Release of Douglas-fir seedlings: growth and treatment costs

Abstract

Foresters often lack information on growth of woody shrubs and their effect on conifer seedling survival and growth. Deerbrush (Ceanothus integerrimus H. & A.) was treated by several manual and chemical methods at age 3 and again at age 5 in a Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) plantation on a medium-quality site on the Klamath National Forest, California. Four years after initial release, Douglas-fir stem caliper at 12 inches (30 cm) above mean ground line differed significantly (0.69 ± 0.30 inch or 1.75 ± 0.76 cm) between an entire area (one-seventh acre) sprayed directly with 2, 4-D and the untreated control. Additional analyses with combinations of treatment means indicated significant differences in Douglas-fir seedling survival and stem caliper among three manual and an additional chemical treatment. Differences among the six treatments, which are presented in 15 comparisons of stem caliper and treatment production rates, provide forest managers with growth and cost comparisons.

Citation

McDonald, Philip M.; Fiddler, Gary O. 1986. Release of Douglas-fir seedlings: growth and treatment costs. Res. Pap. PSW-RP-182. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. 9 p.