Only the top few inches of the rainforest soil has any nutrients. Most of the nutrients are in the biomass, the bulk of animal and plant life above the ground. As water evaporates in the forest it forms clouds above the canopy that later fall as rain. They help control the world's climate. However, when the rainforests are burned and cleared, carbon is released that causes the weather to be much hotter.
People also use many rainforest materials.
Many of our medicines come from plants that grow in rainforests. Perhaps someday the cure for cancer or AIDS will be found in a tropical rainforest. Some of the medicines we now use come from tropical rainforest plants, such as aspirin, heart disease treatment and painkillers. Logging for tropical timber and gold mining have contributed to much of the destruction of tropical rainforests. They use every part of the forest in a sustainable manner, or in a way that does not destroy the forest.