The Amazon rainforest is the largest tropical rainforest on the planet. Its size is comparable to the continental United States, and covers more than half of Brazil's total landmass. It is located in the wide-reaching basin of the Amazon River, spanning over 2.7 million square miles of land from the Peruvian Andes to the Atlantic Ocean on the coast of Brazil.
Often referred to as the "lungs of our planet," the Amazon rainforest produces over 20 percent of the Earth's oxygen. Every species within it plays an integral role in balancing and maintaining the health of the forest. With such dense and tall-growing foliage, researchers have broken it up into four different layers--each boasting a unique ecosystem.
The highest layer is called the emergent layer. This layer can be as high as 200 feet from the ground. The emergent layer is exposed to most extreme elements, such as high winds and heavy rains. Some species find all they need to survive in this layer and rarely, if ever, leave.
The thickest layer is referred to as the canopy. This layer is extremely dense, filtering out about 80 percent of the sunlight to the two layers below. An almost entirely separate ecosystem flourishes here 100 or more feet off the ground, populated by an inestimable number of species of mammals, birds, insects and flowers.
The next layer is the understory. It receives very little sunlight and is therefore extremely shadowy and damp, making it the ideal place for mosses and ferns to thrive. There are a tremendous number of insects in the understory. Trees and flowers in this layer, because of the lack of wind and sunlight, depend on the many insects in this layer to pollinate their flowers.
Then there is the forest floor. The forest floor is extremely moist and porous as a result of the all the decomposing trees and plants that collect there. This layer receives almost no sunlight at all, and as a result produces no significant vegetation. The only activity happening on this layer is the multitude of insects feasting on the masses of decomposing material.
Over the past century, nearly 20 percent of the Amazon rainforest has been destroyed. Much of this deforestation is the result of mining, logging and cattle ranch operations. The other major factor has been the result of natives of the area clearing forest land for subsistence agriculture--often employing the "slash and burn" farming technique. Slash and burn farming involves cutting down areas of forest and then burning what has been felled. This is common practice in many tropical areas due the characteristically low nutrient levels in the soil. While these farming methods pose a significant risk to the future health of the Amazon, the much more dangerous factor is the increased industrialization of the area by the mining and logging industries. Without drastic conservation efforts, some scientists predict that most of the Amazon could be deforested in less than 40 years.
