Rainforest Basics


Rainforests are clustered around the equator (Central and South America, Africa, South Asia and Australia) and occur on the 7% of the dry land surface of the planet where it is both warm enough and wet enough. There are temperate rainforests such as in the Olympic peninsula, but without tropical temperatures they have much lower biological diversity. Rainforests require a minimum of 100 inches of rain a year. They normally have dry seasons but require moisture even in the drier months. In contrast, a New England forest receives about 40 inches of rain a year and the Arizona desert 7 inches.

Rain forest trees are about 100 feet tall, but there are taller trees known as “emergents” that can easily reach an additional 30 feet above the canopy. The forest is also very stratified with different animals and plants living at different levels. Virtually the only species the canopy and the rainforest floor share in common are the trees themselves. The birds of the rainforest canopy are a completely different set of species from those at lower levels. The canopy is in brilliant sunlight during the day, but it is dark (almost gloomy) at the rain forest floor, where only one to two percent of light reaches.

The Rainforest Crisis

Critical Rainforest

More than half of the original tropical forest is gone, and in some places like the Atlantic forest of Brazil or Madagascar only a few percent remains. Much of the lowland forest in Indonesia and Malaysia is gone as well.

Each of these areas represents a "biodiversity hotspot" where there is a concentration of species that occur nowhere else and are under severe threat. In many instances there has been little gain in human welfare as a result of the deforestation; in fact it further impoverishes already poor people.

The extinction of a large number of plant and animal species looms if the trends are not stopped and reforestation instituted. As a consequence of the Convention on Biological Diversity, many rainforest countries now have active programs in rainforest protection; rainforest protected areas and indigenous areas that protect native peoples and their forests have made significant progress.

There are major conservation programs in the Amazon (ARPA: the Amazon Region Protected Area project) and in the Congo Basin, the former with World Bank assistance and the latter with US AID. Much more needs to be done.