Fact Sheet – The Rainforests

Tropical rainforests cover around 6% of the Earth’s surface, and are found around the Earth’s equator. There are tropical rainforests across parts of South America, Central America, Africa, Southeast Asia and Australasia. They are damp, warm and dense forest, and home to millions of plants and animals. The play a vital role in the Earth’s ecology, and generate up to 40% of the Earth's oxygen. The rainforests recycle and clean water.

Rainforests play a stabilising role in the greenhouse effect which traps heat inside the atmosphere. The trees and plants fix carbon dioxide from the atmosphere by trapping it in their roots, stems, leaves, and branches.

The largest tropical rainforests exist in the Amazon in South America,in the equatorial portions of Africa from the Democratic Republic of Congo to Cameroon, in Asia, from Papua New Guinea and Indonesia to Myanmar, and Eastern Queensland, Australia.

Scientists divide the rainforest into 4 layers or strata. Starting from the top, these are:

Emergent: Giant trees that are much higher than the average canopy height. This layer houses many birds and insects.

Canopy: The canopy is the roof of the rainforest, consisting of the tops of the trees, the flowers and fruit and the animals that feed there. The canopy is home to birds, insects, tree frogs and mammals.

Understorey: A dark, cool environment under the leaves but over the ground. Here the air is still, the humidity high, and the heat constant. Above the small plants of the forest floor, the birds and butterflies make this their domain, although they may venture up or down.

Forest Floor: This area is where seeds and fruit fall, and is teeming with animal life, especially insects. The largest animals in the rainforest generally live here. There is much variability in the forest floor - in some areas it floods periodically, in some areas it is very fertile, in others it is not.

Animals of the Rainforests

Tropical rainforests have a greater biodiversity than any other area of the Earth. There are a vast number of animals in the rainforests, with millions of species of insects, birds, reptiles, amphibians, and mammals, with insects being the most numerous.
 

Climate

There is very heavy rainfall for much of the year. Most rainforests have around 2 metres of rain each year, and the seasons are less noticeable than in other parts of the world. It never freezes in a tropical rainforest and the range of temperature is usually between 24-27° Centigrade.

The Soil in a Rainforest

The soil of a tropical rainforest is only about 8-10 centimetres thick, and tends to be poor as the rainfall leaches out the nutrients, but has been built up over millions of years. There is often thick clay beneath the soil. Once disturbed, the soil of a tropical rainforest takes many years to recover, if it is not irreparably damaged.

Plants of the rainforest

Some of the foods that were originally from rainforests around the world include oranges, grapefruit, lemons, limes, passion fruit, Macadamia, Brazil and cashew nuts, bananas, plantains, pineapple, cucumber, cocoa (chocolate), coffee, tea, avocados, papaya, guava, mango, cassava, tapioca, yams, sweet potato, okra, cinnamon, vanilla, nutmeg, mace, ginger, cayenne pepper, cloves,  peanuts, rice, sugar cane, and coconuts. There are also many plants in the rainforest which have medicinal value. For example, rain forests are responsible for containing ingredients of tranquilisers, stimulants, and birth control hormones.

People of the Tropical Rainforests

There are many groups of indigenous people who have live in the tropical rainforests. Many of these groups, like the Yanomami tribe of the Amazon rainforests of Brazil and southern Venezuela, have lived in scattered villages in the rainforests for hundreds or thousands of years. These tribes get their food, clothing, and housing mainly from materials they obtain in the forests. Forest people are mostly hunter-gatherers; they get their food by hunting for meat (and fishing for fish) and gathering edible plants, like starchy roots and fruit. Many also have small gardens in cleared areas of the forest. Since the soil in the rainforest is so poor, the garden areas must be moved after just a few years, and another part of the forest is cleared.

Most indigenous populations are declining. There are many reasons for this. Their primary problems are disease (like smallpox and measles, which were inadvertently introduced by Europeans) and governmental land seizure.

Temperate rainforests

Temperate rainforests are found along the Pacific coast of the USA and Canada (from northern California to Alaska), in New Zealand, Tasmania, Chile, Ireland, Scotland and Norway. They are less abundant than tropical rainforests. In a temperate rainforest, there are wet and dry seasons. During the "dry" season, coastal fog supplies abundant moisture to the forest. Temperate rainforests can be found in parts of the Balkans, the Caucasus, Alaska and Alaska.

Degradation of the rainforests

The biggest threat to the rainforest is man. The ever-expanding human population is exerting tremendous pressure on the resources and the space of the rainforest. Tropical and temperate rainforests have been subjected to heavy logging and agricultural clearance throughout the 20th Century, and the area covered by rainforests around the world is rapidly shrinking. It is estimated that the rainforest was reduced by about 58,000 km² annually in the 1990s.

Rainforests used to cover 14% of the Earth's surface. This percentage is now down to 6% and it is estimated by some that the remaining natural rainforests could disappear within 40 years (mid-21st century). Biologists have estimated that large numbers of species are being driven to extinction, possibly more than 50,000 a year, due to the removal of habitat with destruction of the rain forests.

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