Deforestation is the removal of vegetation such as trees, plants and shrubs from the surface of rainforests. Deforestation occurs mainly for logging purposes and to provide land for agriculture, ranching and road construction. Soil erosion is a major consequence of deforestation, as it reduces soil stability and exposes soil to harsh environmental factors such as rain and wind.
Soil erosion, a natural occurrence that has been documented for many centuries, is drastically exacerbated by human activity. Between 1950 and 1990, approximately 20 per cent of the world's topsoil was lost to soil erosion. Deforestation is a direct contributor to this, an example being Brazil, which is estimated to lose 55 million tons of top soil annually due to deforestation.
Soil from deforested areas is heavily affected by rainfall and strong winds as the lack of vegetative cover increases exposure. In addition to absorbing excess water, tree roots bind soil together, preventing soil from washing away after heavy rainfalls, particularly on hillsides and near riverbanks. Trees also act as wind breakers, reducing the amount of topsoil blown away by heavy winds.
Consequences of Soil Erosion
Rain-eroded soil from deforested areas usually ends up as sediment in rivers and lakesm, causing downstream flooding. In cases where topsoil contains fertilisers, erosion can contaminate drinking water sources and damage aquatic habitats. Wind-eroded soil contributes to air pollution and can sandblast nearby crops and buildings. Areas that experience severe topsoil depletion eventually suffer from desertification.
Limiting Soil Erosion
Approximately 1.25 billion hectares of degraded land can be restored but with considerable effort--mainly involving adequate reforestation to protect soil from adverse weather conditions. This includes strategically planted wind-breaking trees, hedges and tall grass as well as reforesting hillsides and riverbanks.