Thinning Decreases Mortality and Increases Growth of Ponderosa Pine in Northeastern California

摘要

Overstocked 70-to 90-year-old stands of ponderosa pine on medium-to low-quality sites were thinned in 1980 to 40, 55 and 70 percent of normal basal area and compared to an unthinned control. Mortality, diameter, and height in these northern California stands were measured annually from 1980 to 1987. After 8 years, mortality, primarily from mountain pine beetle (Dendroctonus ponderosae) and annosus root disease (Heterobasidion annosum) was reduced 100, 95, and 86 percent relative to increasing amounts of reserve basal area. Thinned stands averaged five times more cubic-foot volume growth than unthinned stands. More growth and less mortality could result from treating similar stands elsewhere.