Temperate rainforest
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Temperate rainforests are coniferous or broadleaf forests that occur in the temperate zone and receive high rainfall. Most of these occur in Oceanic-Moist Climates in Western North America (Southeastern Alaska to Central California), Western Europe (Southern Norway to Northern Spain), Southwestern South America (Southern Chile), Southeastern Australia (Tasmania/Victoria), and Western New Zealand (South Island's west coast). Others occur in Subtropical-Moist Climates (The Colchian temperate rain forests of the Eastern Black Sea region of Turkey and Georgia, New Zealand's North Island, South Africa's Garden Route, Western Japan, and the mountain temperate coniferous rain forests of Taiwan's Central Mountain Ranges). Some areas, however, such as the Russian Far East (Ussuri, Manchuria, Sakhalin) in Asia, the Rocky Mountains of British Columbia, northern Idaho and nortwestern Montana, and Rocky Mountain Trench of BC's and Montana's interior have more of continental climate but get enough precipitation in both rain and snow to harbor significant pockets of temperate rain forest. Examples include the Cariboo Mountains, Columbia Mountains, Cabinet Range, Yaak Wilderness and parts of Glacier National Park. The mountainous coniferous forests of the Changbai Mountains bordering China and North Korea are a good example contain some of the richest high-elevation coniferous evergreen forests in Eastern Asia.
[edit] Characteristics
Temperate rain forests are distinguished from other temperate forests by a few factors:
- Rainfall: high rainfall (minimum 2-3 m/year, depending on latitude), usually from moisture-laden winds off the ocean.
- Relative proximity to the ocean: temperate rain forests depend on the proximity to the ocean to moderate seasonal variations in temperature, creating milder winters and cooler summers than continental-climate areas. Many temperate rain forests have summer fogs that keep the forests cool and moist in the hottest months.
- Coastal mountains: temperate rain forests occur where mountain ranges are close to the coast; coastal mountains increase rainfall on the ocean-facing slopes.
Temperate rain forests may be predominantly coniferous (with deciduous trees in understory), broadleaf evergreen, or mixed forests with deciduous species, and occur in Temperate broadleaf and mixed forests and Temperate coniferous forests ecoregions.
The temperate coniferous rain forests sustain the highest levels of biomass in any terrestrial ecosystem and are notable for trees of massive proportions, including Coast Redwood (Sequoia sempervirens), Coast Douglas-fir (Pseudotsuga menziesii), Sitka Spruce (Picea sitchensis), Alerce (Fitzroya cupressoides) and Kauri (Agathis australis). These forests are quite rare, occurring in small areas of Western North America, southwestern South America and northern New Zealand.
[edit] Global distribution
Temperate forests cover a large part of the globe, but temperate rain forests only occur in seven regions around the world; the Pacific temperate rain forests of North America, the Valdivian and Magellanic temperate rain forests of southwestern South America, the Colchian rain forests of the eastern Black Sea region (Turkey and Georgia), the New Zealand temperate rain forests, Tasmanian temperate rain forests, South Africa's Knysna-Amatole coastal forests, and pockets of rain forest in northwest Europe and southwest Japan's Taiheiyo evergreen forests. Also, there are forests similar to those in Japan in Taiwan's Montane forests of the Central Mountain Ranges along Eastern Taiwan's Pacific Coast. Scattered small pockets of temperate rain forest also exist along the Appalachian Mountains from northern Georgia to New England, British Columbia's Columbia Mountains, and in parts of Sakhalin Island, Manchuria and the Ussuri Region of the Russian Far East in Asia.
[edit] Temperate rain forest regions
[edit] Pacific temperate rain forests of Northern/Northwestern America
A portion of the temperate rain forest region of North America, the largest area of temperate zone rain forests on the planet, are the Pacific temperate rain forests which occur on west-facing coastal mountains along the Pacific coast of North America, from Kodiak Island in Alaska to northern California, and are part of the Nearctic ecozone.
These rain forests occur in a number of ecoregions, which vary in their species composition, but are all predominantly conifers, sometimes with an understory of broadleaved trees and shrubs primarily on the coastal mountain ranges from Southeastern Alaska to Central California. British Columbia's Rocky Mountains, Cariboo Mountains, Rocky Mountain Trench (east of Prince George) and the Columbia Mountains of Southeastern British Columbia (west of the Canadian Rocky Mountains that extend into parts of Idaho and Northwestern Montana in the United States), which encompass the Selkirk Mountains, Monashee Mountains, and the Purcell Mountains, have the largest stretch of interior temperate coniferous rain forests[1] similar to those on the Pacific Coast. The difference is perhaps these inland rainforests have more of a continental climate with a large proportion of the precipitation falling as snow. Being closer to the Rocky Mountains, there is more of a diverse mammalian fauna.
