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Temperate rainforest

Forests in the temperate zone

  • 21 min read
  • 3 chapters
Windy Bay forest in Gwaii Haanas National Park Reserve
Sam Beebe · CC BY 2.0

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Through Forest, Temperate climate and North America

Temperate rain forests occur in oceanic moist regions around the world: the Pacific temperate rain forests of the North American Pacific Northwest as well as the Appalachian temperate rain forest in the Appalachian region of the United States; the Valdivian temperate rain forests of southwestern South America; the rain forests of New Zealand and southeastern Australia; northwest Europe (small pockets in Great Britain and larger areas in Ireland, southern Norway, northern Iberia and Brittany); the Eastern Korea-Manchuria continuum; Japan; the Black Sea–Caspian Sea region from the southeasternmost coastal zone of the Bulgarian coast, through Turkey, to Georgia, and northern Iran.

The moist conditions of temperate rain forests generally have an understory of mosses, ferns and some shrubs and berries. Temperate rain forests can be temperate coniferous forests or temperate broadleaf and mixed forests.

Definition

For temperate rainforests of North America, Alaback's definition is widely recognized:

  • Annual precipitation over 140 cm (55 in) (KJ)
  • Mean annual temperature is between 4 and 12 °C (39 and 54 °F).

However, required annual precipitation depends on factors such as distribution of rain over the year, temperatures over the year and fog presence, and definitions in other regions of the world differ considerably. For example, Australian definitions are ecological-structural rather than climatic:

  • Closed canopy of trees excludes at least 69% of the sky.
  • Forest is composed mainly of tree species which do not require fire for regeneration, but with seedlings able to regenerate under shade and in natural openings.

Australian definitions would exclude some temperate rainforests of western North America that are Coast Douglas-fir dominant, such as parts of the Klamath Mountains in southern Oregon and northern California, the Puget Lowlands of western Washington and the Georgia Depression in British Columbia, as their dominant tree species, the Coast Douglas-fir, requires stand-destroying disturbance to initiate a new cohort of seedlings. The North American definition would in turn exclude a part of temperate rainforests under definitions used elsewhere.

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