Yields of three Douglas-fir (Pseudotsuga menziesii) plantations on former farmland were substantially greater than DFSIM yields for the plantations based on site index estimates from adjacent natural stands. Volume yield per acre of trees 1.6 in. dbh and larger was 40 to 57% greater in the actual plantations than in the simulations. For trees 7.6 in. dbh and larger, volume yield of the actual plantations was 85 to 151% greater than the simulated yields. Mean annual increment of the actual plantations was 56 to 69% greater than the simulated values. In addition, top height was greater in two of the plantations than predicted. Running a second set of simulations with site index estimates based on plantation trees reduced the discrepancy in yields but still resulted in substantial underpredictions. Some possible reasons for enhanced yield of the plantations on former farmland are greater site uniformity, reduced vegetative competition, and increased nutrient availability. West. J. Appl. For. 5(4):00-00, October 1990.
Each regional journal of applied forestry focuses on research, practice, and techniques targeted to foresters and allied professionals in specific regions of the United States and Canada. The Western Journal of Applied Forestry covers the western United States, including Alaska, and western Canada; WJAF will also consider manuscripts reporting research in northern Mexico that has potential application in the southwestern United States.