pyramid: Aquatic ecosystem

Number of organisms fewer and fewer. 

§  Partly Upright Pyramid: Forest ecosystem

Few producers support more primary consumers but they are less secondary and tertiary consumers.

§  Inverted Pyramid: Parasitic ecosystem

Number of organisms depend on the lower levels and grows towards the apex.

Ø  Biomass Pyramid

It represents the amount of energy contained in biomass at different trophic and also demonstrates the amount of matter lost between trophic levels.

·         Types

§  Upright Pyramid: : Forest ecosystem

Combined weight of producers is larger than the combined weight of the consumers.

§  Inverted Pyramid: Aquatic ecosystem

§  Combined weight of producers is smaller than the combined weight of the consumers.

 

Ø  Energy Pyramid

It represents the total amount of energy consumed by each trophic level.

·         Types

§  Upright Pyramid

Total amount of energy available for utilization in the layers above, less than the energy available in the lower levels.

..........................................THE END............................................