Tropical rainforests are known for their biodiversity. These areas have abundant plant species and are teeming with animal life. Why are tropical regions so rich in biological organisms? Some scientists hypothesize that it is due to the excessive amount of rain and sunlight that are concentrated in the tropics allowing for lush plant growth which in turn supports many animal species. Another factor is the age of these environments. Some tropical rainforests have endured for millions of years. This has allowed time for many of organisms to evolve. Tropical species were not wiped out by the glacial periods as in many temperate regions so they have had more time to diversify.
Many of the rainforests of the world are classified as biodiversity hotspots. To qualify as a hotspot as defined by Conservation International, a region must meet two strict criteria: it must contain at least 1,500 species of endemic vascular plants (> 0.5 percent of the world’s total), and must have lost at least 70 percent of its original habitat. Hotspots include areas in Coast Rica (part of the Mesoamerica hotspot), Madagascar, and Borneo (part of the Sundaland hotspot). These biodiversity hotspots are species rich. And because they are threatened, they are in need of extensive conservation efforts to protect the remarkable organisms that live there.
The principle threats facing rainforests around the world include habitat loss, climate change, hunting, pollution, and the illegal pet trade. All of these destructive activities are human induced. There is a complex and unique balance that exists in rainforest ecosystems and human activities can disrupt this balance. For example, hunting can be done in a way that does not distroy the rainforest ecosystem if it is done on a small scale and does not persist in the same area over a long period of time, thus killing most or all of a particular type of animal. Tribal people living within the tropical rainforest have been hunting for food for thousands of years with minimal impact on the balance. However, many non-indigenous people have moved into and utilize rainforest habitat and exert hunting pressures on the rainforest that are not sustainable and throw the fragile ecosystem out of balance.
Climate change is affecting the climate and weather of different locations all over the world and causes changes in species distributions. One observable pattern is that many species’ ranges are moving up in elevations on mountainsides because they can no longer live in the lower elevations due to the increased temperatures. It is not certain how climate change will affect tropical rainforests overall, but climate change effects coupled with habitat destruction will likely worsen an already dire situation. Burning rainforest trees creates two problems- the burning releases more CO², a gas that contributes to global warming, and the burned trees are no longer available to take in CO² and release O². Changes in tropical rainforests are altering the atmosphere, perhaps even affecting the hydrologic cycle.
Habitat loss is the greatest threat facing most tropical rainforests. This is occurring due to the large scale development of natural areas to meet human’s need for logging, agriculture, building roads or towns, mining, and making grazing lands for cattle. Loss of habitat is a serious threat that wreaks havoc on the fragile natural systems that support such an abundance of life. On the island of Borneo, for example, in the past 20 years, 80 percent of the island’s rainforests have been lost to illegal logging, new plantations, gold mining and fires. These types of resource extraction also release pollution into the environment which can affect surrounding areas that still have intact rainforest habitat.
The illegal pet trade has been an increasing problem for tropical rainforest species. The wildlife trade is regulated by agreements under the Convention on International Trade in Endangered Species (CITES), a 172-member international organization of which the United States is a member. Virtually every wild animal that enters the U.S. must be accompanied by a correct CITES permit and supporting paperwork from the exporting nation. Unfortunately, many people break these rules. A great number of animals are smuggled into the United States every year and sold for large sums of money. Many species of monkeys, snakes, frogs, and birds are threatened by this black market.
Unfortunately, the loss of rainforests means the loss of species. Many of the species that are going extinct right now have never even been studied and described by scientists. Knowledge of species is an extremely important part of scientific understanding of the natural world as well as developing new products such as medicine that can be of great benefit to humans. Because rainforests are so diverse and so threatened, we need to rapidly collect more information about rainforest organisms in order to know what life forms exist before they are lost. At the same time we must make great conservation efforts to preserve these lands and protect ecosystems that are crucially important to the survival of rainforest species and to our own survival.