Tropical rainforests cover nearly 7% of the Earth’s land surface1. There are four major biogeographical regions or ecozones in which rainforests are located: the Neotropical, the Afrotropical, the Australasian, and the Indomalayan.

Neotropical: This is the largest area of rainforest in the world1. It includes the rainforests of Mexico, South America, Central America and the Caribbean. It is this region that holds the greatest number of standing rainforests. The largest area of rainforest in this region is the Amazon rainforest, also known as the Amazon River Basin. The other two large rainforest regions include the Andes Mountains and the 30 miles of rainforest along the Atlantic coast of Brazil. Altogether, 1,678 million acres (679 million ha) remain in the Neotropical rainforests, about 58% of the world’s total rainforest1.

Afrotropical: The second largest expanse of rainforest is located in Africa. Most of Africa’s rainforests exist along the Congo River Basin, the world’s second largest river basin. This river basin contains the world’s second largest contiguous tropical rainforest, the Ituri Rainforest, in the Democratic Republic of Congo.1.  There are a few other rainforest along the coast of Western Africa, as well as the island on Madagascar. The African rainforests comprise about 20% of the world’s total rainforests.1

Australasian: Although Australia is known as the driest inhabited continent on the planet, the Australasian rainforests have expanded significantly in the last 18,000 years and remain nearly undivided. The largest portion of the Australasian rainforest is located in Papau New Guinea. It is often known as the last great expanse of rainforest. The Australian area of rainforest is known as the “Wet Tropics” and is located in the north-eastern part of Queensland.  The Wallace Line, the boundary that separates the ecozones of Asia and Australia, divides these rainforests from the Indomalayan rainforests.

Indomalayan: Some studies show that the rainforests in this region are some of the oldest in the world. These rainforests may have been in existence for over 100 million years. However, all of the remaining Asian rainforests are located in parts of Indonesia, the Malay Peninsula, Laos and Cambodia.

1Newman, Arnold. Tropical Rainforest: Our Most Valuable and Endangered Habitat with a Blueprint for Its Survival into the Third Millennium. New York, NY: Checkmark, 2002. Print

Scientists are able to estimate the number of stars in the sky better than they are able to estimate the number of species living in the tropical rainforest. Of the world’s estimated 5-10 million plant and animals species, tropical rainforests are home to half.1  Many of these types of species are endemic (unique) to one specific rainforest or to a specific area of one rainforest.  Primates are a great example of this, over 95% of are found only in rainforests and nowhere else in the world.1

Each of the world’s rainforests maintains different levels and types of biodiversity. While temperate rainforests are dominated by several types of trees, tropical rainforest species richness is such that there are more than 450 different species of trees in a 2.5 acres (or 1 hectare). Each of these trees provides a habitat that can host hundreds of species. For example, the rainforests in Peru contain more species of birds than the whole of the United States, one small pond in Brazil might be home to a larger variety of fish than all of the rivers in Europe combined, an in one tree in Brazil, there may be as many as 40-50 species of ants!1

There are many benefits to this kind of biodiversity. Currently, rainforest plants act as the basis for our modern day medicines. The National Cancer Institute has been performing research on these plants, and others, in order to find plant-based cures for cancer. Of the 3,000 plants identified as having elements that could potentially cure cancer, 70% are found only in the tropical rainforests. Developing our understanding of the vast number of species in the rainforest and their benefits is crucial to our improving quality of life. Of the estimated 5-10 million species in the tropical rainforest, only 6% have been discovered.1 Of that 6% only a tiny proportion (about one sixth) have been intensively studied.1 The rainforest is a resource with boundless possibilities but it must be protected in order for us to reap its benefits.

Bioiversity of the rainforest is also crucial to the resilience of  life of earth. In rare but catastrophic environmental events such as meteor impacts, or sustained volcanism, genetic diversity in the planetary gene pool is necessary for continuing life. The devastation of our rainforests and it’s impact was described by Harvard’s Pulitzer Prize-winning biologist, Edward O. Wilson, nearly 20 years ago. “The one process ongoing in the 1980’s that will take millions of years to correct is the loss of genetic and species diversity by the destruction of natural habitats. This is the folly that our descendants are least likely to forgive us for.”