The results of slash-and-burn are devastating and long term. In "slash-and-burn" a plot of tropical rainforest is cut down and the vegetation is left to die. What is left is then burned, and the plot is turned into farmland. Initially, the ash that is left has a high nutrient level, but within only a few years the soil becomes very poor. This depletion in nutrients is partially do to an increase in erosion. The roots of trees in tropical rainforests keep erosion to a minimum. Without these trees, the soil is quickly washed away by rain which falls in large amounts in areas of tropical rainforest. An 2.47 acre (1 ha) plot of rainforest may experience a loss of about 1 ton of soil due to erosion in a year. Once the trees have been cleared and converted into farmland, 20-160 tons of soil may be lost in a year. Another reason for the depletion of nutrients is a decrease in natural fertilizer. In the tropical rainforests, falling leaves, fruit, and other organic materials are quickly decomposed and absorbed by the plants of the rainforest. Without the debris of trees or the plant and animal life that accompanies them, the nutrients of the soil cannot be replenished.

   Slash-and-burn is destructive and requires hundreds of man hours for a single plot. Migrant families that live off of the farmland of these plots have to move on once the soil has been depleted, which occurs within 5 years normally. Aborigines also practice slash-and-burn, but they allow long periods of time for the plot to recover. However in areas of overpopulation where land is limited, the process of slash-and-burn is often repeated in the same spot, before the rainforest and its soil has fully recovered. Some estimates say that at this rate of destruction, in 40 years there will be no more rainforests





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