Tropical rainforests – causes and effects of deforestation, and possible alternatives to current practices
Tropical rainforests are the most alive places on earth. Covering less than 12% of the land’s surface, the rainforests are home to more than half of all living species (Lewis, 4). 90% of all non-primates reside in tropical rainforests. Two-thirds of known plants, 40% birds of prey, and 80% of all insects are found only in tropical rainforests. Of the 2.5 to 5 million animals species thought to exist, only about one-half have been identified to date. The vast majority of rainforests are found in Brazil (Amazon), South Asia, Africa, and Central America. (WRM, 16).
The two main types of rainforest are equatorial rainforests and tropical rainforests. Equatorial rainforests make up about two-thirds of all rainforests, and is found bordering the equator in Brazil, Zaire, and Southeast Asia. The temperature and the rainfall in equatorial rainforests are the same year-round. Tropical rainforests, on the other hand, are found north and south of the equatorial rainforests, and they have definite wet and dry seasons. (http://www.waste.org/…).
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Rainforests are named so because of the rain they create within themselves. From morning to noon, as the sun heats the forests, the trees transpire hundreds of liters of water. This water forms large cumulonimbus clouds which start raining by 2 or 3 o’clock in the afternoon. Most of the rainfall stays on leaves of the tallest trees, in the canopy. The next day, this water evaporates to fall again as rain. (http://www.waste.org/…).
Tropical rainforest vegetation grows in layers. The topmost layer of the rainforests consist of emergent trees which tower up to 160 feet above the forest floor. The canopy, the next layer, is the most luxuriant layer in the rainforest. Most rainforest life grows and dwells in this layer. It is a tangled mass of vines, treetops, and other plants, and rises about 100-130 feet above the floor. The understorey rises about 50-80 feet, and it is made up of shrubs, bushes, seedlings, and saplings. Because of a lack of light, the forest floor is typically bare. Only some scattering of leaves, decaying plant matter, and other small plants can be found on the rainforest floor. (Lewis, 16).
Each layer of the rainforest is a unique habitat, and animals from one layer rarely venture into another one. Mammals such as elephants, deer, and tiger dwell on the forest floor. Primates such as gibbons, howler monkeys, and chimpanzees dwell in trees. Other tree-dwellers include sloth, squirrels, mice. One out of three bird species in the world nest in rainforests – about 2,600 species in all. These exotic birds, such as toucans, hornbills, and fly-catchers, form a massive array of color against the green background. (Lewis, 20-21).
Relationships between organisms in the rainforest is a complex web of intimate connections and interdependencies. For example, insects pollinate a large variety of plants, which in turn are food for other insects and herbivores. Insects and herbivores are food for birds and carnivores. These predators keep populations in check as well as recycle nutrients to plants through their waste. (Wills, 39).
Rainforests are ideal sources of food, medicine, and other valuable resources. They are also homeland and a spiritual basis for millions of people worldwide. An estimated 50 million tribal people live within the world’s tropical forests. They rely completely on the forests for their livelihood, using the forests for food, shelter, agricultural implements, herbs for their traditional medicines, and fiber and dyes for their clothes. (WRM, 18).
Rainforests play a significant role in regulating global climate. Various activities of the rainforest affect the amount of solar energy that reaches the earth’s surface and the amount of energy that is retained as heat. They cool the earth’s surface by pumping enormous amounts of water into the atmosphere which generate clouds that reflect back sunlight. The tropical rainforests also spread out solar radiation to temperate zones through the water vapors which carry latent heat energy and condense as rain. (WRM, 14).
Local and regional precipitation and temperature is also influenced by the forests’ large expanse of vegetation cycling water. Rainforests are fundamental to rainfall patterns. For example, research in the Amazon has shown that at least 50% of rain falling over the Amazon basin is returned to the atmosphere through evapotranspiration. (WRM, 15).
Rainforests also stabilize soils and hold back erosion through their intricate and elaborate root systems. These root systems also store much of the annual rainfall, which is slowly released over the year to recharge ground waters and keep streams and rivers flowing during the dry season. Rainforests are well adapted to surviving on nutrient-poor soils, which enable them to develop ecosystems that are highly productive and sustainable. (WRM, 19-20).
Tropical forests also provide a natural defense against hurricanes, cyclones, and typhoons. When storms move over land, the forests absorb much of the punch of winds and prevent storm-lashed tides from eroding beaches and shorelines in coastal areas. Rainforests also help to prevent droughts and floods. (Lewis, 32).
Worldwide, all tropical countries have experienced a massive increase in the rate of deforestation this century, especially after the Second World War. The causes of deforestation are many. These include commercial logging, cattle ranching, building of hydroelectric dams, mining, industry, and colonization of forests by peoples. Building of highways, pollution, and tourism also contribute to the accelerated rate of rainforest destruction.
