Western Redcedar Ecology and Distribution

Ecology

Icon of Northwest Forests

Western redcedar is an important and unique component of northwest forests.

It has unmatched resilience to physical and biological disturbances, sometimes living more than a thousand years. Its durability and strength are impressive. For example, we often see mature trees with massive fire scars that have persisted many decades from tiny strips of living tissues.

Western redcedar is also cherished for its massive size, occasionally surpassing 200ft in height and 20ft in diameter!

Although many of these great giants are nearly impossible to age because of their great bulk and common heart rot, fallen trees can remain intact and persist in the habitat for hundreds of years (see Historical Image).

Habitat

Western redcedar is characteristically a tree of moist habitats and a natural resident of our temperate rainforests. It thrives in cool and wet climates where rainfall is heavy and supplemented by ample fog drip. In dryer conditions, further inland, it is more exclusively found in areas that escape fire and receive summer irrigation from mountain streams.

The species usually grows in mixtures with firs, hemlock, Douglas-fir, and broad leaf trees such as red alder, but it occasionally grows in pure stands on very wet soils where other conifer species do poorly.

Although western redcedar is a prolific seeder, it has low seedling survival. However, it can also reproduce vegetatively, where branches can become a new row of trees on a fallen tree or even take root after being pressed to the ground.

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Distribution

Western redcedar occurs from northern California to southern Alaska, and eastward through British Columbia to northern Montana. It thrives in temperate rainforest conditions and some of the biggest specimens exist on Vancouver Island and the Olympic Peninsula.

Western redcedar primarily grows between sea level and 3500ft in coastal forests, but reaches close to 5000ft in the mountains to the east. Apparently some trees have even been observed near the rim of Crater Lake at an elevation of 7500ft.

Pests and Disease

Insect Pests

Pests and disorders of Platycladus and Thuja spp., Statewide Integrated Pest Management Program, University of California.
Cedar bark beetle, University of British Columbia
Bark beetles of Cupressaceae, Department of Forest Protection, BFW, Federal Ministry Republic of Austria
Western cedar borer beetle, University of Britich Columbia

Disease

Root and heart rot fungi, Common Tree Diseases of British Columbia, Forestry Development, Natural Resources Canada
Cedar leaf blight, Pacific Northwest Pest Management Handbook, Oregon State University.
Cedar leaf blight, Hortsense, Washington State University Extension.
Cedar leaf blight, USDA Forest Service

Have you seen this fungus on a western redcedar?

Let us know by contacting us, submitting an unhealthy plant report, or adding an observation to the Western Redcedar Dieback Map.

Redcedar Habitat

Healthy Forests, Healthy Habitat

Western redcedar trees provide homes for many species. Many animals, including bears, often reside in hollow redcedars trees.

Interested in documenting the birds and mammals that occupy redcedar trees? Contact us about an upcoming project!

Adaptation

ASSISTED POPULATION MIGRATION

After identifying vulnerable areas and important environmental parameters, we can screen and select better adapted genotypes. For example, populations adapted to Oregon’s environmental conditions now may be better suited for future climates in Washington.

SEEDLOT SELECTION TOOL

The Seedlot Selection Tool is an incredible resource that can aid decisions when selecting seed sources for restoration. However, it is unclear which environmental parameters are the best predictors of success. Help us identify these parameters by mapping the areas where decline is occurring.

SEED COLLECTION

We are considering starting a collection that can be used for future research to screen populations. Contact us if you’re interested in helping collect seed from throughout its natural range.