A local basal area adjustment for crown width prediction

Abstract

Nonlinear crown width regression equations were developed for 24 species common to the upper Lake States of Michigan, Minnesota, and Wisconsin. Of the species surveyed, 15 produced statistically significant (P < 0.05) local basal area effect coefficients showing a reduction in crown width with increasing stand density. No relation bet\veen shade tolerance and crown width was apparent, indicating the speciesdependence of this parameter. Using adjusted R2 as a guide, nonlinear crown width models adapted for local basal area (NLCWadj) improved prediction for 20 of24 species over a model lacking this component (NLCW). The ecolosical significance of the improvement shown for some species mav be minor, but for others the difference was substantial (often 8%).