By Kathryn Cannon
History of Tropical Rainforests
Tropical rainforests represents the oldest vegetative ecosystem still in existence. However, all vegetation, like that of the rainforest continues to evolve and change; so modern tropical rainforests are not identical with rainforests of the geologic past. They are a hot moist biome found near the Earth’s equator. The world’s largest tropical rainforests are in South America, Africa and Southeast Asia. Tropical rainforests tend to have fairly mild and/or warm climates and feature some of the highest levels of biodiversity around the globe. They are considered the “lungs of the Earth” because of the high amount of photosynthesis occurring in them. Rainforests once covered 14 percent of the earth’s land surface. Today, they only cover a mere 6 percent, and experts estimate that the last remaining rainforests could be consumed in less than 100 years. The tropical rainforests are a critical link in the ecological chains of our earth’s biosphere.
Current Status of Tropical Rainforests
More than half of the world’s estimated 10 million species of plants, animals and insects live in the tropical rainforests. They produce about 40 percent of the world’s oxygen. More than two-thirds of the world’s tropical rainforests left exist as fragmented remnants. The largest unbroken stretch of rainforest is found in the Amazon River Basin of South America. One-fifth of the world’s fresh water comes from here. Over half of this forest lies in Brazil, which holds about one-third of the world’s remaining tropical rainforests.
Currently 121 prescription drugs sold worldwide come from plant-derived sources; one in four comes from a plant in the tropical rainforests. The National Cancer Institute (NCI) estimates that 70 percent of the anti-cancer plants identified so far are rain forest plants. If we lose the remaining rainforests that we have, we may lose our only source to find cures for known and future diseases.
Deforestation of Rainforests
As people clear large areas of tropical forests, entire species are vanishing, many of them unknown. Experts estimate that we are losing a certain amount of plant, animal, and insect species every single day due to rainforest deforestation. With all the lushness and productivity that exist in tropical rainforests, it can be surprising to learn that tropical soils are actually very thin and poor in nutrients. Nearly all the nutrient content of a tropical forest is in the living plants and the decomposing litter on the forest floor. After the slash-and-burn method of deforestation, the nutrient reservoir is lost. Flooding and erosion rates are higher, and soils often become unable to support crops in just a few years. Therefore, farmers have to repeat the cycle continuously of cutting down more rainforests. Another concern with the slash-and-burn method is the amount of carbon dioxide released into the atmosphere. This contributes to the greenhouse warming effect.
Despite the increasing awareness of tropical deforestation, our knowledge is still very limited. Tropical rainforests have long been home to indigenous people who have shaped civilizations and cultures based on the environment in which they live. Logging, mining and farming in the rainforests sometimes displace indigenous communities. This has been known to lead to violence in some cases. Left without land or other resources, native cultures often disintegrate. The benefits do not outweigh the risk of deforestation for the temporary solution for having land to grow crops or to graze animals on.
The Future of Rain Forests
Nearly half of the world’s species of plants, animals, and microorganisms will be destroyed or severely threatened over the next quarter century due to rainforest deforestation. Our world is now facing the greatest extinction crisis since the fall of the dinosaurs 65 million years ago. The future of over 50 percent of Earth’s plants, animals and human cultures will be determined within the next few decades. Since our lives are so dependent on the forest’s bounty, our future is at stake as well. Our goal going forward needs to be on how to change the course we are currently on.