A common feature of Pacific temperate rain forests of North America is the Nurse log, a fallen tree which as it decays, provides ecological facilitation to seedlings. Pacific temperate rain forests can be found in the Northern Pacific coastal forests, Queen Charlotte Islands, Vancouver Island, British Columbia mainland coastal forests, Central Pacific coastal forests, Central and Southern Cascades forests, Klamath-Siskiyou forests, and Northern California coastal forests ecoregions. The Northern California coastal forests are home to the Coast Redwood (Sequoia sempervirens), the world's tallest tree. Some of the best forests are found in Olympic National Park, Mount Rainier National Park, Tongass National Forest, Mount St. Helens National Monument, Redwood National Park, and throughout British Columbia (including British Columbia's Coastal Mountain Ranges and both Mount Revelstoke National Park and Glacier National Park (Canada) in the Columbia Mountains) with the coastal Great Bear Rainforest being the largest temperate rainforest found in the world.
[edit] Valdivian and Magellanic temperate rainforests
The temperate rain forests of South America are located on the Pacific coast of southern Chile, on the west-facing slopes of the southern Chilean coast range, and the Andes Mountains in both Chile and Argentina down to the southern tip of South America, and are part of the Neotropic ecozone. The Valdivian rainforests are dominated by a variety of broadleaf evergreen trees, like Aextoxicon punctatum, Eucryphia cordifolia, and southern beech (Nothofagus), but include many conifers as well. The Valdivian rainforests occur in the Valdivian temperate rain forests and Magellanic subpolar forests ecoregions.
The Valdivian and Magellanic temperate rainforest's are the only temperate rain forests in South America and one of a small number of temperate rain forests in the world. Together they are the second largest in the world, after the Pacific temperate rain forests of North America (which stretches from Alaska to northern California). The Valdivian forests are a refuge for the Antarctic flora, and share many plant families with the temperate rainforest's of New Zealand, Tasmania, and Australia. Fully half the species of woody plants are endemic to this ecoregion.
In the Valdivian region the Andean Cordillera intercepts moist westerly winds along the Pacific coast during winter and summer months; these winds cool as they ascend the mountains, creating heavy rainfall on the mountains' west-facing slopes. The northward-flowing oceanic Humboldt Current creates humid and foggy conditions near the coast. The tree line is at about 2,400 m in the northern part of the ecoregion (35° S), and descends to 1,000 m in the south of the Valdivian region. In the summer the temperature can climb to 62 degrees Fahrenheit (16.5 °C), while during winter the temperature can drop below 45 °F (7 °C).[2]
[edit] South Africa's Knysna-Amatole coastal rain forests
The temperate rain forests of South Africa are part of the Knysna-Amatole forests that are located along South Africa's Garden Route between Cape Town and Durban on the south-facing slopes of South Africa's Drakensberg Mountains facing the Indian Ocean. There are several coniferous podocarps that grow here. This forest receives a lot of moisture as fog from the Indian Ocean, and resembles not only other temperate rain forests worldwide, but also the montane evergreen Afromontane forests that occur at higher elevations in southern and eastern Africa. A fine example of this forest is in South Africa's Tsitsikamma National Park.
[edit] New Zealand temperate rain forests
The temperate rain forests of New Zealand occur on the western shore of New Zealand's South Island and on New Zealand's North Island. The forests are made up of coniferous podocarps and broadleaf evergreen trees; the podocarps are dominant at lower elevations, while southern beech (Nothofagus) becomes dominant on higher slopes and in the cooler southernmost rain forests. Ecoregions include the Fiordland temperate forests and Westland temperate forests.
[edit] Australian temperate rain forests
Western Tasmania is home to the Tasmanian temperate rain forests ecoregion. Low elevation rainforests on fertile soils are predominantly broadleaf evergreen forests dominated by Myrtle Beech (Nothofagus cunninghamii) and Southern Sassafras (Atherosperma moschatum). Rainforests on poorer soils, higher elevations, and riparian rainforests are mixed forests with tasmanian endemic conifers, like Huon Pine (Lagarostrobos franklinii), and King Billy Pine (Athrotaxis selaginoides).[3] Temperate rainforests also occur in Victoria's Otway Ranges, the Strzelecki Ranges, Dandenong Ranges, East Gippsland and eastern New South Wales, with the northern most extent of cool temperate rainforest occurring on the NSW/QLD border in the World Heritage listed Border Ranges National Park and Lamington National Park.
[edit] Colchian rain forests
The Colchian rainforests are found around the southeast corner of the Black Sea in Turkey and Georgia and are part of the Euxine-Colchic deciduous forests ecoregion, together with the drier Euxine forests further west. The Colchian rain forests are mixed, with deciduous alder, hornbeam, Oriental Beech (Fagus orientalis), and chestnut together with evergreen Nordmann Fir (Abies nordmanniana, the tallest tree in Europe at 78m), Caucasian Spruce (Picea orientalis) and Scots Pine (Pinus sylvestris).
