Vegetation trends in a young conifer plantation after grazing, grubbing, and chemical release

Abstract

A 3-year-old Jeffrey pine (Pinus jeffreyi Grev. & Balf.) plantation in northern California was released by grazing with sheep for 5 years, manual grubbing for 3 years, and applying a herbicide 1 year. These treatments plus an untreated control provided an opportunity to evaluate density and developmental trends for the pine, shrub, and grass components of the plant community during 1986-1994. Creating a near free-to-grow condition by applying Velpar herbicide modified the plant community by controlling the shrubs, reduced cheatgrass in the second and third years, and caused mean pine diameter, foliar cover, and height to be significantly greater than counterparts in all other treatments. Grazing caused two significant, but opposing changes in the plant community. Nipping of twigs by sheep stimulated foliar cover of snowbrush to more than three times that of similar plants in the control. Grazing significantly reduced greenleaf manzanita cover. Grubbing a 4-foot radius around pine seedlings, and grazing with sheep did not increase Jeffrey pine development relative to the control. Because of this ineffectiveness, the efficacy of grazing as a silvicultural tool is questioned and suggestions for its betterment are presented.

Citation

McDonald, Philip M.; Fiddler, Gary O.; Meyer, Peter W. 1996. Vegetation trends in a young conifer plantation after grazing, grubbing, and chemical release. Res. Paper PSW-RP-228-Web. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 17 p