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Chapter summary

  • A tropical rainforest has four distinct layers: the emergent layer, the canopy, the understorey and the forest floor.
  • The rivers and streams in a rainforest can also be considered one of the structural features.
  • The climate of a rainforest is one of its main features. This climate includes the rain, humidity and temperature.
  • A rainforest does not have seasons as we know them, it only has a wet season and a dry season.
  • A tropical rainforest is evergreen, which means that the leaves on the trees never fall off.

Introduction

The most basic features of a rainforest are those that make up its unique structure. These layers are important and interesting because they contribute to the delicate balance of life that exists in the rainforest. Each level is home to different plants and animals uniquely suited to the environment.

Emergent layer

The trees that make up this layer are the tallest trees in a rainforest. There are not many of these trees, only one or two per hectare. The trees in this level have several clear advantages: they receive the most sunlight and they have lots of room to spread out. These giants of the rainforest can grow to over 50 metres in height.

The canopy

This layer is the thick branches and leaves of the taller trees. These can grow to heights of 40 to 45 metres. This layer is somewhat like a roof. The coverage is so dense that it blocks out 98 percent of sunlight. It is in this layer that most of the animals of the forest make their home (approximately 90 percent). There is plenty of food in this layer, it is sheltered and the height provides protection from some predators. This layer stops 80 percent of the yearly rainfall.

The understorey

This layer is between the canopy, which forms the 'roof', and the forest floor. The understorey is made up of tall shrubs and smaller trees, less than 10 metres in height. Because this layer is dark and hot, many varieties of moss and algae flourish here, as they need very little sunlight and like the damp environment. Ferns, palms and climbing vines also flourish at this level.

The forest floor

The forest floor is a carpet of dead organic matter. Little to no sunlight reaches the forest floor. It is a perfect habitat for many insects and other organisms. The conditions are best suited to fungi, which thrives on the forest floor. This is also an ideal hunting ground for predators that can hide and await their prey. The conditions at this level allow leaves that fall from the trees to decompose rapidly. The trees then absorb the nutrients provided by the decomposed leaves.

Rivers

When listing the layers (strata) of a rainforest, another level is often included. This level is the rivers. The rainforest has many rivers and streams flowing through it. These are inhabited by reptiles and amphibians. The rivers and streams are a damp, warm and sunny area of the forest.

A rainforest also has a number of other distinct features which are necessary for it to function, and which are the result of the way the rainforest functions.

Humidity

A rainforest has an almost constant year-round humidity. This is because a rainforest receives lots of rain and has a constantly warm temperature.

Temperature

The temperature of a tropical rainforest must range from 21oC to 27oC throughout the year.

Rain

A rainforest receives at least 200cm of rain a year. The tallest trees of the forest have long leaves that allow the rain to run off.

Seasons

As a result of the consistent temperatures and humidity and the constant yearly rainfall, a rainforest only has two seasons. Tropical rainforests have a wet season and a dry season. Temperate rainforests have a long, wet winter, and a shorter, drier summer.  

Evergreen

A tropical rainforest is evergreen. This means that the leaves on the trees do not change colour and they do not fall from the tree.






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Question 1/5

1. The layer that provides an ideal hunting ground for predators is

the understorey.

the emergent layer.

the canopy.

the forest floor.

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