The regeneration of Pacific yew (Taxus brevifolia) in Douglas-Fir forests in northwestern California

In 1992 the rapidly developing demand for taxol led to consideration of a possible Pacific yew harvest in northwestern California. Deer browsing has prevented regeneration of Canada yew in some areas. Knowing that deer populations have been high in the past suggested that regeneration in Pacific yew may also be affected. I sampled two areas of yew on northern aspects. The northern stands were at 1020 m elevation on granitic and metasedimentary parent material near the Klamath River in Siskiyou County. The southern stands were at 700 - 900 m elevation on metasedimentary parent material near the South Fork of the Trinity River in Trinity County. I recorded heights, diameters, health, and degree of browsing for each yew. All sizes of yew were present at both northern stands. However, no yew between 3.0 and 5.2 cm basal diameter were found at the main southern stand and only two live and two dead yew were found between 0.95 and 9 cm basal diameter at the other southern stand. At both areas seedlings established during the drought. Comparisons between the main stands showed significantly more browsing on saplings (0.16 to 1.49 m tall) and a higher level of chlorosis in small seedlings at the southern stand than the northern one. Timing of peak deer populations and the size of the gaps in size distribution suggest that deer browsing caused these gaps. Browsing may still be strongly inhibiting recruitment to taller size classes.