The World Wildlife Fund (WWF) defines biodiversity as "the wealth of life on Earth, the millions of plants, animals, and micro-organisms, the gens they contain and the intricate ecosystems they build into the living enviroment." Rainforest are one of the most biologically diverse regions of the world. Over a millions species of plants and animals are known to live in the forests and millions more are not classified. The unique enviroment of the rainforest allows for such biodiversity to exist.
The process of deforestation in various geographical regions is destroying this unique enviroment. Consequently, many animals and plants that live in the rainforests face the specter of extinction. The extinction of the plants and animals leads to diminished gene pool. The lack of biodiversity and a reduced planetary gene pool could have many unforeseen ramifications, some of which could be fatal to the future of humanity. In addition, there are ethical, aesthetic and philosophical question regarding mankind's responsibility for other life. This issue concerns more industrialized countries in the North more than it concerns lesser developed countries in the South. This is especially true in developing countries such as Brazil. I will elaborate on that later.
Another isssue that probably concerns the North more that the South is the advancement of humanity. As the planetary gene pool continues to diminish, there are less oppertunities for advancements in many fields. In particular, medicine may benefit from the cultivation of certain plants that grow only in rainforests. The medicines that come from them could cure cancer, AIDS, or other terminal deseases. Of course, that claim can easily be dismissed as speculative, given that there is little or no evidence to support it. However, it is too early to dismiss the possibility. Furthermore, if the rainforests are completely destroyed, the oppertunity to explore that possibility would be lost forever. The effect that would have on future generations is incalculable. Preserving the rainforest would leave many oppertunities in medicine and many other fields open for future generations to explore and further advance humanity.
There is at least on issue that would concern both North and South equally. That is preservation and is compatibility with forest use and management. Different people have different uses of rainforests. Indigenous people who live in the forests, as well as the non-indigenous people who live in the forests, the forest is their home, source of food, shelter, nourishment, recreation, culture, and livelihood. The forest provides the materials for thier homes, wood for their fires, the fish, the edible plants, and many more neccessities as well as amenities. Some of the non-indigenous people sell some of the forest resources for money. They do not exploit the forest because they sell commodities in limited numbers to preserve the forest resources for the future. This ensures that they can continue to make thier livelihoods by selling products from the forest.