temperate rain forest

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Temperate rain forest


A temperate rain forest is an evergreen, broad-leaved, or coniferous forest which generally occurs in a coastal climate with cool to warm summers, mild winters, and year-round moisture abundance, often as fog. Broad-leaved temperate forests are found in areas including western Tasmania, southeastern Australia , New Zealand, Chile, southeastern China, and southern Japan. They often have close evolutionary ties to tropical and subtropical forests.

Temperate conifer rain forests are more cold-tolerant than broad-leaved rain forests and are rich in mosses while lacking tree ferns and vines. The original range of the temperate conifer rain forest included portions of Great Britain, Ireland, Norway, and the Pacific Coast of North America. The Pacific Northwest (PNW) rain forest extends from Northern California to the Gulf of Alaska and is the most extensive temperate rain forest in the world. The eastern boundary of the PNW forest is sometimes set at the crest of the most western mountain range and sometimes extended further east to include all areas in the maritime climatic zone, which has mild winters and only moderately dry summers. These forests are dominated by Douglas fir (Pseudotsuga menziesii ), western hemlock (Tsuga heterophylla ), sitka spruce (Picea sitchensis ), western red cedar (Thuja plicata ), coastal redwoods (Sequoia sempervirens ), and associated hardwoods and conifers. In the absence of harvesting, these forests are regenerated by small wind storms and very infrequent catastrophic disturbances.

The PNW forests are noteworthy in many ways. Of all the world's forests, they have the tallest trees, at 367 ft (112 m), and areas with the highest biomass (4,521 Mt per ha). On better sites the dominant species typically live 400 to 1,250 years or more and reach 313 ft (14 m) in diameter and 164328 feet (50100 m) in height, depending on site and species.

The natural temperate rain forest is generally less biodiverse than its tropical counterpart, but still contains a rich flora and fauna , including several species that are unique to its ecosystem . Preservation of temperate rain forests is a global conservation issue. Humans have virtually eliminated them from Europe and left only isolated remnants in Asia, New Zealand, and Australia. In North America, sizeable areas of natural rain forest still exist, but those not specifically reserved are predicted to be harvested within 25 to 50 years.

The same pressures that previously converted most of the natural temperate rain forests to plantations and other land uses still threaten the remaining natural forests. There is the desire to harvest the massive trees and huge timber volumes before they are lost to insects or wind blow. There is also the desire to replace slow-growing natural forests with younger forests of fast-growing species. Those who favor preservation cite the connection between intact rain forests and high salmon/trout production. They note that the replacement forests, being simpler in structure and species composition, cannot offer the same biological diversity and ecosystem functioning. Also extolled are the aesthetic, spiritual, and scientific benefits inherent in a naturally functioning ecosystem containing ancient massive trees.

See also Biodiversity; Clear-cutting; Deciduous forest; Deforestation; Forest Service; Tropical rain forest

[Edward Sucoff and Klaus Puettmann ]


RESOURCES

BOOKS

Adam, P. Australian Rainforests. Oxford: Clarendon Press, 1992.

Franklin, J. F. "Pacific Northwest Forests." In North American Terrestrial Vegetation, edited by M. G. Barbour and W. D. Billings. Cambridge: Cambridge University Press, 1988.

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temperate rain forest Forest that develops in temperate regions where rainfall is high (typically 1500–3000 mm) or fog is frequent (e.g. on the Pacific coast of North America). Broad-leaved evergreen trees are common, conifers are often present, and there are many epiphytes and climbers. Such forests occur in coastal areas of the south-eastern United States and north-western North America, in southern Chile, in parts of Australia and New Zealand, and in southern Japan and China.

views updated

temperate rain forest Forest that develops in temperate regions where rainfall is high (typically 1500–3000 mm) or fog is frequent (e.g. on the Pacific coast of N. America). Broadleaved evergreen trees are common, conifers are often present, and there are many epiphytes and climbers. Such forests occur in coastal areas of the south-eastern United States and north-western N. America, in southern Chile, in parts of Australia and New Zealand, and in southern Japan and China.