This is one of the most important of the terrestrial ecosystems. Forest occupies roughly 40% of the land. In India however forest cover is woefully less and it occupies about 10-11% of the land surface.’ The various components of the forest ecosystem are:
The organic and inorganic contents of the soil and atmosphere constitute the abiotic components. Mineral elements, organic debris in the form of humus are the components, of the soil. Atmospheric humidity, precipitation, light are the other abiotic components. The amount of light reaching the forest floor is an important consideration in deciding the type of herbaceous vegetation and the growth of epiphytes. Biotic components These are:
The various types of herbs, shrubs and trees in the forest constitute the producers. The ratio of these depends on the climatic conditions. Mostly trees abound. All the trees may be of the same height or the canopy may show stratification as in tropical moist deciduous forests. In tropical rain forests usually the floor vegetation is not much as sunlight rarely touches the forest floor. The floor vegetation usually comprises of sciophytes.
Herbaceous plants requiring sunlight grow as epiphytes on the branches of trees. Other nonarborescent heliophytes become climbers or lianes. The important trees in a forest ecosystem are – Tectona grandis, Butea frondosa, Shorea robusta, Lagerostromia parviflora etc in deciduous forests Terminalia tomentosa, Diospyros melanoxylon, Acacia arabica, Chloroxylon Spp, Bauhinia etc in dry deciduous forest Quercus, Acer, Betula, Thuja, Piecea etc in temperate deciduous forests and Abies, Picea Pinus, Cedrus, Juniperus, Rhododendron, etc in temperate coniferous forests.
The forests are mainly classified into various categories based on the climate and species components in the vegetation cover. These are desert ecosystems,, Grassland, Rain forest, Tropical moist deciduous, Tropical dry deciduous, Alpine forests, Alpine scrubs etc.,
As usual these are of three categories- primary, secondary and tertiary. Herbivorus animals feeding on the leaves, tender shoots and fruits of producers are the primary consumers. These are ants, flies, beetles, locusts, leafhoppers, bugs, spiders etc., among small animals, Squirrels, Flying foxes, Mongooses etc are also primary consumers. Secondary consumers are carnivorous like snakes, birds, lizards, foxes etc. Birds may be primary consumers also. Tertiary consumers include top carnivores like lion, tiger etc. feeding on primary and secondary consumers.
Decomposing microorganisms like fungi and bacteria abound in the forest soil, particularly where leaf litter is plenty. Aspergillus, Coprinus, Polyporus, Ganoderma, Fusarium, Alternaria, Geastrum etc., among fungi, Bacillus, Clostridium, Pseudomonas etc., among bacteria and antinomycetes like Streptomyces, are the chief decomposers in a forest ecosystem. Tropical and subtropical forests have a rapid rate of decomposition than the temperate forests.