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 management concerns as an impetus, we examined the distribution and population dynamics of Taxus based on data from the mountains of western Oregon and Washington. Surveys of natural forests, long-term studies of forest recovery following logging, and census data on marked trees in forest stands support the hypothesis that Taxus is a widespread but predominantly late-successional species. Sensitive to fire and slow to recover from disturbance on many sites, Taxus attains maximal basal area and adult stem density in old forests. Colonization of Taxus is often slow in potentially suitable habitats. Conservation of Taxus at the landscape level may require large, unmanaged reserves and maintenance of patches of old forest within managed forests. Long rotations (centuries) between harvest events will enhance the long-term viability of the species. Practices designed to accelerate the development of old-growth forest structure will not benefit Taxus and other species requiring long disturbance-free intervals for recovery.