Rain forests, as the name suggests, are those forests, which are characterized by high annual rainfall of around 1750mm to 2000mm. The global distribution of equatorial rainforest is closely tied to the warm, moist climates that occur near to the Equator. Ecologists recognize this class of forests from a characteristic assemblage of features; the trees tend to have wide buttress roots that splay out near the ground, and the leaves tend to be large, evergreen and laurel-like, with an elongated tip (a `drip tip`) on the end of each leaf. Near to the Equator, the intense energy input from the sun produces the intertropical convergence zone (the ITCZ), a convection zone of rising air that loses its moisture as frequent, intense rainstorms. Despite the growth of vegetation in a rainforest, the actual quality of the soil is often quite poor. Rapid bacterial decay prevents the accumulation of humus. The concentration of iron and aluminium oxides by the laterization process gives the oxisols a bright red color and sometimes produces minable deposits like bauxite.

The largest tropical rainforests exist in the ((Amazon Basin))(the Amazon Rainforest), in Nicaragua (Los Guatuzos, Bosawás and Indio-Maiz), the southern Yucatán Peninsula-El Peten-Belize contiguous area of Central America (including the Calakmul Biosphere Reserve), in much of equatorial Africa from Cameroon to the Democratic Republic of Congo, in much of southeastern Asia from Myanmar to Indonesia and Papua New Guinea, northern and eastern Australia and in some parts of the United States. Outside of the tropics, temperate rainforests can be found in British Columbia, southeastern Alaska, western Oregon and Washington, the northern coast of California, Scotland and Norway, the western Caucasus (Ajaria region of Georgia), parts of the western Balkans, Japan, southern Chile, New Zealand, Tasmania, and parts of eastern Australia.

Despite their wide geographical separation, there are strong floristic similarities between all the world`s rainforest regions that reflect a common origin. Many of the same families and even genera of plants occur in rainforests on different continents, separated by thousands of miles of ocean water. It probably might be because of the exceptional dispersal abilities of certain plants that may have had their seeds carried across great distances by birds or ocean currents within the last few million years. There might be other reasons to this. There is fossil evidence indicating that that many of the world`s widely separated regions of rainforest were once linked together into continuous forest belts during times of moister and warmer climate.

Some striking facts about Rain Forests:
1. Rain forests serve as a shelter to more than half of the world`s estimated 10 million species of plants, animals and insects.

2. rainforests are not major consumers of carbon dioxide and like all mature forests are approximately carbon neutral. Recent evidence suggests that the majority of rainforests are in fact net carbon emmiters.

3. Rainforest plants are rich in secondary metabolites, particularly alkaloids. Biochemists believe alkaloids protect plants from disease and insect attacks. Many alkaloids from higher plants have proven to be of medicinal value and benefit.

4. One hectare (2.47 acres) may contain over 750 types of trees and 1500 species of higher plants.

5. At least 3000 fruits are found in the rainforests; of these only 200 are now in use in the Western World. The Indians of the rainforest use over 2,000.

6. Currently, 121 prescription drugs currently sold worldwide come from plant-derived sources. And while 25% of Western pharmaceuticals are derived from rainforest ingredients, scientists have tested less than 1% of these tropical trees and plants.

7. At least 80% of the developed world`s diet originated in the tropical rainforest. Its bountiful gifts to the world include fruits like avocados, coconuts, figs, oranges, lemons, grapefruit, bananas, guavas, pineapples, mangos and tomatoes; vegetables including corn, potatoes, rice, winter squash and yams; spices like black pepper, cayenne, chocolate, cinnamon, cloves, ginger, sugar cane, turmeric, coffee and vanilla and nuts including Brazil nuts and cashews.

8. Sufficient demand of sustainable and ecologically harvested Rainforest products is necessary for preservation efforts to succeed.

9. The U.S. National Cancer Institute has identified 3000 plants that are active against cancer cells. 70% of these plants are found in the rainforest. Today, over 100 pharmaceutical companies and several branches of the US government, including giants like Merck and The National Cancer Institute, are engaged in plant research projects for possible drugs and cures for viruses, infections, cancer, and even AIDS.

10. Many native tribes inhabit rainforests around the world. It was estimated that more than 1,000 tribes call it home. Today, only 250,000 natives still live in the Amazon.

Rainforests have evolved over millions of years to turn into the incredibly complex environments they are today. Rainforests represent a store of living and breathing renewable natural resources that for eons, by virtue of their richness in both animal and plant species, have contributed a wealth of resources for the survival and well being of humankind. These resources have included basic food supplies, clothing, shelter, fuel, spices, industrial raw materials, and medicine for all those who have lived in the majesty of the forest.

The Different Rain Forest layers:
The rainforest is divided into five different parts, each with different plants and animals, adapted for life in that particular area.

The Emergent layer: This layer contains a small number of very large trees which grow above the general canopy, reaching heights of 45-55 m, although on occasion a few species will grow to 60 m or 70 m tall, as they withstand the hot temperatures and the dry winds. This layer is inhabited by eagles, butterflies, bats and certain species of monkeys.

The Canopy Layer: This layer contains the majority of the largest trees, typically 30-45 m tall. Their branches touch, their leaves seem to fill every space where light may fall. The ground layer has a dense plant growth. The densest areas of biodiversity are found in the forest canopy. It is home to approximately 40% of all plant species, suggesting that perhaps half of all life on Earth could be found there.

