ECOLOGY OF PACIFIC YEW (TAXUS-BREVIFOLIA) IN WESTERN OREGON AND WASHINGTON

Taxus brevifolia, a subcanopy tree or shrub in forests of the Pacific Northwest, has been harvested intensively in recent years. With manage ment concerns as an impetus, we examined the distribution and populati on dynamics of Taxus based on data from the mountains of western Orego n and Washington. Surveys of natural forests, long-term studies of for est recovery following logging, and census data on marked trees in for est stands support the hypothesis that Taxus is a widespread but predo minantly late-successional species. Sensitive to fire and slow to reco ver from disturbance on many sites, Taxus attains maximal basal area a nd adult stem density in old forests. Colonization of Taxus is often s low in potentially suitable habitats. Conservation of Taxus at the lan dscape level may require large, unmanaged reserves and maintenance of patches of old forest within managed forests. Long rotations (centurie s) between harvest events will enhance the long-term viability of the species. Practices designed to accelerate the development of old-growt h forest structure will not benefit Taxus and other species requiring long disturbance-free intervals for recovery.