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Tropical Rainforests

Tropical rainforests are one of the most complex and fragile ecological systems in the world. Not much has been studied on these ecosystems, mainly due to barriers like extreme climatic and geographic conditions. These forests are characterized by a variety of vegetation types due to climatic, edaphic and biogeographic factors. According to Richards, (1952), the moist forests in Southeast Asia are among the oldest types of forests in the world, being at least 30 million years old.

In ecological terms, rainforests have been defined as “multi-storied, closed, broad leaved forest vegetation with a continuous tree canopy of variable height and with characteristic diversity of species and life-forms” (Sneadaker, 1970). Tropical rainforests in particular possess an astonishing array of flora and fauna. In fact, at least half of the earth’s species are found in rainforests. Rainforests belong to the tropical wet climate group with an average rainfall of 125 to 660 mm yearly. The temperature in a rainforest rarely gets higher than 34 °C or drops below 20 °C; average relative humidity is between 77 and 88 percent. There is usually a brief season of less rain. In monsoonal areas, there is a real dry season. Almost all rainforests lie near the equator.

Rainforests now cover less than 6 percent of earth’s land surface. Scientists estimate that more than half of the entire world’s plant and animal species live in tropical rainforests. Tropical rainforests produce 40 percent of earth’s oxygen. The tropical regions are endowed with a remarkably high level of biological diversity and habitat heterogeneity; so there are roughly twice as many species in tropical regions in comparison to temperate ones. The environmental impacts of transforming forests through mining, forestry activities, shifting cultivation, agricultural development, wildlife exploitation and major engineering works are manifold. Inevitably, they diminish the forests, and destroy the essential discharge and waste processing capacity of the drainage system.