AQA Geography A2 Ecosystems Case Studies Part 3

Tropical rainforest

The Tropical Rainforest is a forest occurring in tropical areas of heavy rainfall. It is abundant with many species of wildlife and vegetation. Rainforests cover less than two percent of the Earth's surface. They are home to some 50 to 70 percent of all life forms on our planet. Rainforests are the most productive and most complex ecosystems on Earth.

Distribution

Tropical rainforests are located around the equator where temperatures stay near 80 degrees year round. Rainforests receive 50 to 260 inches (125 to 600 centimetres) of rain each year. The largest rainforests are in Brazil (South America), Zaire (Africa) and Indonesia (South East Asia). Other tropical rainforest places are in Hawaii and the islands of the Pacific & Caribbean.

Structure

Emergent layer

These are the trees which are over 50 meters tall and stand out from the canopy layer an example of this is the Kapok tree. These trees also have thick trunks so they can support the weight of the tree. These plants get the most sunlight and so grow the most.

Canopy layer

These have a height of 30 to 40 meters; the canopy contains over 50 percentage of the rainforest wildlife. This includes birds, snakes and monkeys. Lianas (vines) climb to the canopy to reach this sun light. An example is the Cacao Tree

Small trees/ saplings layer (understory)

This is the layer directly beneath the canopy layer were the smaller trees and saplings are these get limited sunlight due to the dense canopy above it so the plants here do not grow as fast. These tend to have a height of 20 to 30 meters. An example of this is Dipoterocarp tree

Shrub layer

The shrub layer has the densest plant growth. It contains shrubs and ferns and other plants needing less light. Saplings of emergent and canopy trees can also be found here. These have a height of 10 to 20 meters. An example of a of a shrub is Bougainvillea

Herb layer

The forest floor is usually dark and damp. It contains a layer of rotting leaves and dead animals called litter. This decomposes rapidly (within 6 weeks) to form a thin humus, rich in nutrients. These are the plants below 10 meters. An example of this is Jambu

Climate

In an average year in a tropical rain forest, the climate is very humid because of all the rainfall, which amounts to about 450 centimetre per year. The rain forest has lots of rain because it is very hot and wet. This climate is found near the equator. That means that there is more direct sunlight hitting the land and sea there than anywhere else. The sun warms the land and sea and the water evaporates into the air. The warm air can hold a lot of water vapour. As the air rises, it cools. That means it can hold less water vapour. Then as warm meets cold, condensation takes place and the vapour forms droplets, and clouds form. The clouds…