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Peter H. Raven


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orests are the planet's largest reservoir of biological diversity, containing an estimated half of all the world's plant and animal species. They also play a vital role in maintaining "ecological services" such as the water and carbon cycles, by storing carbon, conserving soils and generating rainfall.

There are probably very few truly virgin forests left on Earth. Most have been burned, replanted or otherwise influenced by humans at various times. Ecologists are replacing their model of natural forests as ancient pristine entities with models that characterize them as dynamic, unstable and short-lived [1]. Nonetheless, the scale and pace of anthropogenic "deforestation" in the past 200 years dwarfs anything seen before. The most endangered ecosystem types include tropical dry forests and mountain forest ecosystems, such as cloud forests.

Overall, human activity has removed roughly half of the world's natural forests, with the greatest losses in densely populated countries. With the exception of Russia, less than 1 percent of Europe's "old-growth" forests remain, while some 95 percent of the continental United States' forests have been logged since European settlement began [2]. Most forest remains in the least densely populated forested regions -- the major equatorial rainforests of Central Africa, the Amazon basin and the Southeast Asian islands of Sumatra, Borneo and New Guinea, as well as the boreal forests of Siberia and North America [3]. [Add]

Pressures on forests include high population growth rates, making demands on land for farming in particular; industrial enterprise based on natural resources, such as for timber and pulp production; and demand for fuelwood and charcoal, which consumed 80 percent of the timber cut in developing countries in 1995 [4]. Piecemeal forest removal has also fragmented forest regions, which has a disproportionate effect on species diversity by limiting the ecosystem's ability to recover from catastrophes such as fires and by reducing species mobility [5]. [Add]

Most of the 10 percent recorded loss of the world's natural forests between 1970 and 1995 occurred in the tropics, where population growth rates are fastest [6]. Between 1990 and 1995, the greatest amount of forests were lost in Latin America, followed by Africa and Asia. Annual deforestation rates were highest in fast-growing and already densely populated countries -- exceeding 3 percent in Bangladesh, Pakistan, the Philippines and Jamaica [7]. [Add]

Poverty and wealth distribution are also important determinants of forest survival. Many poor countries and communities rely heavily for income and exports on exploiting forest products, alongside agriculture, while richer countries and communities may have other sources of income. The fastest destruction often occurs when large numbers of people are forced to migrate into the forests, usually because of urban unemployment, rural land shortages, fast-growing populations, the creation of refugees or a combination of these. [Add]

Government policies can also be important. Most forests in tropical countries are state-owned, so migration of people into forests usually requires official sanction as well as government-built infrastructure, such as roads and organized farming programs. The deforestation of the Brazilian Amazon has spread from east to west as roads and development projects have penetrated the forest. Much of Indonesia's forest has been converted into farms as a result of the national transmigration program, which has moved some 4 million people from densely populated areas to thinly populated forested provinces such as Kalimantan and Irian Jaya.


[original and current forest area]


[protected forest area]

Failures of governance also contribute by encouraging resource plundering. In 1999, in the aftermath of the fall of President Suharto, the majority of Indonesian timber on the international market was illegally logged [8]. Globalization of trade in forest products, especially timber, encourages the removal of control over forests from native people, who have the most incentive to maintain forests for future generations. Poor forest management has left natural forests unable to regrow and often vulnerable to forest fires, such as those that spread through Indonesia in the 1990s. [Add]

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In the 1990s forests were estimated to be soaking up a third of all CO2 emissions from fossil-fuel burning, due to the "fertilization effect" of the extra CO2 in the air. But this will not last. United Nations scientists warned in the third assessment of the Intergovernmental Panel on Climate Change (IPCC) that warming will soon neutralize this effect by speeding up the decay of plant matter in forests. Warming may also trigger droughts and forest fires that could drastically reduce the forest cover in the tropics. [Add]

Natural forests -- once characterized as "jungle" that required "clearing" -- are now increasingly regarded as important ecological and economic resources for both nations and the planet. They stabilize the landscape by generating rainfall and maintaining soil, groundwater and river flows. They are also a major cultural resource as the homelands and direct sources of natural wealth for indigenous peoples, such as the reindeer herders of Siberia and the tribes of the Amazon, Borneo and New Guinea. The economic value of a sustainable harvest of fruits, nuts, rubber, rattan, medicinal plants and meat frequently exceeds the one-off value of clear-felling. [Add]

Most countries eventually adopt conservation measures to protect surviving natural forests -- often following a natural disaster attributed to deforestation. In 1998, after floods did extensive damage on the River Yangtze, China banned further logging in some watersheds and launched a replanting program. Chinese scientists also partly blame deforestation for the falling water flows in the Yellow River.

In the past two decades, the temperate northern latitudes have seen a modest increase in forest cover. However, this was mainly of commercial forest stands, which have much lower species diversity and ecological value than natural "old-growth" forests. And many European forests are in poor health, primarily because of air pollution.

Moreover, the felling of old-growth forests continues, often with state subsidies -- for instance in the northwest of the United States and the temperate rainforests of the Canadian west coast. Western and Japanese timber companies have frequently "exported" their destruction of natural forests to tropical regions: Southeast Asian forests are a major source of hardwood timber for Japan. [Add]

The 1990s saw the first worldwide efforts to halt the decline of tropical forests. Studies for the International Tropical Timber Organization (ITTO) at the start of the decade found that less than 1 percent of logging was carried out sustainably (with recovery to a similar ecological value) [9]. Consumer boycotts of tropical timber grew in protest, and by the end of the decade more than 15 million hectares of forestry projects had received certificates of their sustainability from the Forest Stewardship Council, a coalition including foresters, conservation and community groups, timber traders and certification organizations. Certified timber products can command a premium price. [Add]

Economists and environmentalists have also sought to give tangible economic worth to the undoubted ecological value of natural forests as watershed protectors, storehouses of biological diversity, and recreational and spiritual assets. The 1992 Convention on Biological Diversity gave countries new rights to the ownership of the genetic resources in their forests, which could find value in pharmaceuticals or new crops, although this has yet to prove profitable. Ecotourism, a fast-growing industry, is being actively encouraged.

The potential commercial value of fast-growing trees planted to soak up carbon dioxide (CO2) from the atmosphere and act as carbon "sinks" has also been recognized -- and backed by the 1997 Kyoto Protocol on Climate Change. Carbon credits earned by planting these forests will be tradeable with countries wanting to offset them against emissions, which are limited under the Protocol. However, management of sink forests to maximize their carbon absorption often reduces their ecological value. [Add]

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