About Temperate Rainforests

Definition – the world’s coastal temperate rainforests are geographically restricted to just seven regions: British Columbia, Alaska, Chile, New Zealand, Pacific Northwest USA, Australia, and western Europe. These forests are heterogenous and vary considerably within individual regions as well as from one region to the next making broad characterizations difficult. However, coastal temperate rainforests owe their physical and ecological characteristics to the influence of oceanic currents, weather patterns, and coastal landmasses. Characteristics that are commonly shared among coastal temperate rainforests are as follows:

• Coastal distribution (<150 km to the coast)
• High annual precipitation (>80 inches, 2,000 mm)
• Precipitation spread over 100 days seasonally with 10% during the summer
• Cool overcast summers, relatively snow free winters (low elevation)
• Latitudinally restricted – southern hemisphere: 38 –56 degrees South; northern hemisphere: 38-61 degrees North
• Disturbance is typically gap-phase (canopy mortality), blow down from storms, and avalanches – fire is generally not a major factor - at least 100 years between stand-replacing fires (with the exception of the coastal redwoods of Northern California where fire occurs more frequently)

In the northern hemisphere, coastal temperate rainforests are dominated by coastal conifers such as Sitka spruce and western hemlock. Further north, these species give way to mountain hemlock that eventually is replaced by tundra and boreal forests. Coastal temperate rainforests in this region are also know as the Great Bear-Salmon rainforests for the keystone role these species play in forest ecosystems. Salmon, in particular, reflect the interconnectedness of marine, freshwater, and terrestrial environments, a key characteristic of coastal temperate rainforests. These species also are a vital part of the cultural heritage and subsistence use of Native Alaskans.

In the southern hemisphere, Chile’s Valdivian ecoregion contains about 20% of the world’s coastal temperate rainforests. Spanning about 1,600 km, this region has exceptional plant richness for its southerly latitude, including many relict genera with Gondwanaland affiliations. Approximately 1/3 of plant genera in this region has Gondwanaland affiliations, while another 1/3 of the woody plants and ¼ of the vascular plants are endemic to the region. The region is also home to numerous taxa with high rates of endemism, including amphibians (76% endemic), freshwater fishes (50%), reptiles (36%), mammals (33%), and birds (30%).

Conservation Status and Importance – collectively, the world’s coastal temperate rainforests perform many vital ecosystem services of regional and global importance, including carbon sequestration (especially the long-term carbon storage in old-growth forests), intact watersheds, super-abundant fish and wildlife populations, and unique species and plant assemblages. However, only a few regions have watersheds that are still intact and have not been fragmented by logging or road building. For instance, sections of British Columbia’s coastal forests (north of Vancouver Island) and portions of southeast Alaska collectively make up the “Amazonia” of temperate rainforests, where 50% of the world’s temperate rainforest occur and many watersheds are still intact. The following describes a break down by amount of rainforest, degree of intactness (no logging) and level of protection by geographic region.

In sum, coastal temperate rainforests are rare globally, restricted to just 7 regions of the world. In many ways, coastal temperate rainforests are at least as important as the world’s tropical rainforests. More than ½ the world’s coastal temperate rainforests have been fragmented by logging and road building. In some regions (e.g. Western Europe), coastal temperate rainforests have been completely eliminated while in others they barely hang on (e.g., Oregon, USA). Even in regions having intact watersheds (BC, Alaska – “Amazonia” of temperate rainforests), logging and road building are beginning to unravel the Great Bear-Salmon rainforests.

International conservation attention is urgently needed to protect the last of the world’s coastal temperate rainforests, raise awareness about their global rarity and importance, promote restoration, and encourage sustainable forest management practices.

Dominick A. DellaSala, Ph.D
Director World Wildlife Fund’s Klamath-Siskiyou Program
Ashland, OR

For more information on coastal temperate rainforests, see:

The Rainforests of Home: An Atlas of People and Place

Canada’s Great Bear Rainforest

Alaska’s Rainforest

Tarkine Rainforest, Tasmania

Valdivian Rainforest, Chile

Inland Temperate Rainforest, BC

BOOK: The Rainforests of Home: Profile of a North American Bioregion. Edited by Peter K. Schoonmaker, Bettina von Hagen, and Edward C. Wolf. Washington, DC: Island Press, 1997.