Damage from deforestation

Very large areas of tropical rain forest are currently being disturbed by human activities. This is of great concern because the forests are so rich in plant species and fauna. It has been estimated that they contain over 50 per cent of the known plants and animals in the world yet they occupy less than 10 per cent of the land area of the world. The biggest threat comes from deforestation which is going on at a considerable rate. Not only does this remove the habitat of some of the world's most wonderful plants and animals but it seriously damages the soils, the lifeblood of the rainforest. It affects the soil in two main ways.

Firstly is the loss of the organic topsoil in the process of deforestation. This is the store of vital nutrients for the plants that grow. The organic layer itself is a fragile entity that once exposed to the rigours of the tropical rainfall, will be readily washed away. Fertility will decline rapidly and whatever future use is to be made of the soil will require huge replenishment of the nutrients. Soil erosion is the other significant damage due to deforestation. Once the protective cover of forest is removed the soil will be exposed to the heavy incoming rainfall. The organic matter layer is thin and fragile and the soil beneath is usually poorly structured. The rainfall in the tropics is both high and torrential, and this falling on an unprotected soil, leads to extensive and advanced soil erosion.

The large scale loss of topsoil by erosion diminishes the potential and fertility of the soils. Damage is not limited to the immediate area of logging but can affect the wider region with gully formation, silting up of dams, etc.. Logging can lead to artificial roads being creating which become the channels for runoff of rainwater and become themselves the focus for much erosion. Once the land has been deforested, the soils have often been further impoverished and may be of very limited use for the purposes for which they are intended, such as plantation agricultureThe clearing of the tropical rainforest, which usually involves burning part of the vegetation, has also been linked with global climate change. The clearing and burning of the dense forest and the loss of soil organic matter, which together contain huge amounts of carbon, is considered to have caused a significant increase in the release of CO₂ to the atmosphere. It is considered by many to be an important contributory factor to global warming.