Density Management Diagram for Northeastern Red Spruce and Balsam Fir Forests

Abstract

Abstract A stand-density management diagram is presented for use in northeastern red spruce and balsam fir forests. The diagram was derived from an extensive archived data set collected during the 1970s from fully stocked stands throughout northern Maine and a more recent study of precommercially thinned stands. The negative exponential relationship between mean stemwood volume per tree and stand density, commonly known as the "self-thinning rule, "was formulated to define a biological maximum stand density. The maximum size-density equation can be used to calculate the relative density of any stand and is accurate for thinned and unthinned natural stands as well as plantations. Equations for estimating quadratic mean diameter and stand top height are also derived for unthinned natural stands only. Data used to fit the self-thinning line are substantially above the A-lines on the familiar northeastern stocking guides, suggesting that these guides underestimate maximum density and thus overpredict self-thinning. Examples illustrate how to use the diagram to predict stand development under commercial and precommercial thinning scenarios, as well as natural stand development without thinning. Relevant site index and volume equations are included in an appendix. North. J. Appl. For. 16(1):48-56.