Lester R. Brown
Chapter 3. Signs of Stress: The Biological Base: Forests Shrinking
At the beginning of the twentieth century, the earth's forested area was estimated at 5 billion hectares. Since then it has shrunk to 2.9 billion hectares—an area roughly double the world's cropland area. The remaining forests are rather evenly divided between tropical and subtropical forests in developing countries and temperate/boreal forests in industrial countries.23
Deforestation is caused by the growing demand for forest products and the growing conversion of forested land to agricultural uses. This forest loss is concentrated in developing countries. From 1990 to 1995, the loss in these nations averaged 13 million hectares a year, an area roughly the size of Kansas. Overall, this means that the developing world is losing 6.5 percent of its forests per decade. The industrial world is actually gaining up to an estimated 3.6 million hectares of forestland each year, principally from abandoned cropland that is returning to forests on its own, as in Russia, and the spread of commercial forestry plantations.24
Unfortunately, even these official FAO data do not reflect the gravity of the situation. For example, tropical forests that are clearcut or burned off rarely recover. They simply become wasteland or at best scrub forest, but they are still included in the official forestry numbers if they are not included in another land use category such as cropland or building construction. The World Resources Institute's Forest Frontiers Initiative issued a report in 1997 on the status of the world's forests. They note that "hidden behind such familiar statistics is an equally sobering reality. Of the forests that do remain standing, the vast majority are no more than small or highly disturbed pieces of the fully functioning ecosystems they once were." The report notes that only 40 percent of the world's remaining forest cover can be classified as frontier forest, which they define as "large, intact, natural forest systems relatively undisturbed and big enough to maintain all of their biodiversity, including viable populations of the wide-ranging species associated with each type."25
Use of each of the principal forest products—firewood, paper, and lumber—is expanding. Of the 3.28 billion cubic meters of wood harvested worldwide in 1999, over half was used for fuel. In developing countries, the share was far higher, nearly four fifths of the total. In industrial countries, roughly 14 percent of the wood harvested was used for fuel, much of it the waste wood used by pulp and paper mills to generate electricity and to provide process heat. Using the bark and small branches for fuel, some paper mills are energy self-sufficient.26
Deforestation to satisfy fuelwood demand is extensive in the Sahelian zone of Africa and the Indian subcontinent. As urban firewood demand surpasses the sustainable yield of nearby forests, the woods slowly retreat from the city in an ever larger circle, a process clearly visible from satellite photographs taken over time. As the circles enlarge, the transport costs of firewood increase, triggering the development of an industry in charcoal, a more concentrated form of energy with lower transportation costs.27
Logging also takes a heavy toll, as is evident in countries in Africa, the Caribbean, and the Pacific. In almost all cases, logging is done by foreign corporations more interested in maximizing the harvest of forest products on a one-time basis than in managing forests to maximize sustainable yield in perpetuity. Once a country's forests are totally clearcut, companies typically move on, leaving only devastation behind.28
Another loss of forests comes from clearing land for agriculture and plantations, usually by burning, a loss that is concentrated in the Brazilian Amazon and more recently in Borneo and Sumatra in Indonesia. After losing 97 percent of the Atlantic rainforest, Brazil is now destroying its Amazon rainforest. This huge forest, roughly the size of Europe, was largely intact until 1970. Since then, 14 percent of Brazil's rainforest has been lost. In 1999 alone, 17,000 square kilometers were deforested.29
The progressive loss of forest cover has both economic and environmental consequences. Economically, the countries that have lost their exportable supplies of forest products, such as Nigeria and the Philippines, are now net importers of forest products. Also lost are the jobs and income that their forest industries once provided.30
The environmental effects of deforestation are becoming all too visible. Scores of countries are suffering from disastrous flooding as a result of deforestation. In 1998, the Yangtze River basin, which has lost 85 percent of its original tree cover, experienced some of the worst flooding in its history. In 2000, Mozambique was partially inundated as the Limpopo overflooded its banks, taking thousands of lives and destroying homes and crops on an unprecedented scale. The Limpopo river basin, which has lost 99 percent of its original tree cover, will likely face many more such floods.31
While deforestation accelerates the flow of water back to the ocean, it also reduces the airborne movement of water to the interior. The world's forests are in effect conduits or systems for transporting water inland. Eneas Salati and Peter Vose, two Brazilian scientists writing in Science, observed that as moisture-laden air from the Atlantic moves westward across the Amazon toward the Andes, it carries moisture inland. As the air cools and this moisture is converted into rainfall, it waters the rainforest below. In a healthy rainforest, roughly one fourth of the rainfall runs off into rivers and back to the Atlantic Ocean. The other three fourths evaporates and is carried further inland, where the process is again repeated. It is this water cycling capacity of rainforests that brings water inland to the Amazon's vast western reaches.32
If the rainforest is burned off and planted to grass for cattle raising, then the cycling of rainfall is dramatically altered—three fourths of the rainfall runs off and returns to the sea the first time it falls, leaving little to be carried inland. As more and more of the Amazon is cleared for cattle ranching or farming or is degraded by loggers, the capacity of the rainforest to carry water inland diminishes. As a result, the western part of the forest begins to dry out, changing it into a dryland forest or even a savanna.33
The burning and cutting of the Amazonian rainforest could also affect agriculture in regions to the south. As the air masses moving inland from the Atlantic reach the Andes, they turn southward, carrying moisture with them. It is this moisture that provides part of the rainfall in the agricultural regions of southwestern Brazil, Paraguay, and northern Argentina. As the deforestation of the Amazon progresses, the flow of moisture to these farming areas will likely diminish. Efforts to boost farm output by clearing land in the eastern Amazon basin could reduce farm output in southwestern Brazil.34
A similar situation may be developing in Africa, where deforestation and land clearing are proceeding rapidly as the demand on firewood mounts and as logging firms clear large tracts of virgin forests. As the forest area shrinks, the amount of rainfall reaching the interior of Africa is diminishing. A comparable trend is unfolding in China. Wang Hongchang, a Fellow of the Chinese Academy of Social Sciences, cites deforestation in the southern and eastern provinces of China as a key reason for the rainfall decline in the country's northwest, the area where the dust bowl is forming.35
A number of countries now have total or partial bans on logging in primary forests, including Cambodia, China, India, New Zealand, the Philippines, Sri Lanka, Thailand, and Viet Nam. Additionally, about 3 million square kilometers, accounting for roughly 9 percent of the earth's remaining forest area, are set aside as parks or nature preserves or for other conservation reasons. In some cases, the forests that are set aside are carefully protected, but all too often these "paper parks" exist only in theory and in the meaningless laws that set them up.36
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