Crown-diameter prediction models for 87 species of stand-grown trees in the eastern United States

The mean crown diameters of stand-grown trees were modeled as a function of stem diameter, live-crown ratio, stand basal area, latitude, longitude, elevation, and Hopkins bioclimatic index for 87 tree species in the eastern United States. Stem diameter was statistically significant in all models, and a quadratic term for stem diameter was required for some species. Crown ratio and/or Hopkins index also improved the models for many species. Coefficients of variation from the regression solutions ranged from 18 to 35%, and model r-square values ranged from 0.15 to 0.88. Simpler models, based only on stem diameter and crown ratio, are also presented.