Commercial logging accounts for about 15% of deforestation every year. The tropical timber industry is responsible for degrading about 5 million hectares of primary rainforests annually. Logging is the main cause of rainforest deforestation in both Southeast Asia and Africa. (http://www.waste.org/…).
The damage caused by commercial logging has devastating effects. Current logging practices in Malaysia, for example, leave about 33 trees damaged for every 26 trees logged as timber. In some areas, up to 70% of remaining trees die from injuries. (WRM, 51). In other parts of the world, the standard practice of logging is to roam the forest cutting any likely-looking trees. As these trees crash down, they pull other entangled plants and vines. A huge gap in the forest floor is left behind, filled with debris and tree trunks. Bulldozers then come and create more permanent damage as they haul out felled trees. (Holmes, 40). Much of the logged forests are never replanted, even with government mandates, which largely remain unenforced. Countries which were once rich in timber forests, such as the Philippines or Thailand, now need to import timber for their own domestic needs. (Scott, 35).
Logging impacts biological diversity the most. Each species requires a narrow set of ecological conditions. Once forests are reduced to tracts of isolated pockets, the fragments begin to lose species. Even if plants and animals are not directly affected by logging, if the animals they are dependent upon die, they are prone to extinction. Scientists estimate that 12% of the bird species in the Amazon and 15% of the plants in Central and South America belong the “the Living Dead” – organisms for which individuals are still found but their species population is not biologically viable. (WRM, 52).
Cattle ranching is the main cause of deforestation in Latin America, accounting for over 72% of cleared forests. (http://www.waste.org/…). The lands which have been cattle-ranched becomes depleted of its nutrients quickly as well as invaded by toxic weeds rapidly. Ecological destruction caused by cattle ranching, therefore, is often long-term and irreversible. Within a few years, the former rainforest soil becomes exhausted and it washes away. Ranchers are then forced to move to previously undisturbed tracts of forests. (WRM, 43-46).
In the Brazilian Amazon, real estate speculation is a major cause of deforestation. A centuries-old practice there is to grant the right of possession to whoever deforests a piece of land. These rights of possessions are soon full rights of ownership. The only thing people have to do to claim land is show that they are using it, and the easiest way for them to do this is by clearing it. (Fearnside, 216).
The amount of tropical rainforests which have been lost to dams is alarmingly high. As developing nations seek to ‘hydro-industrialize,’ the forest becomes increasingly threatened. So far, the reservoirs of large dams worldwide have submerged a land area the size of Italy. Eventually, dams will have flooded about 2,346 kilometers of forest. (WRM,47).
The social and ecological effects of the building of dams have been severe. In India, between 1950 and 1975, for example, 479,000 hectares of land was flooded. In Brazil, the Tucurai Dam flooded 271,000 hectares of rainforest. More dams in Central and South America continue to fill up and destroy thousands of acres of virgin forest. (WRM, 47).
Mining and industrial development continue to cause more deforestation and ecological degradation. They also aid in social impoverishment of the local inhabitants.
Clashes between indigenous people and miners are common occurrences. One example is the Grande Carajas Project in Brazil. Carajas is the site of the world’s largest deposit of high-grade iron ore. The project seeks to open up the north-east part of the country to industry and industrialized agriculture, which will affect one-sixth of the Brazilian Amazonia. The immediate threat is from the iron smelters and charcoal plants being set up along the railway. The project will likely lead to severe water and air pollution, and as a whole will affect the homelands of at least 23 tribal groups. (Terbourgh, 194). At least 700 mines exist in the Brazilian Amazonia today; many of them are illegal. The Brazilian government has plans to also industrialized parts of the Amazonia. (WRM, 62).
In much of the third world, many peasants are forced to cultivate more and more marginal lands as the best lands are taken over for cash crop productions. Many governments also seek to dispossess peasants and indigenous forest peoples for industrialization, hydroelectric dams, and other projects. Many countries have increasing numbers of the landless poor who flock to the nearest tracts of unoccupied forests to burn trees and grow food. (Holmes, 42).
An example of a recent project to colonize rainforests is Brazil’s Polonoroeste
Project, which involved the building of a central highway through the state of Rondonia, with smaller roads branching out into the jungle. In the mid-1980’s, the roads were bringing about 70,000 to 80,000 settlers into Rondonia every year. As they discovered the infertility of the soil here, they abandoned the land which was often used by entrepreneurs to graze cattle, which prevented any chance of forest recovery. (WRM, 64). The increasing number of settlers moving from Rondonia to Roraima, a state for which no deforestation data is available, suggests that deforestation in the Amazon has progressed farther than previously thought. (Fearnside, 214).
