Geography

The layers are a quite distinct feature that are found only in rainforests because of the low light conditions. Most forests have more light and layers are not discernible because all the vegetation grows at different levels.

The canopy is the dominant and most noticeable layer of the rainforest. It is created by all the trees competing for light so that they all grow to the same height and their leaves and branches are arrange to obtain as much light as possible. This creates a solid ceiling, with the forest of branches and leaves blocking out up to 70% of the available light. The canopy is normally about 20 to 30 metres above the floor of the forest and plays an important role in keeping the rainforest moist and cool because it cuts out much of the sunlight. In addition it protects the forest from dry winds and sudden changes in temperature. The canopy also provides a ready supply of moisture for evapotranspiration to help condensation and rainfall, whilst it absorbs much of the rainfall before it reaches the ground, stopping the rainforest soil from losing all its nutrients.

The canopy can be considered the richest and most biodiverse part of the rainforest, with most of the forest's animal species living in it. This includes reptiles like frogs and insects.

Above the canopy is another layer called the emergents, which is less important than the canopy in maintaining rainforest conditions but which provides a habitat for some species, particularly birds. While the canopy protects its animal inhabitants from windy conditions, the animals living in the emergents are subject to very windy conditions, with the trees that form the layer sticking out of the canopy at 30-40 metres high. These trees do this because it gives them more access to sunlight.

Below the emergents and the canopy is the sub-canopy or middle layer of the rainforest which contains trees that are growing towards the canopy, as well as some epiphytes and vines. This layer is more obvious in warm temperate rainforest than subtropical rainforest because warm temperate rainforest has more sunlight filtering through the canopy, allowing trees to grow more easily below the canopy.

The final layer is the forest floor which is dominated by shade-tolerant species such as ferns, mosses and fungi. This layer of the rainforest receives the least light and as a result has fewer plant species, but the organic matter lying on top of the soil and the soil itself are teeming with animals which live off and help process the organic matter into the soil, for reuse by the huge trees of the canopy.