[edit] Taiheiyo (Pacific) evergreen rain forests
Southwestern Japan's Taiheyo Evergreen Forests region covers much of Shikoku and Kyūshū Islands, and the Southern/Pacific Ocean-facing side of Honshu ("Taiheiyo" is the Pacific Ocean, in Japanese). Only small portions of this are considered rainforest, with some of the best examples of forest found in Kirishima-Yaku National Park on the Island of Yakushima off of Kyūshū. Other areas include Mount Kirishima near Kagoshima in southern Kyūshū. On Southern Honshū, there is a splendid forest with the beautiful Nachi Falls located in Yoshino-Kumano National Park. This particular area of Honshu has been described as one of the rainiest spots in Japan.
[edit] Taiwan's mountain coniferous rain forests
These forests are found in eastern Taiwan and Taiwan's Central Mountain Ranges, part of the Taiwan subtropical evergreen forest region covering the higher elevations. Although most of the lower elevations are subtropical broadleaf evergreen, higher elevations give way to some fine temperate forests with large stands of old growth Taiwan cypress, camphor, maple, yew, hemlock, and Taiwan Douglas-fir. Some fine examples of forests are found in Yushan (Jade Mountain) National Park and Alishan.
[edit] Northwest Europe
Temperate rainforest occurs in fragments across the west of Britain, Ireland, Brittany, southern Scandinavia and northern Spain. They mainly consist of oak species, typically Quercus petraea and have been managed by humans for centuries. The woodlands are variously referred to in Britain as Upland Oakwoods, Atlantic Oakwoods, Western Oakwoods or Temperate Rainforest. They are also listed in the British National Vegetation Classification as British NVC community W11 and British NVC community W17 depending on the ground flora.
[edit] Appalachian temperate rain forests
Temperate rain forests in the eastern United States are limited to areas in the southern Appalachian Mountains where orographic precipitation causes weather systems coming from the west and from the Gulf of Mexico to drop more precipitation than in surrounding areas. The largest of these forest blocks are located in western North Carolina[4], northern Georgia[5], and far eastern Tennessee[6], largely in the Pisgah, Nantahala, Chattahoochee National Forests and nearby Gorges State Park[7]. In addition, small areas in the highest elevations of the Great Smoky Mountains also receive substantial rainfall, with Clingmans Dome, for example, collecting about 2000 mm of precipitation per year[8]. Although the highest summits of the Green Mountains of Vermont[9], the White Mountains of New Hampshire[10], and Mount Katahdin in Maine[11] receive over 2000 mm of precipitation per year, some of these locations have alpine environments and whether or not temperate rain forests exist in these regions is subject to debate. It is possible for small blocks of temperate rainforest to exist along the slopes of these mountain ranges below the tree line where annual precipitation is sufficient for such forests to thrive.
[edit] Southern ocean island temperate rain forests
The islands of the Tristan da Cunha group and New Zealand's southern outlying islands of the Antipodes Islands, Auckland Islands, and Campbell Island group all host temperate rain forests. Annual rainfall totals are high due to the lack of landmass in their latitudes. Some areas of these islands are too windy for forests, but those areas that are not as windy are capable of growing temperate rain forests. The only thing preventing the Falkland Islands from having temperate rain forest is the proximity of the very high Andes Mountains to the west.
[edit] References
- ^ Northern Wetbelt - University of Northern British Columbia http://wetbelt.unbc.ca/
- ^ Di Castri F di & E. Hajek 1976. "Bioclimatología de Chile" 163 pages with english summary
- ^ Reid et al. Vegetation of Tasmania. 2005.
- ^ Average Annual Precipitation North Carolina. Oregon State University (2000). Retrieved on 2006-02-23.
- ^ Average Annual Precipitation Georgia. Oregon State University (2000). Retrieved on 2006-02-23.
- ^ Average Annual Precipitation Tennessee. Oregon State University (2000). Retrieved on 2006-02-23.
- ^ Jocasse Gorges. Learn NC (2000). Retrieved on 2006-02-23.
- ^ Smoky Mountains Weather. National Park Service. Retrieved on 2006-02-23.
- ^ Average Annual Precipitation Vermont. Oregon State University (2000). Retrieved on 2006-02-23.
- ^ Average Annual Precipitation New Hampshire. Oregon State University (2000). Retrieved on 2006-02-23.
- ^ Average Annual Precipitation Maine. Oregon State University (2000). Retrieved on 2006-02-23.
[edit] External links
- The Rainforests of Home, an atlas of People and Place - from Inforain
- Teacher Pages: Temperate Rainforest (Wheeling University)
- Southeast Alaska Conservation Council - preserving rainforests in Southeast Alaska
- Raincoast - preserving rainforests in coastal British Columbia's Great Bear Rainforest
- The Warm and Cool Temperate Rainforests of Australia
- Temperate Rainforests of North America's Pacific Coast
- British Columbia's Rainforests Essays by Elmer G. Wiens]
