There are many causes, ranging from slow forest degradation to sudden and catastrophic clear cutting, slash-and-burn, urban development, acid rain, and wildfires. Deforestation can be the result of the deliberate removal of forest cover for agriculture or urban development, or it can be a consequence of grazing animals, primarily for agriculture. In addition to the direct effects brought about by forest removal, indirect effects caused by edge effects and habitat fragmentation can greatly magnify the effects of deforestation.
One-fifth of the world’s tropical rainforest was destroyed between 1960 and 1990. Estimates of deforestation of tropical forest for the 1990s range from about 55,630 to 120,000 square kilometres each year at this rate, all tropical forests may be gone by the year 2090.