Western Redcedar Dieback
Welcome to our webpage about the dieback of western redcedar. The purpose of this page is to provide information about the western redcedar, summarize the dieback, and provide links to other media expressing concern.
Please contact us if you are interested in partnering to advance knowledge or if you have content or information to share.
Icon of the Pacific Northwest
Western redcedar (Thuja plicata) is an iconic species of the Pacific Northwest because of its rich cultural value. Find more information and resources to learn about its incredible cultural heritage below.
The massive size of many trees throughout the region is testament to its capacity for long-term survival. Even after a tree has fallen, its bole can remain largely intact on the ground for centuries.
Western redcedar grows widely throughout our region because of its tolerance to shade, flooding and nutrient poor soils. However, recent observations of dieback and mortality have raised concern about its ability to cope with changes in the climate.
Links to More Information
- PNW Plants, WSU Clark County Extension
- USDA Plant Profile
- Woodland Trust
- Trees on the Trails, Washington Trails Association (PDF)
- Trees for Seattle, City of Seattle
- Native Plants PNW
- Natural Resources Canada
- The Jepson Herbarium
- E-Flora BC: Electronic atlas of the flora of British Columbia
Biology and Ecology
- Western redcedar (Thuja plicata), Washington State Department of Natural Resources
- Thuja plicata, The Gymnosperm Database
- False Cedars, Common Trees of the Pacific Northwest, Oregon State University
- Western redcedar, Government of British Columbia
- Index of Species Information, Fire Effects Information System, USDA Forest Service
- Western redcedar: ‘Tree of Life’, Oregon Department of Forestry
- Regional distribution, USDA Forest Service Southwest Research Station
- British Columbia distribution, Government of British Columbia
- Global distribution, iNaturalist
- United States distribution, Individual Tree Species Parameter Maps, USDA Forest Service
- Current and predicted range, Data Basin
- Native American Ethnobotany Data Base, University of Michigan
Relevant Pests and 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
- Cedar flagging, Pacific Northwest Pest Management Handbook, Oregon State University.
- Cedar flagging, Hortsense, Washington State University Extension.
- 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
The western redcedar is critically important to conserve because of its ecological, cultural and economic value.
Ecologically, it provides habitat and nourishment for many mammal and bird species and its tolerance to very wet soils allows it to flourish where other conifer species cannot.
Commercially, it is valued highly because of its durability and resistance to wood rotting fungi. It is also used widely in restoration activities locally and as an ornamental species internationally.
Culturally, western redcedar is considered a Cultural Keystone Species because its multiple uses and value to indigenous North American communities (read more below).
Western redcedar arguably has the richest cultural heritage of any plant species in the Pacific Northwest. Every part, from the roots to the tips of the boughs, can be crafted into useful products that were commonly used by ancient peoples of the Pacific Northwest. For example, foliage and boughs can be used as medicinal products, scented bathing materials, as ceremonial incense, or as rope for binding materials or creating fish traps.
Western redcedar is considered and Cultural Keystone Species because it is a fundamental component of many Northwest Coast cultures (Garibaldi and Turner 2004). These cultures rely on western redcedar for its medicinal properties, nutritional and dietary provisions, role in spiritual practices, and the materials it provides for warmth, shelter, and transportation. Given the clear importance of this is species, it is no wonder why western redcedar is commonly referred to as the ‘tree of life’.
Please contact us if you have any suggestions/corrections for this webpage.
More Cultural Heritage Resources
- Moerman DE. Native American ethnobotany. Timber press; 1998.
- Pojar J, MacKinnon A, Alaback PB. Plants of coastal British Columbia. Lone Pine Publishing; 1994.
- Stewart H, Cedar: Tree of Life to the Northwest Coast Indians, Douglas & McIntyre, University of Washington Press; 1995.
Publications and Reports
- Garibaldi, A., and N. Turner. 2004. Cultural Keystone Species: implications for ecological conservation and restoration. Ecology and Society 9.
