Pacific Temperate Rainforests

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Yosemite National Park, California, United States of America.
© WWF-Canon / Edward PARKER

About the Area

This Global ecoregion is made up of 5 terrestrial ecoregions: Northern California coastal forests; Central Pacific coastal forests; Northern Pacific coastal forests; Queen Charlotte Islands; and British Columbia mainland coastal forests.

The Pacific Temperate Rainforests are amongst the richest and most diverse temperate forests on earth. They are one of only 7 temperate rain forest ecosystems, and the only one in North America.

Central Pacific coastal forests have the largest mass of both living and dead wood of any forests on Earth. Dead wood acts as habitat for an incredible variety of decomposers and other species.

More than a quarter of the world's coastal temperate rain forests occur in the North Pacific coastal forests ecoregion of southeast Alaska. With a unique combination of moderate temperatures and very high rainfall, the climate makes fires extremely rare. Instead, natural disturbances are caused by wind, landslides, avalanches, and floods.

Size:
295,000 sq. km (114,000 sq. miles)

Habitat type:
Temperate Coniferous Forests

Geographic Location:
North America: West Coast of United States and Canada

Conservation Status:
Critical/Endangered

Local Species
The ancient and spectacular redwood trees that dominate the Northern California Coastal Forests ecoregion are among the biggest, tallest, and oldest trees in the world. Many of these trees have been growing for more than 2,000 years, with some reaching heights of more than 90 meters (300 ft).

Lots of water makes these forests highly productive, harboring tree species such as Sitka spruce (Picea sitchensis), Yellow cedar (Chamaecyparis nootkatensis), Western red cedar (Thuja plicata), Western hemlock (Tsuga heterophylla), and Douglas fir (Pseudotsuga menziesii).

Selected species include the Pacific giant salamander (Dicamptodon ensatus), Olympic salamander (Rhyacotriton olympicus), red-backed vole (Cletherionomys californicus), red bat (Lasiuris borealis), spotted owl (Strix occidentalis), the ferocious folding-trap door spider (Antrodiaetus pugnax), and the marbled murrelet (Brachyrampus marmoratus) - birds that nest high up on redwood trees.

The Queen Charlotte Islands archipelago of more than 150 islands is a prime nesting area for bald eagles, tufted puffins, auklets, and thousands of other seabirds. Its black bear is the largest black bear in the world.

Featured species

The Pacific giant salamander, Dicamptodon ensatus, and its close relatives, are the largest of the salamanders that have a terrestrial stage. Adults measure 170 – 305 mm.

Giant salamanders have an interesting life cycle. They lay large clutches of sizable, yolky eggs under rocks in the headwaters of clear water streams. Eggs hatch after a several month incubation into stream-adapted larvae that have well developed limbs, a depressed body, and a tail fin that extends only to the base of the tail. The larvae live for at least 2 and perhaps as long as 4 years. They grow to a large size, some as large as the largest known adults. Occasionally larvae become reproductive, but more typically they metamorphose into the adult form.

Diet is most likely similar to related Pacific giant salamanders that feed on aquatic invertebrates, with a shift towards larger prey items with growth. Pacific giant salamanders have an arched posture and will release toxins when disturbed.

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Threats
Intensive commercial logging has destroyed more than 90% of the native forests of this ecoregion. The immense size of the mighty redwood trees, and the beauty of their wood, has made them a target for loggers for more than a century. Even logging in surrounding watersheds can have severe repercussions for redwood groves, since it can cause severe flooding, fires, and sedimentation. The spread of urban areas between Monterey and San Francisco, along with the introduction of exotic plants into these ancient forests, exacerbate the problems. Cruise ships can lead to pollution, as well as disturbing whales and other marine mammals. Other threats include pollution from pulp mills and mines.

Introduced beavers are also creating problems for native wildlife. Their damming of small streams is making it difficult for Coho salmon to travel upstream and spawn. Similarly, introduced rats, squirrels, and raccoons have reduced the size of seabird colonies as they prey on eggs and young birds.
WWF’s work
WWF works within the United States to safeguard wildlife, fisheries, forests, and wetlands. WWF is active in 6 US ecoregions, each home to a spectacular array of wildlife and plant species. More than three decades of international experience give WWF a unique perspective on the global importance of US biological resources and the conservation challenges facing the United States.

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Photos and graphics © WWF or used with permission. Text available under a Creative Commons licence.