Dense vegetation, the remnants of the rainforest, show up red in this infrared satellite image of deforested areas in the Amazon basin of Brazil. The geometrical shapes are areas of cleared land. In 1970, about 99 per cent of the Amazon rainforest was still standing; 30 years later, only 85 per cent remained. The main cause of deforestation here is slash-and-burn clearance for agriculture. Rainforest soils are usually poor in nutrients and can only be farmed for a few years before more clearance is necessary.