The loss of biodiversity due to deforestation has brought a negative impact to the ecosystem of rainforests. Gradually, as rainforests lose biodiversity, many species that provide valuable and unique roles to the ecosystem are wiped out. For example, humans derive most of their essential nutrition through food from animals and plants in rainforests. A loss of biodiversity means that humans are losing animals that could serve as biocontrol agents and plants that could potentially provide crop varieties. Furthermore, humans are losing potential sources for drugs that could cure existing or future diseases such as cancer. In many parts of the world, forest areas covered with colourful flowers provide visual enjoyment to visitors and rare forest sceneries support tourist industries. A typical example is Namaqualand in South America that used to attract more than 2000 visitors each spring, representing a huge source of income for regional economies. (rainforests, N/A) However due to the grdual destruction of the ecosystem and the consequent loss of flowers, plants, trees and even animals has affected tourism. The forest no longer receives the same popularity as a tourist site.
Hydroelectric power is another cause of the biodiversity loss due to deforestation in tropical rainforests. There is an unlimited supply of water and ideal river condition in rainforest areas, which encourages the development of hydroelectric power stations. Hydroelectric power has provided people with great amounts electricity power and stimulated the industrial development of both urban and rural areas. However such power stations significantly contribute to the loss of biodiversity in rainforests due to the immense flooding caused by hydroelectric power dams. For example, the Tucurui Dam in Brazil takes up a massive area of 2875 square kilometers. Building the dam not only imposed a threat upon numerous trees that had to be cut down, but also flooded 2500 square kilometers of the Amazon forest due to the flatness of the basin, killing off countless of wild lives. The diversity of species reduced from 164 to 133, a 19% decline due to poor water quality. (news.mongabay, 29th January 2009)
As a result of above, the loss of plants and trees in rainforests also causes widespread soil erosion throughout the tropics. Tropical rainforests are stereotyped to be lush and full, but their underlying soils however are very poor. Once there are insufficient tall trees and plants to cover the soils, eventually the rare areas with good soil will be washed away with the heavy rain. As essential nutrients in the soils of tropical rainforests are washed out, soil erosion happens. This is the case in Costa Rica, as it loses approximately 860 million tons of nutrient soil every year due to soil erosion caused by deforestation. Moreover, the Great Red Island of Madagascar loses so much soil to erosion, 400 tons per year, that its rivers run blood-red, polluting the surrounding Indian Ocean. (wikipedia, 4th November 2010) If various trees and plants were preserved, they could continue protecting the good soil from heavy rain, and prevent environmental damage in world-wide rainforests caused by soil erosion.
Human migration is the third factor causing biodiversity loss amongst tropical rainforests. The growth in the global population encourages countryside people to migrate to forest land areas, because living in urban areas is costly and at the same time forest land is extremely cheap. As living in forest land has widely encouraged many landless immigrants, trees in rainforests have to be cut down in order to make space for the people to live in. The case is the most serious in developing countries around the world such as Latin America, where migration is the primary proximate cause of loss of biodiversity due to forest clearing. Every year, 60 thousand square kilometers of land is cleared due to human migration in the forests of Latin America. This is equivalent to cutting down 6 billion trees. (eoearth, 6th November 2010)
As another consequence, biodiversity loss due to deforestation also significantly increases the carbon dioxide level in the tropics. Originally, the various trees and plants in the rainforests play an important role of locking up atmospheric carbon in their photosynthesis. However once forests are burned, degraded and cleared, the opposite effect occurs, as large amounts of carbon dioxide as well as other harmful greenhouse gases are released into the atmosphere. With a tragic loss of biodiversity in these forests, the global carbon dioxide levels have increased from 313 ppm to 375 ppm over the past 40 years. (geography, N/A) This is mainly due to the deforestation and biodiversity loss in the world’s tropical rainforests that are supposed to take in 50 percent of the global emission. (mcspotlight, N/A) However, with so little trees and plants left in the rainforests, carbon dioxide produced from cutting down trees, but also from the action of burning trees have caused a dramatic increase in the global carbon dioxide level.
The final cause of biodiversity loss in tropical rainforests is logging. As a great number of trees are cut down every year in order to fulfill human needs. Logging tropical hardwoods such as teak, mahogany, rosewood, building materials, charcoal and other wood products to produce paper is a very lucrative business making huge amounts of profit. Several species of tropical hardwoods of over 11 million cubic meters are imported by a lot of developed countries such as the United States, just to build coffins that are then buried or burned. (rainforests, 4th November 2010) The demand for tropical hardwoods have been so massive that some countries that have been famous for exporting large amounts of wood are now importing because they have already exhausted their wood supply by destroying their native rainforests. The Philippines, Nigeria, Malaysia and Thailand will also soon run out of wood supply within the next five years. (s-cool, N/A) Although logging rainforest is a large source for finances, the immense environmental damage that has been done to the rainforests is irreversible.
The devastating biodiversity loss have affected the nutrient cycle in tropical rainforests as well. Before the loss of a great number of plants and trees, rainforests had a healthy nutrient cycle. Trees produced much oxygen and protected the forest floor from heavy precipitation, where leaves fell to the floor, litter was broken down and nutrients were given to soil, not lost through leaching. However after trees have been cut down for human benefits, there are not enough trees to protect the forest floor from precipitation. There are no leaves, no organic matter, very few nutrients go to soil, and a great deal of nutrients are lost by leaching. With less trees in the rainforests, soil is severely degraded as leaching happens more rapidly. For example, US researchers studied deforested land in Mexico and found that soil levels of phosphorus which is a key nutrient for plants decreased by 44% because the forest’s nutrient cycle was affected. (ncbi, 8th May 2010)
In conclusion, the several factors that cause the tragic loss of biodiversity in the world tropical rainforests are globalization and cattle ranching, hydroelectric power stations, migration as well as logging. Although people are trying to minimize the negative effects brought to Earth by carrying out afforestation projects and setting up policies to protect rainforests, the consequences continue to put numerous forest lives in danger. Despite the small efforts, the loss of biodiversity in tropical rainforests have led to a disrupted ecosystem and nutrient cycle, soil erosion and a rise in carbon dioxide level.
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