The Understory layer: Regarded as the space between the Canopy and the forest floor, this layer is home to a number of birds, snakes, and lizards, as well as predators such as jaguars, boa constrictors, ocelots, and leopards. Armadillos also live here. The leaves are much larger at this level. Insect life is also abundant. Also called the shrub layer, this layer receives only about 2 to 5% of the sunlight shining on the rainforest region. This region consists of small trees, shrubs, and bushes. These plants are adapted to low light levels, and their large, tender leaves capture as much light energy as they can although very little plants can survive there. Some are dwarf palms, acanthus, and prayer plant.

Shrub Layer: Resting just above the floor, this layer consists of mainly large-leaved plants and small trees able to survive on the meager amount of light let through by the canopy.

The Forest Floor: This layer receiving only about 2% of the forests` sunlight is home to specially adapted plants. Because of the little amount of sunlight it gets, this region is relatively clear of vegetation. It contains decaying plant and animal matter, which disappears quickly due to the warm, humid conditions promoting rapid decay. Many forms of fungi grow here which help decay the animal and plant waste. A leaf that might take one year to decompose in a temperate climate will disappear in just six weeks on the rainforest floor. A high proportion of the nutrients in the system are locked in the large biomass (trees and other plant storage systems). There is heavy competition for these nutrients. This is why many trees are so shallow-rooted. Large mammals, such as tapirs, forage for roots and tubers. Insects, including termites, cockroaches, beetles, centipedes, millipedes, scorpions and earthworms, along with the fungi, use the organic litter as a source of food.

It has long been known that rainforests of India, Sri Lanka, Malaysia, Australia and New Guinea form a relatively coherent unit, sharing many floristic elements. The scattering of lands between Indochina in the northwest and Australia and New Guinea in the east more-or-less comprises the floristic region known as Malesia, but for present purposes it is too closely similar to the Indian region to be considered totally separately from it. All across the far eastern region there exists a strong floristic resemblance to the African tropics. Studies of the seasonal behavior of rainforest trees in equatorial Malaysia have indicated that even the relatively slight dip in rainstorm frequency that occurs twice each year is enough to act as a cue for a burst of leaf renewal and flowering in many species.

The equatorial rainforest in India occurs in two separate areas; along the strip of hills and mountains near to the west coast, the Western Ghats, and in the northeastern state of Assam close to the border with Myanmar (Burma). In both these areas, semi-evergreen rainforest is more widespread than evergreen forest, probably due to a long history of human influence, which has degraded the structure of the forest and its soils, and led to a more precarious water balance. The Western Ghats are more diverse than those of Assam, with over 4,000 plant species occurring in this relatively small area of hill land. Of these, 1,800 species are endemic to the Western Ghats, most of these being confined to the rainforest rather than the other drier vegetation types that occur mixed in with it.

The North Western Ghats montane rain forests is a tropical moist broadleaf forest ecoregion of southwestern India. It covers an area of 30,900 square kilometers (11,900 square miles), extending down the spine of the Western Ghats range, from Maharashtra state in the north through Karnataka to Kerala state in the south. The montane rain forests are predominantly evergreen laurel forest, dominated by trees of the laurel family (Lauraceae), including Litsea, Phoebe, and Cinnamomum. The South Western Ghats montane rain forests are an ecoregion of southern India, covering the southern portion of the Western Ghats range in Kerala and Tamil Nadu, at elevations over 1000 meters. They are cooler and wetter than the lower-elevation South Western Ghats moist deciduous forests, which surround the montane rain forests.

Today the Northeastern states of India have become the only region where Rainforest wealth of India survives. The state of Arunachal Pardesh is gifted with enormous wealth of wildlife and forested land. But today the rainforests of the northeast state of Assam are facing fast depletion. In the recent survey it has been discovered and that there is a continuous stretch of 800-sq-kms of virgin rainforests in upper Assam that spills over to Arunachal Pradesh is present in the Northeastern region of India. The newly discovered Joydihing -wildlife sanctuary comprises the Joypur reserve forest, Dirak reserve forest and Dihing reserve forest. It houses 32 species of mammals, more than 300 species of birds and several other rare and endemic wild species. A critical aspect of this forest zone is that of the 15 species of non-human primates found in India, seven inhabit in this belt. They include Rhesus Macaque, Assamese Macaque, and slow Loris, capped Langurs, pig-tailed Macaque, stam-tailed Macaque and Hoolock Gibbons. This rainforest stretch is also one of the largest elephant zone in India, through which more than 2,000 elephants migrate to Arunachal Pradesh every year.

The destruction of the far eastern rainforests has been exceptionally rapid during the last 50 years. The Indian and Sri Lankan rainforests have suffered badly as a result of increasing human populations and poorly controlled logging during the past few decades. The longer-term result of unsustainable exploitation is degradation in the quality of the forest resources for the people that benefit from them, and a loss of biological diversity. In Sri Lanka, uncontrolled deforestation occurred partly as a result of the breakdown of order resulting from civil war. In 1950, about 15 percent of the Earth`s land surface was covered by rainforest. Today, more than half has already gone up in smoke and the rate of destruction is still accelerating. More than 20 percent of the Amazon rainforest is already gone, and much more is severely threatened as the destruction continues. Fewer rainforests mean less rain, less oxygen for us to breathe, and an increased threat from global warming.