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Rainforest

Exploitation Of Rainforests

Natural rainforests are an extremely valuable natural resource, mostly because they typically contain very large individual trees of commercially desirable species. These trees can be harvested and manufactured into lumber, plywood, paper, and other valuable wood products. Tropical rainforests, for example, contain large trees of commercially important species of tropical hardwoods, such as African mahogany (Khaya and Entandrophragma spp.), American mahogany (Swietenia spp.), Asian mahogany (Shorea spp. and Parashorea spp.), balsa (Ochroma spp.), ebony (Diospyros spp.), rosewood (Dalbergia spp.), rubber (Hevea brasiliensis), and yang (Dipterocarpus spp.). Temperate rainforests are also extremely valuable, because their large trees can be harvested and converted into economic products.

However, because they have little or no net production of tree biomass, it is a common practice in industrial forestry to clear-cut old-growth rainforests and then convert them into more productive, secondary forests. Even though another forest regenerates on the harvested site, sometimes dominated by the same tree species that occurred initially, this practice should be viewed as an ecological conversion that results in a net loss of old-growth rainforest as a natural ecosystem. All ecological conversions have attendant risks for species that require the particular habitats of the original ecosystem.

In other cases, trees may be selectively harvested from old-growth rainforests so that the physical and ecological integrity of the forest is left more or less intact. This is especially true of temperate rainforests, which unlike tropical rainforests, do not have interlocking webs of lianas in their overstory, so that the felling of one large tree can bring down or badly damage other trees in its vicinity. However, even selective harvesting changes the character of old-growth rainforests, so that they are no longer in their natural condition. As such, the selectively harvested ecosystem would no longer provide habitat for many of the species that depend on the habitats available in the original, old-growth rainforest. Nevertheless, selective harvesting results in a much less intensive ecological conversion than that associated with clear-cutting.

Because old-growth rainforests are natural ecosystems, they are considered to have great intrinsic value, which is degraded when they are harvested or otherwise disturbed. The intrinsic value of rainforests is further enhanced by the enormous richness of species of plants, animals, and microorganisms that are dependent on this specific ecosystem, particularly in the tropics. Mostly because of the intrinsic biodiversity-related value of rainforests, it is critically important that not all of the world's tracts of these natural ecosystems are converted to human uses. To prevent this terrible damage from occurring, extensive landscapes of the world's remaining rainforests, in both tropical and temperate regions, must be protected in ecological reserves and parks, where no more than traditional uses by humans are permitted.

Resources

Books

Begon, M., J.L. Harper, and C.R. Townsend. Ecology. Individuals, Populations and Communities. 2nd ed. London: Blackwell Sci. Pub., 1990.

Davis, W. Rain Forest: Ancient Realm of the Pacific Northwest. Chelsea Green Publishing Co., 1999.

Freedman, B. Environmental Ecology. 2nd ed. San Diego: Academic Press, 1995.

Hancock P.L., and B.J. Skinner, eds. The Oxford Companion to the Earth. Oxford: Oxford University Press, 2000.

Maloney, B.K. (ed.). Human Activities and the Tropical Rain-forest: Past, Present, and Possible Future. Kluwer Academic Publishers, 1998.

Taylor, Leslie. Herbal Secrets of the Rainforest: Over 50 Powerful Herbs and Their Medicinal Uses. Rocklin, CA: Prima Publishing, 1998.


Organizations

Rainforest Alliance [cited March 2003]. <http://www.rainforestalliance.org>.


Bill Freedman

KEY TERMS

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Biome

—A geographically extensive ecosystem, usually characterized by its dominant life forms.

Climax community

—The more or less stable, plant and animal community that culminates succession under a given set of conditions of climate, site, and biota.

Community

—In ecology, a community is an assemblage of populations of different species that occur together in the same place and at the same time.

Competition

—An interaction between organisms of the same or different species associated with their need for a shared resource that is present in a supply that is smaller than the potential, biological demand.

Old growth

—A late-successional forest, characterized by great age, an unevenly-aged population structure, domination by long-lived species, and with a complex physical structure, including multiple layers in the canopy, large trees, and many large-dimension snags and dead logs.

Selective cutting

—A method of forest harvesting in which only trees of a desired species and size class are removed. This method leaves many trees standing, and relies on natural regeneration to replace the harvested trees.

Species richness

—The number of species occurring in a community, a landscape, or some other defined area.

Additional topics

Science EncyclopediaScience & Philosophy: Quantum electronics to ReasoningRainforest - Tropical Rainforests, Temperate Rainforests, Exploitation Of Rainforests