The natural soil of the Amazon Rainforest is not too fertile but it is enriched by the vegetal covering made of leaves and branches that fall from the trees. Deforestation reduces this enrichment. In deforestation zones, the rain falls directly on the ground causing erosion, "washing" large areas (leaching) and contributing to make the soil even less fertile. Besides that, the deforestation disallows the recycling of essential nutrients for plants, like nitrogen. In this manner, those regions and their neighboring regions undergo desertification.

Image Diversity: Amazon Rainforest