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Forest Ecosystems Profile

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Forests, wooded areas, and scattered trees have provided food, fuel, medicines, filtered water, shelter, and building materials throughout time. As countries with ample forests develop, they tend to emphasize timber production over other forest services; we've already seen this process occur in Canada and the US. Now, forests' timber production is similarly helping fuel economic development in many developing countries, where more than half of the world's remaining forests are located.
Woman carries wood
Woman carries wood from rejuvenated Dhani Forest.
But in these countries, millions of people still depend on forests for food (mushrooms, fruit, nuts, other edible plants, and game), building and household materials (timber, vines, bamboo, leaves, etc.), and fodder to feed their livestock — basic everyday needs. Plus, traditional goods (woodfuels, food, and medicines) still serve as the basis for livelihoods in many rural populations. The environmental challenge for these countries is balancing national development with local needs and, at the same time, sustaining their forests.

How much of the world's forests remain?

Forests are defined as land areas "dominated by trees where the tree canopy covers at least 10% of the ground area." By this definition, forests cover about 25% of Earth's land surface, excluding Antarctica and Greenland. Before people began clearing forests for agriculture, forests covered about 20% more land than they do now. Some estimates are as high as 50% more. Since 1980, forest area has decreased by about 10% in developing countries. In tropical regions, deforestation is currently estimated to exceed 130,000 square kilometers per year. In northern hemisphere countries, forest area is holding steady or increasing. In the United States and countries in Western Europe, where nearly all forests are managed to some degree, forest area increased as previously deforested areas were replanted for production or simply allowed to regenerate.

Forest Area
Forest Area from 1980 to 1995
(click on image to enlarge)
About 40% of forests are relatively undisturbed and large enough to maintain biodiversity. These are called "frontier" forests. Nearly half are likely to be developed soon. They're concentrated in three areas: two boreal forests, one in Canada/Alaska and one in Russia, and one area of tropical forest mostly in Brazil but spanning parts of Peru, Venezuela, and Colombia.

What are the primary goods and services forests provide?

Goods

Services

Timber — In the early 1990s industrial wood products contributed about $400 billion to the global economy.

Water filtration - U.S. national forests provide water to 60 million people in 3,400 communities, a service valued at $3.7 billion per year.

Woodfuels — Woodfuels account for about 15% of primary energy supply in developing countries, up to 80% in some Sub-Saharan and Asian countries.

Carbon storage - Forests store 613-938 gigatons of carbon, making them an important natural defense against climate change.

Nontimber products — Food and fodder are the most important nontimber products to people who depend on forests as a primary source of nutrition.

Biodiversity — More than 60% of known terrestrial plant and animal species, including thousands of tree species, live in forests.



We lose much more than trees when forests disappear.

In many parts of the world — for example, New York City — forest vegetation and soils are the primary or only filter for much of the water that people in the region use. But of the 145 watersheds around the world, 42 have lost more than 75% of their original forest cover. Fifteen have lost more than 95%. In Canada, Russia, Central and Eastern Europe, and most developing countries, annual timber harvests exceed what is regrown in available forest areas. The United States and Western Europe, two of the major producers of industrial timber, currently harvest less wood from available forest land than regrows annually, but in recent years the rate of regrowth has decreased. Growing trees take up more carbon than mature trees, but they store less until they reach full size, and loss of forest and decreased growth rate mean less carbon is stored. And more carbon in the atmosphere advances global warming. Clearly, trees are one of our most effective bulwarks against global warming.

But it is the biological richness and beauty of forest ecosystems that holds tremendous appeal to many environmentalists and the general public, as witnessed by worldwide appeals to "save the rainforest," even by people who don't live near and have no direct connection to rainforests.

What is the prognosis for the world's forests?

For frontier forests the principal threats are logging, mining, fragmentation by roads and other forms of infrastructure, and clearance for agriculture. Mining is stimulated by the lucrative industrial minerals located in developing countries' forests. Logging and mining operations, eager to move products to market, are often the initial road builders. Fragmentation by roads is important because they open remote forest regions to more logging and mining and to human settlement. Roads also increase hunting and poaching, sometimes of endangered species.

Clearance for agriculture is the primary cause of forest loss in Africa. Rural subsistence farming expands as populations grow. In Latin America, large-scale cattle ranching, government development programs, and hydroelectric projects are the main causes of forest loss. In Asia, loss results almost equally from expansion of farming and development projects. In the northern hemisphere, acid rain and other pollutants have taken their toll largely on boreal forests. The greatest threats, though, continue to be fragmentation and conversion.

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Source: This profile is adapted from the companion book, World Resources 2000-2001.

For comprehensive data about the world's ecosystems, visit EarthTrends at http://www.earthtrends.wri.org/.

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