Indiscriminate felling of forests is one of the human practices with the worst impacts for agriculture and the entire biosphere, although the severity of the consequences varies with the kind of soil and the climate of the area. In the slopes, it is the main cause of erosion, which involves an elevation of riverbeds because of the accumulated dragged material, blocking the bed and causing floods followed by droughts.

Swamps are also filled with earth and stones, shortening the lifespan of dams. The same happens in estuaries, where new islands are formed with the sediment dragged that gradually reduces fish catch. Damages produced on flora and fauna added to these environmental impacts are irreparable when dealing with millenary forests with abundant endemic species incapable of reproducing themselves in the new conditions after the felling. To date, 50% of tropical forests have been deforested in America, 85% in Africa and 75% in Asia.

The effects of deforestation are especially dramatic in tropical forests, because of the fragility of these ecosystems. Among the reasons for this deforestation, there are two particularly decisive: the exploitation of tropical fine wood, that have a great demand in the furniture industry in industrialized countries, and the need of the local population to increase crop lands and pasture lands for the cattle.

In any case, once the soil of a tropical forest loses its trees, it suffers great erosion because of torrential rains and the heavy sun, becoming a desert very easily, not only because of the loss of nutrients and humus caused by quick oxidation, but also because of felling produces more dryness of the atmosphere. In tropical areas, rainfall is mainly produced by the vegetation itself. 
Nowadays, the land is exploited until the total destruction of the soil.

In such conditions tropical soils, rich in ferruginous materials, suffer a process called laterizaton in the long run. This process consists in the formation of a very hard crust in the surface where nothing can be grown and that will not retain water. At this point, the soil needs millions of years to recove