GCSE Geography | What are Tropical Rainforests Like? (Tropical Rainforests 1)

Tropical rainforests lie along the Equator, in South America, Central Africa, South-east Asia and North-east Australia. They cover approximately 6% of the world's land surface. The largest area of rainforest is the Amazon Basin, which covers Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Suriname, and French Guiana.

Layers of the rainforest

There are four distinctive layers in the tropical rainforest.

• Emergents - these are the tallest trees in the rainforest, with some over 50m in height. The trees have grown tall here to reach the sun, and are home to species of birds, such as parrots and toucans, along with bats.
• Canopy - this is the most dense part of the rainforest and is home to the most species. Trees can grow to 30m in height, and receive high levels of sunlight.
• Under canopy - this is a lower level of trees that grow to around 15m in height, due to the canopy above this layer only receives around 10% of the sunlight in the rainforest. This part of the rainforest is very damp so species of frogs and snakes thrive here.
• Forest floor - this layer is very dark and is covered in leaf litter. It is home to large predators, such as jaguars.
  

Rainforest climate

Tropical rainforests are located on or close to the Equator, so they are warm and wet all year round with little daily or seasonal variation. Temperatures are around 27 degrees on average, and annual precipitation usually exceeds 2,500mm (compared with between 800-1,400mm in the UK). The high level of rainfall means that a huge amount of water feeds the enormous rivers that often run through rainforests, such as the Amazon in South America and the Congo in Central Africa.

Rainforest vegetation

Tropical rainforests have dense lush vegetation and very tall trees. Plants in the rainforests have specific adaptations that enable to them to compete for sunlight and nutrients, and survive, in the warm and wet conditions (see separate notes on this).

Plant growth is rapid because the hot and humid conditions speed up the nutrient cycle making ideal conditions for plants. The canopy also receives plenty of sunlight to absorb for photosynthesis, which is why the vegetation is so dense in this layer.

Rainforest soils

Despite the rich vegetation found in tropical rainforests, the soils are thin and poor, so are not very fertile. The vegetation is so luxuriant because of nutrient cycling - between biomass (living organisms), leaf litter (dead wood and leaves, and animal remains) and the soil. Leaf litter decomposes rapidly because of the humidity in the tropical rainforest, however the nutrients released are often washed away by the heavy rainfall, a process known as leaching, before becoming part of the soil.

Biodiversity

Tropical rainforests have high levels of biodiversity - home to more than two-thirds of global plants species, and over half of the world's animals, including mammals such a many species of monkey, birds such as parrots and toucans, reptiles such as lizards, amphibians such as tree frogs, and countless insects.