Antelope Bitterbrush Seed Production and Stand Age

Antelope bitterbrush (Purshia tridentata (Pursh) DC) is the most important browse species on many western mule deer (Odocoileus hemionus) ranges. Lack of antelope bitterbrush seedling recruitment is a critical problem, and therefore, the influence of livestock grazing on antelope bitterbrush seed production is an important issue. Seed production was compared in grazed and ungrazed communities during 1995 and 1996 at 2 locations in northeastern California and one location in northwestern Nevada. A system of seed traps was used to estimate seed production in relation to the size, age and grazing of antelope bitterbrush plants in the various stands. Antelope bitterbrush seed production was significantly (P less than or equal to 0.01) higher at one of the ungrazed sites. Significant (P less than or equal to 0.05) differences in shrub ages were also recorded between sites.