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Geography

Tropical rainforests

Rainforest water and nutrient cycles

Rainforest ecosystems are characterised by heavy convectional rainfall [convectional rainfall: Occurs in warm or tropical climates when heated air rises and cools. ], high humidity [humidity: The amount of water vapour in the atmosphere measured as a percentage. ], lushness of vegetation and nutrient-rich but shallow soil. These factors give rise to a unique water and nutrient cycle [nutrient cycle: How the minerals that provide energy and sustenance to living organisms circulate around an ecosystem. ].

Rainforest nutrient and water cycle

Rainforest nutrient and water cycle

Rainforest water cycle

The roots of plants take up water from the ground and the rain is intercepted as it falls - much of it at the canopy level. As the rainforest heats up, the water evaporates into the atmosphere and forms clouds to make the next day's rain. This is convectional rainfall.

Rainforest nutrient cycle

The rainforest nutrient cycling is rapid. The hot, damp conditions on the forest floor allow for the rapid decomposition of dead plant material. This provides plentiful nutrients that are easily absorbed by plant roots. However, as these nutrients [nutrient: A substance that provides energy and sustenance to living organisms. ] are in high demand from the rainforest's many fast-growing plants, they do not remain in the soil for long and stay close to the surface of the soil. If vegetation is removed, the soils quickly become infertile and vulnerable to erosion.

If the rainforest is cleared for agriculture it will not make very good farmland, as the soil will not be rich in nutrients.

Rainforest soils

Watch

Images and sounds of a tropical rainforest biome.

Soils are red due to the high iron and aluminium content. There is a thick layer of leaf litter and decomposing organic matter on the surface.

Back to Ecosystems - the living world index

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