- Klinka, K., and D. Brisco. 2009. Silvics and silviculture of coastal western redcedar: a literature review. Special Report Series – Ministry of Forests and Range, British Columbia.
- Hebda, R. J., and R. W. Mathewes. 1984. Holocene history of cedar and native indian cultures of the North American Pacific Coast. Science 225:711–713.
- Nelson, J. 2004. A Vanishing Heritage: The Loss of Ancient Red Cedar, David Suzuki Foundation.
Be careful not to confuse yellow cedar with western redcedar. Yellow cedar is best adapted for conditions in Alaska, but the range extends into Washington.
Port Orford Cedar
Port Orford cedar is another cedar that can be confused with western redcedar. This species is most abundant in coastal Oregon and northern California, but is commonly planted as an ornamental species.
Both species are also planted widely throughout the urban areas of cities such as Seattle.
Distinguish Western Redcedar
Western redcedars can be distinguished from other cedars by their erect egg shaped cones and the ‘butterfly’ shaped bloom on the underside of leaves.
Unfortunately, many reports of dieback have been noted during the past few years, ranging from Oregon to British Columbia (see below).
These reports generally note trees with thinning crowns, flagging, yellowing or browning of foliage, dying tops and mortality.
There is a general consensus among land managers, federal and state natural resource agencies, and WSU Extension Forestry specialists that the driver of the dieback is abiotic. Given its extent throughout the region, it is likely linked with recent drought events, but the relationship has not been empirically tested.
We recommend reading Melissa J. Fischer’s Blog Post (DNR): Western Redcedar East of the Cascades: A Species in Decline? for a thorough discussion of the issue and potential drivers.
- Portland Parks and Recreation, 2019. Urban Forest Health: western redcedar and drought, Urban Forestry, Tree Bark Number 1, August 2019.
- WSU Extension, 2018. Forester’s Notes – Western Redcedar, Washington State University, North Puget Sound Extension Forestry E-Newsletter, Volume 11, Number 2, July 2018.
- O’Neill E. 2019. ‘Dead tree after dead tree.’ The case of Washington’s dying foliage, KUOW, September 17, 2019.
- Vikander T. 2019. Western red cedars are dying of drought in Vancouver and scientists say it’s one more portent of climate change, The Star, Vancouver, June 13, 2019.
- Brend Y. 2019. Western red cedars die off as extended dry spells continue, say experts CBC News, May 14, 2019.
- Wilson C. 2018. Summer drought deals ‘devastating loss’ to western red cedar, B.C.’s official tree, Times Colonist, September 12, 2018.
- Fischer M. J. 2019. Western Redcedar East of the Cascades: A Species in Decline? Washington State Department of Natural Resources, Small Forest Landowner News, December 4, 2019.
- Rippey, C. 2018. Western redcedar die-off in Seattle Parks. Green Seattle Partnership, Restoration Resources, July 24, 2018.
- Pehling D. 2017. Sick looking Cedars? Washington State University, Gardening in Washington State Blog, October 16, 2017.
Did we miss any? Please contact us if you know additional reports or resources to add.
More research is needed
You can help research go faster by contributing to the Western Redcedar Dieback Map. Learn more about contributing to this project and the Forest Health Watch program at https://foresthealth.org/map
We are also actively pursuing opportunities to secure more support for research about the dieback of western redcedar. Please contact us if you’re interested in collaborating or supporting research about the dieback of western redcedar.
Observations of bark beetle and fungal associations with dead western redcedar trees have been shared, particularly in trees around Seattle. However, these associations are generally understood to be secondary, infecting the tree after it becomes stressed or dies. More research is needed to confirm or deny this consensus.
Help accelerate the research by sharing observations of healthy and unhealthy western redcedar trees. Join the Western Redcedar Dieback Map project and share your observations with us on iNaturalist.org. Find more instructions at https://foresthealth.org/map/.
Get Involved in the Forest Health Watch
The Forest Health Watch program hosts a visualization of the iNaturalist information here. The visualization updates every day.
The program also hosts monthly Research Update events on MS Teams. Register to attend a Research Update here.