Shrinking Forests, Growing Dangers: The Consequences of Deforestation

Image Gallery When forests disappear, they take animal populations, crop yields and flood protection with them. MIKE138/FLICKR

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In early December 2004, Philippine President Gloria Macapagal Arroyo “ordered the military and police to crack down on illegal logging, after flash floods and landslides, triggered by rampant deforestation, killed nearly 340 people,” according to news reports. Fifteen years earlier, in 1989, the government of Thailand announced a nationwide ban on tree cutting following severe flooding and the heavy loss of life in landslides. And in August 1998, following several weeks of record flooding in the Yangtze River basin and a staggering $30 billion worth of damage, the Chinese government banned all tree cutting in the upper reaches of the basin.

Each of these governments had belatedly learned a costly lesson, namely that services provided by forests, such as flood control, may be far more valuable to society than the lumber in those forests.

At the beginning of the 20th century, the Earth’s forested area was estimated at 5 billion hectares. Since then, it has shrunk to just under 4 billion hectares, with the remaining forests rather evenly divided between tropical and subtropical forests in developing countries and temperate/boreal forests in industrial countries. Since 1990, the developing world has lost some 13 million hectares of forest a year. This loss of about 3 percent each decade is an area roughly the size of Greece. Meanwhile, the industrial world is actually gaining an estimated 5.6 million hectares of forestland each year, principally from abandoned cropland returning to forests on its own and from the spread of commercial forestry plantations. Thus, net forest loss worldwide exceeds 7 million hectares per year.

Unfortunately, even these official data from the United Nations Food and Agriculture Organization 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, yet they still may be counted as “forest” in official forestry numbers. Plantations, too, count as forest area, yet they also are a far cry from the old-growth forest they sometimes replace.

The World Resources Institute (WRI) reports that, of the forests that still stand, “the vast majority are no more than small or highly disturbed pieces of the fully functioning ecosystems they once were.” Only 40 percent of the world’s remaining forests can be classified as frontier forest, which WRI defines 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.”

Pressures on forests continue to mount. Use of firewood, paper and lumber is expanding. Of the 3.5 billion cubic meters of wood harvested worldwide in 2005, just over half was used for fuel. In developing countries, fuelwood accounts for nearly three fourths of the total.

Deforestation to supply fuelwood 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 photos taken over time. As the circles enlarge, the transport costs of firewood increase, triggering the development of an industry for charcoal, which is a more concentrated form of energy. March Turnbull writes in Africa Geographic Online: “Every large Sahelian town is surrounded by a sterile moonscape. Dakar and Khartoum now reach out further than 500 kilometers for charcoal, sometimes into neighboring countries.”

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