Forest Ecosystem is considered as an example of terrestrial ecosystem.
Forests are natural plant communities with dominance of phanerogams. In India forests occupy approx.1/10 of the land area. Indian forests can be divided into the 4 broad categories.
1. Tropical (wet evergreen, semi-evergreen, moist deciduous and dry deciduous).
Forest ecosystem includes :
1. Abiotic components :
This includes inorganic and organic substances present in the atmosphere and soil. The climate (temperature, light, rainfall etc.) and soil (minerals) vary from forest to forest. In addition to minerals the occurrence of litter is the characteristic feature of majority of forests. Through litter decomposition approx. 90% energy trapped in the ecosystem by autotrophs dissipates into space as heat energy. The litter fall increases with decreasing latitudes.
2. Biotic components :
(A) Producers : They are represented mainly by trees but shrubs and ground flora are also found. Depending upon the kinds of forests the flora varies.
(B) Consumers :
(i) Primary consumers (herbivores) are small animals feeding on tree leaves, include ants, beetles, flies, bugs, spiders, leaf hoppers etc. neelgai, deer, elephants, moles, squirrels and fruit bats are large animals which feed upon shoots and/or fruits,
(ii) Secondary consumers are different kinds of birds, snakes, lizards, feeding on primary consumers.
(iii) Tertiary consumers are tiger and lion are the top carnivores.
(C) Decomposers : Streptomyces (sps of Angiococus, Bacillus and Pseudomonas) and Fungi (Aspergillus, Polyporus, Alternaria, Fusarium, Trichonderma) are helpful in decomposing the litter. Further litter decomposition found to be slow in cooler and drier areas, therefore, sometimes its accumulation on the soil surface makes a thick layer.