Abstract:

In 1983, 1-0 container-grown Douglas-fir (Pseudotsuga menziesii) seedlings were planted on a site subject to summer drought under three levels of sprout competition from greenleaf manzanita (Arctostaphylos patula) and canyon live oak (Quercus chrysolepis). Seedlings were planted with 0.25-m-tall dead sprouts, mature shrubs slashed just before planting, or 1-m tall sprouts, which represent an increasing order of competition. After 3 years, Douglas-fir survival did not differ significantly among levels of competition. However, percentage cover of competing shrubs was negatively correlated with conifer root and shoot biomass. Under the least competition, root biomass increased 25 times and shoot biomass 103 times over dry weight at planting, but dry weights in other treatments increased <5 times. Douglas-fir seedling growth did not increase significantly following shrub removal when vigorous sprouting occurred during the first year. After 3 years, however, competitor cover in the minimum-competition plots was less than 15%, and conifer biomass had increased exponentially. West. J. Appl. For. 4(3):89-92, July 1989.

Document Type: Journal article

Affiliations: 1: Department of Forest Science, College of Forestry, Oregon State University, Corvallis, OR 97331