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Tropical rainforests have distinct characteristics that support a wide variety of different species. This means that they have a high biodiversity. The biotic or living components of the ecosystem and the abiotic or non-living components of the ecosystem depend on one another - a change in one leads to a change in the other.

Climate

• Very wet with over 2,000 mm of rainfall per year.
• Very warm with an average daily temperature of 28°C. The temperature never drops below 20°C and rarely exceeds 35°C.
• The atmosphere is hot and humid.
• The climate is consistent all year round. There are no seasons.

Soil

• Most of the soil is not very fertile.
• A thin layer of fertile soil is found at the surface where the dead leaves decompose.
• It is red in colour because it is rich in iron.
• Due to heavy rainfall the nutrients are quickly washed out of the soil.

Plants and animals

• The warm and very wet climate provides perfect conditions for plant growth.
• The wide range of plant species supports many different animals, birds and insects.
• Species have adapted to the conditions of the rainforest, eg trees and plants have shallow-reaching roots to absorb nutrients from the fertile top layer of soil.

Structure of a tropical rainforest

A tropical rainforest is made up of the following layers:

• Ground level - contains less vegetation due to the dark, damp conditions, a thick layer of decomposing leaves and buttress roots of trees.
• Shrub layer - dense and dark with small plants.
• Under canopy - contains younger trees and saplings competing for light in dark conditions.
• (Main) canopy - the 'roof' of the forest. Contains tall trees, climbing plants like vines and lianas. 50% of rainforest life is found here.
• Emergent - contains the tallest trees emerging out of canopy.