Causes and effects
There are many causes for deforestation. The first and most important cause is wood extraction. Wood has always been a primary forest product for human populations and industrial interests. Since wood is an important structural component of any forest, its removal has immediate implications on forest health. Intensive harvests can lead to severe degradation, even beyond a forests capacity to recover. When the soil has been stripped of its nutrients, farmers move further into the forests in search of new land. And perhaps the worst culprit of deforestation in the Brazilian Amazon is cattle ranching. 38% of deforestation in the Amazon was due to large-scale cattle ranching. Mining for valuable resources also plays a major role.
Deforestation has many devastating effects. It affects climate significantly, in part because the forest plays a major role in the water cycle, recycling rain back into the clouds as it receives rainfall. As a result, when the land is cleared, flooding and drought become serious problems, as rainwater travels quickly through the ground without the forest to regulate it.
The burning and felling of the forests is also exacerbating the Greenhouse Effect: approximately 10% of the heat-trapping carbon dioxide released into the atmosphere in 1987 was a result of the fires in the Amazon. It threatens the existence of indigenous peoples. There have been more extinction of tribal peoples in this century than any other, with Brazil losing 87 tribes between 1900 and 1950.
Deforestation robs the world of countless species, destroying crucial biodiversity and losing species with potential uses in medicine, agriculture and industry. Biodiversity is important because it contributes to resiliency. A world without biodiversity would be fragile and likely to amplify disturbance into catastrophe through the collapse of ecosystems that had lost keystone species. Thus, biodiversity reduction, combined with climate change, has the potential to spin out of control and to threaten the prosperity of global civilization. Already the scale of biodiversity caused by the present generation of human activities ranks with the great prehistoric extinctions. Recovery from this level of disturbance will require tens of millions of years.
At the close of the twentieth century, the world finds itself undergoing the most rapid and complete deforestation it has ever experienced under the human hand. Since 1950, a fifth of the world's forest cover has been removed. At least 55% of the world's 30 to 40 million hectares of the rare but incredibly productive rainforest have been cleared. Current rates of loss for rainforests and other ecosystems are over 20 million hectares a year, 40 hectares a minute. According to reports by the World Resource Institute and Rainforest Alliance, tropical forests account for 80% of that loss. An area almost the size of Washington State is destroyed each year, and at current rates, tropical forests will be reduced by almost half from existing levels in the next 45 years. The long-term effects of deforestation are far too great to continue devastating the forests.
Solutions
Today, both biodiversity loss and global warming have become such clear dangers to our biosphere that international treaties have addressed them both. These include the 1992 Convention on Biological Diversity, and the Framework Convention on Climate Change. Additionally, Chapter 26 of Agenda 21 of the UNCED (the 1992 Rio Conference) has addressed the loss of cultural diversity associated with global deforestation. These treaties are the most visible manifestation of a growing recognition and acceptance of the mounting costs of deforestation - costs so high that they threaten the future of human civilization.
Nevertheless, form a timber extractor's point of view, it would be foolish to pass up the opportunity to get something for nothing that is represented by primary forest logging. The returns are enormous, often 50%, and the risk is small. However, consumer awareness and concern is growing, and this is beginning to be reflected in wood product trade statistics. Austria's 1992 Tropical Timber Labeling Act was one of the first side attempts to place limits on rainforest destruction associated with logging. The 1990s have seen several other initiatives begin. Furthermore, wood product conservation and recycling is growing rapidly around the world, and alternative fiber sources are poised to emerge.
Throughout the tropics, rain forests are being cut down. By different methods and for different reasons, people in tropical regions of the world are cutting down, burning, or otherwise damaging the forests. The process in which a forest is cut down, burned or damaged is called "deforestation."
Deforestation causes the extinction of many species and changes in our global climate. If the world continues at the current rate of deforestation, the world's rain forests will be gone within 100 years--causing unknown effects to the global climate and the elimination of the majority of plant and animal species on the planet.
How Deforestation Happens
Deforestation occurs in many ways. The majority of rain forest cut down is cleared for agricultural use such as the grazing of cattle, and the planting of crops. Poor farmers chop down a small area (typically a few acres) and burn the tree trunks, a process called "slash and burn" agriculture. Intensive, or modern, agriculture occurs on a much larger scale, sometimes deforesting several square miles at a time. Large cattle pastures often replace rain forest to raise beef for the world market.
