The Living World
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Biodiversity in Tropical Rainforests

Tropical Rainforests (TRFs) have the highest levels of biodiversity in the world. Although figures have not been confirmed, it is estimated that 50 to 80% of the world’s animal species are found within Tropical Rainforests.

There are many reasons for this:

  • Due to the wet and warm climate, there is almost constant growth in tropical rainforests. This means that there is a constant supply of plants and natural vegetation.
  • The near constant growth of flora contributes to biodiversity, which is why there are high levels of diversity within tropical rainforest plants and trees.
  • The constant nutrient cycling encourages and promotes plant growth.
  • For most of human history, humans haven’t interfered with Tropical Rainforests. Some indigenous peoples live there, but for many human populations, it’s a hostile environment to survive in.

Tropical rainforests have been used and valued by indigenous peoples for millennia. However, it was not until the 20th century that large-scale industrial exploitation of these ecosystems for resources such as timber, rubber and minerals became widespread. This was facilitated by advances in technology and infrastructure.

Adapting to Survive

Because of the extremely high levels of biodiversity, competition for resources is also high. Flora and Fauna have adapted over time to give themselves the best chances of gaining the upper hand over competitors.

The table below highlights some of these adaptations.

Lianas – Long, woody vines that are rooted in the ground but climb up trees to reach the sunlight in the canopy.Toucan – Possesses a long bill which allows it to cut fruit from weak branches. Toucans are also strong enough to break into nuts and fruits using their bill.
Tree Trunks – In TRFs trunks are tall and thin, prioritising upward growth over all else to reach the sunlight quickly. Bark is smooth on TRF trees, to allow water to run to the roots and to stop epiphytes from growing.
Stick Insects – Stick insects have evolved to resemble a stick at first glance. Insects are the food of many animals, so the stick insect’s camouflage is perfect to hide from predators.
Buttress Roots – Protruding, large roots that sit above the ground rather than under it. They help to support the large trees, as underground roots are too thin and weak.Poison Dart Frog – This frog contains a lethal amount of poison. The frog is brightly coloured to warn predators not to eat it, or they will face death.

Some frogs that aren’t poisonous adopt the same colourful pattern to ward off predators with the empty threat of poison.
Epiphytes – Plants that exist on the branches of trees in the canopy, receiving nutrients from the sun and water but not from the soil.

Although they do not take nutrients from the soil, they may gather nutrients from other sources like decomposing plant material, animal droppings and dust collected on tree branches.
Spider Monkeys – The spider monkey has adapted to live within the canopy, climbing through the trees of the rainforest. There’s less competition that high up and they’re safer from predators who can’t climb as high.
Drip Tips – Leaves on plants have adapted to have pointy tips. This adaptation lets the water run off the leaf quickly, without damaging the leaf in the process.

The purpose of this adaptation is not only to prevent damage to the leaf, but also to avoid the growth of fungus and bacteria that thrive on wet surfaces.

The adaptations listed for both plants and animals have evolved specifically to deal with the unique challenges of life in a tropical rainforest.

The biodiversity of Tropical Rainforests is important for the functioning of these ecosystems. Read more about the interdependency of TRFs here.

Key Terms

BiodiversityThe variety of plant and animal life in a particular ecosystem or area.
FloraThe plant life of a particular region or time, usually used in conjunction with fauna meaning animals. 
Nutrient CyclingCyclical process that moves nutrients from the physical environment to living organisms and back to the environment. 
CanopyThe second highest level of the rainforest, after the emergent layer. It receives a lot of sunlight and is a site of intense competition for light and space among the trees and plants. The canopy is crucial for the rainforest’s climate regulation and serves as a habitat for a diverse range of wildlife.

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