Malaysia also has a land resettlement program, in which extensive lowland forests are converted into cash crop plantations. The Federal Land Development Agency (FELDA) has primarily been in charge of overseeing the project, with oil and rubber being the main crops. Indonesia’s “Transmigration Programme” also intends to resettle people from densely populated cities such as Java, Lambok, or Bali into less settled areas. This project is implemented at the expense of Indonesia’s rainforests; it is estimated that at least one-third of the forest cover has been lost since 1950. This program threatens tribal peoples by alienating them from their homeland and forcing them to abandon their cultures. (WRM, 67-69).
In Southeast Asia, especially Malaysia and Indonesia, rainforests converted to agricultural use – both instigated by governments and private conversion by migrants – remains the prime cause of deforestation. (Scott, 35). Slash and burn agriculture accounts for at least 60% of rainforest destruction worldwide (http://www.waste.org/…).
Highways contribute to the deforestation of rainforests because they enable loggers and others to enter previously inaccessible areas. The extensive network of roads and trails needed to haul logged wood out of the forests is a major source of erosion also. Such erosion adds to the silt and sedimentation being deposited into rivers and lakes, which drastically reduce populations of fish and other aquatic organisms. (WRM, 70).
Pollution from use of motor cars, emission of thousands of man-made chemicals, and an enormous increase in power generation and industrialization of agriculture have all contributed to the death of many rainforest trees. Acid rains causes the death of many aquatic organisms in lakes and streams worldwide. It is also changing the chemistry of the soil. In Sweden, for example, soils have become ten times more acidic than they were 30 years ago. As a result, toxic elements such as aluminum have become soluble and available to plants, while necessary elements such as magnesium and potassium have been run off. This has caused severe weakening of many plants, and they are less able to resist atmospheric pollutants and extreme weathers. (WRM, 72).
Tourism is also a cause of rainforest deforestation. While creation of national parks and other tourist facilities are helping to protect many forests, the building of these facilities has forced the resettlement of many indigenous people. (WRM, 74). Tourism is also an added stress on the environment. In Nepal, for example, tourists who come to climb the Himalayan mountains leave behind tons of trash, and they use more resources per person than the natives.
Deforestation of the tropical rainforests impacts the whole world in a massive way. Loss of biological diversity means loss of a wide and varied gene pool which ensures a healthy, balanced ecosystem. The disturbance of global weather presents a major problem. As well as significantly reducing rainfall and increasing surface temperature in rainforests, deforestation causes a global warming through the greenhouse effect. Deforested areas cannot absorb solar energy. They also emit carbon dioxide, methane, and nitrous acid, chemicals which are regulated by the rainforests. Predicted consequences of global warming include rising sea levels, increased storm intensities, altered weather patterns, and forest die back. (Lewis, 33).
Deforestation is causing severe ecological degradation, such as erosion, desertification, floods, and droughts in many parts of the world. Once rainforests have been cut down, essential nutrients are quickly washed out of the soil. Cultivation drastically increases the rate of soil erosion. According to Carl Jordan of the University of Georgia, as much as one-half of the soil’s organic content will have been lost just three years after the land has been cleared for agriculture. (WRM, 30). Desertification arises as people clear land, deplete it, and search for more forested lands to clear. Clearing of forest also dramatically increases surface run-off from rainfall. Most often, the consequences are massive flooding. Flooding seasons alternate with the dry seasons, when rivers and streams are not replenished by the rainforests. Much of the famines striking many countries can be blamed directly or indirectly on deforestation, such as in Ethiopia, India, and other parts of Southeast Asia (34-35).
Are there any solutions to the problems of deforestation, or is there another way to deforest to lessen the impact? In theory, individual countries can choose to leave their forests untouched. However, few, if any, have the luxury to do so. The previously forested land can be transformed to provide jobs, homes, and food for many people. (Scott, 35). However, according to Margaret Scott, conservative logging can be practiced. Tropical forests theoretically can be selectively logged with only the largest trees extracted, and the forest can be left fallow for a time to allow it to regenerate so it can be logged again. “If logged properly, a production forest retains most of the diversity of its plants and wildlife. It also continues to act as a buffer against erosion and climatic change (35).”
Bob Holmes suggests other alternative ways of logging. He says loggers should first draw an inventory of the specific chosen location and the species of trees they plan to cut. Skidder (bulldozer) trails should be planned out in advance. They should cut vines from selected trees and allow them to wither to prevent unnecessary secondary damage, and they should focus on selectively killing undesired trees. According to a study done by Chris Uhl of Pennsylvania State University, these practices produced better results:
Vine cutting reduced the number of damaged trees by 30%, and careful mapping of skidder trails reduced the affected area by 25%. (Holmes, 41).
A fundamental problem of deforestation is that the groups of people who profit from deforestation are not the same people who pay for the resulting environmental, social and financial costs. The majority of the problems are left behind for future generations to deal with, while deforestation causes immediate profits and meets the basic needs of many people today.