Callitropsis nootkatensis , yellow-cedar

This review summarizes the information that was available in the scientific literature as of 2025 on the biology, ecology, and effects of fire on yellow-cedar in North America. Yellow-cedar is a native, evergreen, long-lived tree that occurs along the Pacific Coast of North America from southeastern Alaska to northern California, with two relict populations occurring farther inland. It occurs from sea level to treeline in the northern part of its range and occurs at increasingly high elevations in the southern part. Yellow-cedar requires a cool, humid climate and occurs most commonly in areas with short growing seasons and perennial moisture availability. It usually occurs singly or in scattered clumps intermixed with other tree species, and only occasionally grows in pure stands. Its size and growth form differ among sites, ranging from short-statured and shrublike forms at the highest elevations and harshest sites, to very large trees in more productive sites. It is a common to codominant component of plant communities with differing stand structures, including short-statured and open-canopy forested wetlands; tall, closed-canopy coastal rainforests; and subalpine forest patches with large trees, dwarfed trees, or krummholz. Yellow-cedar reproduces by seed and by layering. Layering occurs mostly in wetlands, subalpine sites, and in avalanche tracks, where heavy snow loads force its flexible stems and branches to contact soil. Seedling establishment and recruitment are rare to infrequent and sporadic on most sites because seed production is irregular, seed viability and germination rates are low, and seedlings often die. Yellow-cedar trees can be long-lived, with age estimates exceeding 1,500 years. Information on yellow-cedar’s fire adaptations and response to fire is limited, largely because it occurs in plant communities with rare to infrequent fires. It is considered to have a low tolerance to fire and is not expected to survive even low-intensity fires due to its thin bark and shallow roots. Nonetheless, fire-scarred individuals have been documented, especially in the relict, inland stand, which is surrounded by a dry mixed-conifer forest with a history of frequent, low-intensity fires. Yellow-cedar does not regenerate vegetatively after fire. It may establish from seed after fire on some sites, depending on available seed sources, plant community composition, site characteristics, and postfire weather. Extensive yellow-cedar mortality in southeastern Alaska and adjacent British Columbia—yellow-cedar decline—is a widespread and long-term management concern that is caused by interrelated factors driven largely by climate change and its effects on winter snowpack.