Western Hemlock tree broken by wind

Western Hemlock is the most abundant tree species in Southeast Alaska.
Western Hemlock is the most abundant tree species in Southeast Alaska.

Western Hemlock is the most abundant tree species in Southeast Alaska. It can reach an age of over 1,200 years, a height greater than 70 m (230 feet), and a diameter over 2.7 m (9 feet).

Wind is the primary cause of disturbance in the Pacific Coastal Temperate Rainforest of Southeast Alaska. Wildfires are infrequent and generally small due to the high rainfall, which ranges from 127 cm (50 inches) to over 508 cm (200 inches) per year.

Windthrown Old-growth Hemlock
Windthrown Old-growth Hemlock


Storms can windthrow large patches of timber, but in old-growth forest (generally over 300 years old), most openings are very small, averaging less than 0.8 hectares (2 acres). With small openings, the pattern of trees in mature forest is a mixture of sizes and ages.

The Western Hemlock tree in the photo has been broken by wind. Because bedrock is close to the surface resulting in thin soils and shallow roots, trees often are uprooted by the wind. Since this tree broke, we know its roots were strong.

It’s easy to focus only on the beautiful green forest of living trees when we walk in the woods. But both standing dead trees and logs on the ground are extremely important ecological parts of the forest.

Many wildlife species depend on dead wood for food, shelter, nesting, perching, and escape from predators. As you hike through the forest, take time to observe the many forms of dead wood. Look for the evidence of use by wildlife.
Like so many of the features of the forest, the values of dead wood also create high quality fish habitat.

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William Arthur Hanson (Bill Hanson) is an Alaskan writer who searches for the roots of life in landscapes and the inhabitants they shape. He draws on 30 years as a biologist, forester, and ecologist. He has worked from the rainforests of Southeast Alaska to the subarctic taiga of the Interior. His writing mixes his deep knowledge of Alaska with people and places from his worldwide travels to Vietnam, Russia, Mexico, Ecuador, Europe, Malaysia, and much of the United States.

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