E-Flora BC: Electronic Atlas of the Flora of British Columbia

Xanthocyparis nootkatensis (D. Don) D.P. Little
yellow-cedar (Alaska cedar; cypress)
Cupressaceae (Cypress family)

Introduction to Vascular Plants

© Kevin Newell  Email the photographer   (Photo ID #1346)

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Distribution of Xanthocyparis nootkatensis
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Species Information

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Tree, usually 20-40 m tall when mature; branches and branchlets droop strongly; bark ridged and fissured, not tearing off in long thin strips; wood aromatic (potato-like smell); growing "tip" (leader) drooping.
Scalelike, opposite, somewhat overlapping, close to stem, with sharp, rigid tip; bluish green.
Seed cones like a round, bumpy light green "berry" when immature, brown when ripe, less than 10 mm long, glaucous; pollen cones about 4 mm long.

Source: The Illustrated Flora of British Columbia

Habitat / Range

Habitat/Range: Wet to mesic slopes and bogs in the lowland, montane and subalpine zones; common in and W of the Coast-Cascade Mountains, rare in SE BC; N to SE AK and S to N CA.

Source: The Illustrated Flora of British Columbia

Additional Notes

For over two decades, the phenomenon of yellow-cedar decline has perplexed researchers. Yellow-cedar (Chamaecyparis nootkatensis) (D. Don) Spach), which ranges from southern Oregon to Prince William Sound, Alaska, was known to be declining on over 200,000 ha of undisturbed forest in southeast Alaska (Snyder et al. 2008). During an aerial survey in 2004, numerous large areas of dead and dying yellow-cedar were found in coastal locations in B.C., and the nature of the dieback was found to be consistent with the phenomenon in southeast Alaska (Hennon et al. 2005).

Research into the decline of this long-lived species began in the early 1980s and a sequence of symptoms was identified. The initial symptom was determined to be fine root death, followed by death of small-diameter roots (Hennon et al. 2006) (PDF). As the roots start to die, the trees develop thin off-colour crowns, and necrotic lesions spread from larger roots up the bole (Hennon et al. 2006). The natural resistance of yellow cedar heartwood to decay allows dead trees to remain standing for 80 to 100 years after death. By examining the standing snags it was possible to establish that the decline of yellow-cedars began in about 1880-1900 (Hennon & Shaw, 1997).

Investigations initially focused on finding a biotic cause of the decline, but one by one the suspected agents were ruled out (Hennon et al. 1990). Attention then shifted to abiotic factors potentially associated with the decline, and an association with wet, poorly drained soils was found. However, the relation with soil drainage was inconsistent, with limited decline occurring on wet sites at higher elevations (Hennon et al. 2006). Air and soil temperature were determined to be stronger risk factors than poorly drained soils (D'Amore & Hennon, 2006).

These clues led researchers to propose a new, complex hypothesis to explain yellow-cedar decline. According to Hennon et al. (2006), saturated soils create open, exposed canopies that experience soil warming early in the spring. This warming triggers the yellow-cedars to lose their cold tolerance, making them more susceptible to freezing injury. Snow appears to protect yellow-cedar against this freezing injury by preventing soil warming. However, the end of the Little Ice Age, which coincided with the onset of decline, has led to a reduction in snowpack at lower elevations (Hennon et al. 2006). This shift in climate may represent the environmental trigger responsible for the decline and suggests that the dieback may expand if warming trends continue (Hennon et al. 2006).

Note Authors: Claire Wooton and Brian Klinkenberg

Synonyms and Alternate Names

Callitropsis nootkatensis (D. Don) Oerst. ex D.P. Little
Chamaecyparis nootkatensis (D. Don) Spach
Cupressus nootkatensis D. Don

Taxonomic and Nomenclatural Links

Additional Photo Sources

Species References

BC Ministry of Forests and Range. 2010. Yellow-cedar. In: The Tree Book: Learning to Recognize the Trees of British Columbia. BC Ministry of Forests and and Range, Victoria. Available online.

Gadek, P. A., Alpers, D. L., Heslewood, M. M., & Quinn, C. J. 2000. Relationships within Cupressaceae sensu lato: a combined morphological and molecular approach. American Journal of Botany 87: 1044–1057.

Farjon, A., Hiep, N. T., Harder, D. K., Loc, P. K., & Averyanov, L. 2002. A new genus and species in the Cupressaceae (Coniferales) from northern Vietnam, Xanthocyparis vietnamensis. Novon 12: 179–189.

Little, D. P., Schwarzbach, A. E., Adams, R. P. & Hsieh, Chang-Fu. 2004. The circumscription and phylogenetic relationships of Callitropsis and the newly described genus Xanthocyparis (Cupressaceae). American Journal of Botany 91 (11): 1872–1881.

Michener, David C. Chamaecyparis nootkatensis. Flora North America Online. Available online.

Mill, R. R. and Farjon, A. (2006). Proposal to conserve the name Xanthocyparis against Callitropsis Oerst. (Cupressaceeae). Taxon 55(1): 229-231.

General References