Extended rotations and culmination age of coast Douglas-fir: old studies speak to current issues.

Abstract

Trends of mean annual increment and periodic annual increment were examined in 17 long-term thinning studies in coast Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) in western Washington, western Oregon, and British Columbia. Maximum ages included ranged from about 90 years on high sites to 117 years on a low site. None of the stands had clearly reached culmination of mean annual increment, although some appeared close; periodic annual increments declined only slowly. Extended rotations combined with increased thinning harvests are promising components of any strategy to reduce conflicts between timber production and other forest values. These comparisons indicate that rotations can be considerably extended without reducing long-term timber production. A major problem in such a strategy is design of thinning regimes that can maintain some reasonable level of timber flow during any transition period.

Citation

Curtis, Robert O. 1995. Extended rotations and culmination age of coast Douglas-fir: old studies speak to current issues. Res. Pap. PNW-RP-485. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 49 p