Optimal uneven-aged stocking guides: an application to spruce-fir stands in New England. (Themed issue on uneven-aged silviculture.)

摘要

Management guides for uneven-aged forest stands periodically need to be revisited and updated based on new information and methods. The current silvicultural guide for uneven-aged spruce-fir management in Maine and the northeast (Frank, R.M. and Bjorkbom, J.C. 1973 A silvicultural guide for spruce-fir in the northeast. General Technical Report NE-6, Forest Service. U.S. Department of Agriculture) presents two options for each of three different cutting cycles, and all guides are based on a negative exponential distribution for the number of trees by diameter class. While this guide claims to be optimal, it will be demonstrated that it is not necessarily optimal in any commonly accepted sense and is overly restrictive in its adherence to the negative exponential model of stand structure. We review a methodology that allows the objective determination of optimal stocking guides for uneven-aged stands that can be tailored to the individual stand and provides consideration for a number of alternative objectives and cutting cycles. These guides do not necessarily conform to the strict negative exponential distribution. They also suggest residual basal areas somewhat lower than those recommended by the current spruce-fir silvicultural guide for the northeastern USA.