Commercial logging, the cutting of trees for sale as timber or pulp is another common form of deforestation. Logging can occur selectively, where only the economically valuable species are cut, or by clear-cutting, where all trees are cut. Commercial logging uses heavy machinery, such as bulldozers, road graders, and log skidders, to remove cut trees and build roads. The heavy machinery is as damaging to a forest as the chainsaws are to the trees.
There are other ways in which deforestation happens, such as the building of towns and flooding caused by construction of dams. These causes represent only a very small fraction of total deforestation.
Why Deforestation Happens
Because of their basic human need for food, peasant farmers often cause deforestation to raise crops for self-subsistence. Most tropical countries are very poor by U.S. standards, and farming is a basic way of life for a large part of their population. In Brazil, for example, the average annual earnings of a single person in is US $5400, compared to $26,980 per person in the United States (World Bank, 1998). In Bolivia, which holds part of the Amazon rain forest, the average earnings per person is $800. Farmers in these countries do not have the money to buy necessities and must raise crops for food and for sale.
Deforestation and the Global Carbon Cycle
Carbon dioxide (CO2) is the major gas involved in the greenhouse effect, which causes global warming. All the things that produce CO2 (like a car burning gas) and the things that consume CO2 (growing plants) are involved in the "global carbon cycle."
Deforestation increases the amount of CO2 and other trace gases in the atmosphere. When a forest is cut and replaced by cropland and pastures, the carbon that was stored in the tree trunks (wood is about 50% carbon) joins with oxygen and is released into the atmosphere as CO2.
The loss of forests has a great effect on the global carbon cycle. From 1850 to 1990, deforestation world-wide (including that in the United States) released 122 billion metric tons of carbon into the atmosphere, with the current rate being between 1.6 billion metric tons per year (Skole et al. 1998). In comparison, all of the fossil fuels (coal, oil, and gas) burned during a year release about 6 billion tons per year.
Releasing CO2 into the atmosphere increases the greenhouse effect, and may raise global temperatures (see Climate Change fact sheet). The role of fossil fuel burned by cars and by industry is well known, but tropical deforestation releases about 25% of the amount released by fossil fuel burning.
Deforestation and Biodiversity
World-wide, there are between 5 to 80 million species of plants and animals, which make up the "Biodiversity" of planet Earth (Lawton and May 1995). Most scientists believe the number of species to be between 10 and 30 million. Tropical rain forests--covering only 7% of the total dry surface of the Earth--hold over half of all of these species (Lovejoy 1997). Of the tens of millions of species believed to be on Earth, scientists have only given names to about 1.5 million of them (Stork 1997). Even fewer of these species have been studied in depth.
Many of these plants and animals of the rain forest can only be found in small areas of them, because they require a special habitat to live. This makes them very vulnerable to deforestation. If their habitat is cut down, they may become extinct. Every day species are disappearing from the tropical rain forests as they are cut. We do not know the exact rate of extinction, but estimates range from one to 137 species disappearing world-wide per day (Stork 1996, Rainforest Action Network 1998).
The loss of species will have a great impact on the planet. For humans, we are losing organisms that might have shown us how to, for example, prevent cancer or cure AIDS. Other organisms are losing species that they depend upon, and thus face extinction themselves.
After Deforestation
When the fertility of the ground becomes low, farmers seek other areas to clear and plant, abandoning the poor soil. The area previously farmed is left to grow back to a rain forest. However, just as the crops did not grow well because of the soil's poor nutrients, the forest will grow back slowly, also because of the soil's poor nutrients. After the land is abandoned, the forest typically can take 50 years to grow back.
Another type of farming practised in rain forests is called "shade agriculture." In this type of farming, many of the original rain forest trees are left to provide shade for shade-loving crops like coffee or chocolate. When the farm is abandoned, the forest grows back very quickly, because much of it was left unharmed in the first place. After this type of farming, forests can grow back as quickly as 20 years.
Other types of farming can be much worse for forest re-growth. Intensive agricultural systems use lots of chemicals like pesticides and fertilisers. The pesticides kill a lot of the living organisms in the area, and pesticides and fertilisers wash into the surrounding areas. In banana plantations, pesticides are used on the plants and in the soil to kill pest animals. However, these pesticides also kill other animals as well, and weaken the health of the ecosystem. Banana plantations also use irrigation ditches and underground pipes for transporting water, changing the water balance of the land. After a banana plantation, or other intensive agricultural system, is abandoned, it can take a great deal of time for a forest to re-grow-- possibly even centuries.
This essay should have given the reader a good overview of the topic and possible problems.
