Ecosystems

Ecosystems

A community and its physical environment is called its Ecosystem. An ecosystem is a biological  environment consisting of all the organism living in a particular area, as well as all the non- living (abiotic), physical components of the environment with which the organisms interact, such as air, soil, water and sunlight.

      Ecosystem is an open system with inputs, internal transfers and outputs of energy and nutrients.  Sunlight is the initial energy source for nearly all ecosystems. The different types of ecosytems are

(i)                  Natural ecosystem

(a)    Terrestrial ecosystem

(b)   Aquatic ecosystem

(c)    Lentic (lake, pond or swamp)

(d)   Lotic (river, stream or spring)

(ii)                 Artificial Ecosystems

The species that live and interact in an area constitute an ecological community.

Ecological communities are loose assemblages of organisms. The organisms in a community can be divided  into  trophic levels ( the position  of an organism in food chain) based on the source of their energy. Primary producers get their energy from  sunlight . Herbivores that get their energy  by eating primary producers are primary consumers;  organisms that get their energy by eating herbivores and secondary consumers; and so on. A sequence of interactions in which  a plant is eaten by a herbivore, which in turn eaten by  a secondary consumer, and so on, is known as food chain. Food chains are usually interconnected to make a food web because most  species in a community eat and are eaten by more than one species . Most communities have three to five tropic levels. Energy and biomass decreases as it flows from lower to higher tropic levels and thus can be represented in the form of pyramid. Most of the energy ingested by organisms that is converted to biomass is eventually consumed by decomposers.