Introduction. Rainforests of the mid-latitudes exist in both the Northern and Southern hemispheres. The largest area is found along the Pacific coast of North America from California north through British Columbia into Alaska. At the northern extreme it transitions into a boreal rainforest. An inland band of western rainforest, separated from the coastal communities, stretches along the Columbia and Rocky mountains. Some authors identify the coniferous forests of the Atlantic coast of eastern Canada from Nova Scotia to southern Labrador, on Newfoundland, and in the mountains of eastern Quebec as temperate and boreal rainforest. Elsewhere in the Northern Hemisphere, mid-latitude rainforest can found in Japan and Korea. Relict patches of temperate rainforest survive in Europe, in the Alps, Great Britain, Iceland, Ireland, and Norway. Temperate rainforest borders the Pacific Ocean in southern Chile and Argentina. Covering an area less than half the size of the North American Pacific coast rainforests, the largest expanse is the Valdivian rainforest, the norrthernmost (37°45′ S─43° 20′ S) of three rainforests and the most species-rich. It abuts the Northern Patagonian rainforest (43° 20′ S─47° 30′ S). Southernmost is the Magellanic rainforest, extending southward from 47° 30′ S into Tierra del Fuego . Other significant Southern Hemisphere rainforests grow in Australia and New Zealand. Northern Hemisphere forests are all composed of the same genera of needleleaf trees in the pine family: Abies (firs), Picea (spruces), Pinus (pines) Thuja (cedars), and Tsuga (hemlocks). They tower above a dense understory of broadleaf shrubs and herbs and a thick ground layer of ferns, mosses, and liverworts. Lichens growing on rocks, fallen logs, and tree trunks and hanging from tree branches are abundant and species-rich. In the Southern Hemisphere, broadleaved evergreens emerge above a many-layered understory of both evergreen and deciduous trees and shrubs. In the South American forests the genus Nothofagus (southern beeches) dominates. Other Gondwanan genera also occur there and in Australia and New Zealand, but most species are restricted to a particular continent. The pine family is completely absent from the Southern Hemisphere, but Cupressaceae (cypresses), an ancient family that was in existence before the breakup of Pangea, is represented in both hemispheres. Southern Hemisphere temperate rainforests evolved in isolation from northern hemisphere mid-latitude expressions of the biome. They instead exhibit evolutionary ties to tropical species, and as a consequence most trees produce edible fruits and rely upon animal pollinators and seed dispersers. Some of the world’s tallest trees grow in temperate rainforests. Douglas fir (Pseudotsuga menziesii var. menziesii) and coast redwoods (Sequoia sempervirens) in North America attain heights of more than 325 ft. as does mountain ash (Eucalyptus regnans) on Tasmania, Australia. Alerce or Patagonian cypress (Fitzroya cupressoides) in the Valdivian forest of Chile and Argentina in the 19th and 20th centuries, before widespread logging, reportedly also grew this tall. Temperate rainforests everywhere are threatened by deforestation and climate change. Climate. Cool, moist marine west coast climates are associated with temperate rainforests growing in coastal areas. These climates are marked by a low annual temperature range with both summers and winters being relatively mild. Inland northwestern North American and eastern Canadian forests are influenced by continentality and experience greater temperature extremes, particularly in winter when snows may be deep. Coastal areas in the high latitudes also receive snow. Precipitation is year round, though much is concentrated in the autumn and winter months. Fourteen to 25 percent of annual precipitation occurs during the three driest months, enough to maintain a definitely humid climate type. Even so seasonality is sufficient to affect fire regimes, species composition—including abundance of epiphytes, and drought tolerance. Total annual amounts vary widely, due in part to the great latitudinal extent of the Pacific coast forests of both hemispheres. Recorded totals range from 33−220 inches a year. Soils. A deep humus layer with large amounts of woody debris develops in these forest and only slowly decomposes. It is rich in invertebrates and supports extremely diverse macrofungi (mushrooms). Nutrient cycles in coastal forests are linked to the sea by fish-eating birds (e.g., marbled murrelet) as well as bears and sometimes wolves that feed heavily on salmon migrating upstream to spawn, as in the Great Bear Rainforest of British Columbia, Canada). A “pit and mound” microtopography often develops on the forest floor. The pits result from holes left by uprooted trees (windthrows); the mounds are hummocks formed by slowly decaying logs, other woody debris, and roots cloaked in a dense covering of mosses, liverworts, and ferns. Vegetation. Since plant life in the various temperate rainforests differs from continent to continent and even on the same continent, vegetation and other details specific to each major region will be discussed on separate pages. See: North America South America Australia Main source: Dominick A. DellaSala, editor. 2011. Temperate and Boreal Rainforests of the World: Ecology and Conservation. Island Press.
They are found along the Pacific coast of North America from Alaska south through Canada to California. Though disappearing around the world they are also found in South America, Scandinavia, New Zealand, Ireland, and Scotland.
When you think of a rainforest, do you picture monkeys, parrots, and huge, coiled snakes? Not all rainforests are tropical. The temperate rainforests on the west coast of North America are very different from the tropical rainforests of South America. Temperate rainforests have a long growing season, though unlike tropical rainforest they do have a change of seasons. Temperatures change from 80°F in summer down to near freezing in winter. The cooler temperatures mean that temperate rainforests have less diversity than tropical rain forests. (This means that there are fewer types of animals and plants found there.) This doesn’t mean though that things don’t grow there. These are among the most productive forests in the world. Temperate rainforests have lots of rainfall (sometimes up to 200 inches a year!) but also have cool, moist air in the form of ocean fog keeping things wet. Temperate rainforests have fertile soil. This is a result of all the dead materials rotting into the soil. Decomposing matter releases nutrients back into the soil and is good for growing thick stands of fast growing trees. Trees grow tall here – sometimes over 250 feet and their trunks can reach 15 feet across. Some of these trees can live for 500 years! Because of this, the temperate rainforests have been heavily timbered (trees are cut for lumber products). For a high resolution PDF for printing, scroll to the bottom of the page.
Unlike tropical rainforests where much of the animal life lives up in the trees, (some never coming to the forest floor at all), in the temperate rainforest, most animals live on or near the ground. Crossbills use their scissor-like beak to pry seeds from cones, while mule deer and red tree vole feed on young conifer needles. Porcupines and snowshoe hare feed on conifer bark in winter while black bears stuff themselves with berries in the fall. In addition to seeds, deer mice and Townsend’s chipmunk eat mushrooms that grow well in the wet environment. Other animals found in temperate rainforests include; raccoon, bobcat, mountain lion, mountain beaver, mink, Pacific giant salamander, shrews, pine sisken, and great horned owls.
Most of the trees in the temperate rainforests of the Pacific Northwest are conifers. The dominant tree is the Douglas fir. It is one of the tallest trees and is considered one of the most important trees to the timber industry. Further south where heavy rains give way to ocean fogs, the great redwoods grow. Other trees that grow in these forests include western hemlock, Sitka spruce, western red cedar, noble fir, and Pacific silver fir. Smaller trees include big leaf maple, dogwood, and vine maple. The forests are shady and damp and shade-loving underbrush thrives here, including Pacific rhododendron, blackberries, salmonberries and thimbleberries, sword ferns, devil’s-club, redwood sorrel, mushrooms, moss and lichens.
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The temperate rainforest is best described as
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