Largest-Crown-Width Prediction Models for 53 Species in the Western United States

The mean crown diameters of stand-grown trees 5.0-in. dbh and larger were modeled as a function of stem diameter, live-crown ratio, stund-level basal area, latitude, longitude, elevation, and Hopkins bioclimatic index for 53 tree species in the western United States. Stem diameter was statistically signi@ant in all models, and a quadratic term for stem diameter was requiredfor some species. Crown ratio and/or Hopkins index also improved the models for most species. A term,for stand-level basal area was not generally needed but did yield some minor improvementfor a,few species. Coeficients of variation from the regression solutions rangedJrom 17 to 33%, and model R2 rangedfrom 0.15 to 0.85. Simpler models, based solely on stem diameter, are also presented. West. J. Appl. For. 19(4):245-251.