Tropical Rainforest (Edexcel GCSE Geography B)

Tropical Rainforest Characteristics & Adaptations

• All parts of the tropical rainforest (TRF) ecosystem are interdependent

  • A change in one part affects others

  • Deforestation leads to the loss of habitats and reduction in biodiversity

  • Loss of trees also impacts the nutrient cycle

• The interdependence of the rainforest components means that when one element is affected it then impacts all the other components

• A decline in one species (especially if it is a keystone species) can lead to a decline in other species 

  • The Zam tree produces seeds which are food for agouti and who disperse the seeds 

  • The agouti is hunted for meat, reducing their populations, which means fewer seeds are dispersed

  • Fewer new Zam trees will germinate and so there is less food for leaf cutter ants, which in turn means less food for the tree frogs and the snakes which prey on the frogs

  • The Zam tree is pollinated by a particular species of butterfly. Without the flowers the numbers of the butterfly species will decline: this also affects the beetles which lay their eggs in the butterfly faeces

• Plant and animal species may become extinct: this may happen to some before they are even discovered

• Important medicinal plants may become extinct

• Indigenous communities may be forced to abandon their traditional lifestyle due to the lack of food to hunt and gather

Structure of the tropical rainforest (TRF)

• The TRF has five distinct layers

  • Ground layer (0m)

  • Shrub layer (3-4m)

  • Under canopy (15m)

  • Canopy (30m)

  • Emergents (45-55m)

Adaptations

• The plants and animals within the tropical rainforest are very well adapted to the climate conditions

Adaptations of Plants and Animals in a TRF

• TRFs have some of the highest levels of biodiversity of any ecosystem

  • The wet and warm climate means there is year round growth 

  • Wide variety of plants provides a range of habitats and food 

  • Rapid nutrient cycling increases plant growth

  • Lack of human activity in the past has meant that plants and animals are undisturbed 

Tropical Rainforest Nutrient Recycling

Nutrient cycle

• TRFs have a continual growing season with high rainfall and temperatures all year round

• The nutrient cycle is rapid

  • Trees and plants lose their leaves all year round

  • The high level of moisture and high temperatures leads to rapid decomposition and recycling of nutrients

  • Plants grow quickly which leads to a rapid uptake of nutrients from the soil

• Most of the nutrients are stored in the biomass

• Few nutrients are stored in the soil and the litter

• The result of this rapid nutrient cycle is that the soil in the TRF is not very fertile

• Net Primary Productivity (NPP) is higher in the rainforest

Food web

• As in all ecosystems the TRF has a complex food web which includes

  • Producers

  • Primary consumers

  • Secondary consumers

  • Tertiary consumers