Fire hazard from precommercial thinning of ponderosa pine.

Abstract

Precommercial thinning lately has become a major feature in management of ponderosa pine (Pinus ponderosa Laws.) on the National Forests in Oregon and Washington. Nearly 47,000 acres were thinned in 1966, up from 9,196 in 1959; and the upward trend appears certain to continue. Current practice is to cut the trees with a powersaw about a foot above the ground and let them lie as they fall. The slash, i.e., the felled trees, becomes a fire hazard as soon as it dries. It also obstructs access, provides a breeding place for certain insect pests (notably engraver beetles, Ips sp.), temporarily prevents use of forage by big game and livestock, and is esthetically offensive. On the other hand, thinning greatly increases timber growth and should prevent epidemics of mountain pine beetle (Dendroctonus ponderosae Hopk.). Protection by slash may permit forage to become established or recover from overuse. In any case, forage production increases severalfold, and habitat for wildlife is improved significantly. The thinned forest, after the slash deteriorates, is generally easier to protect and esthetically more pleasing than the unthinned.

Citation

Fahnestock, George R. 1968. Fire hazard from precommercial thinning of ponderosa pine. Res. Pap. PNW-RP-057. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station: 1-21