Crown-width prediction models for several tree species including Larix olgensis in northeastern China

The mean crown-width of stand-grown trees was modeled as a function of stem diameter at breast height, tree height, crown length, crown ratio, competition index and stand density for several tree species in 20 mixed stands of Larix olgensis, Abies nephrolepis and Picea jazoensis in northeastern China. Multivariate stepwise regression was performed with the data of 3 099 crown-width observations for nine tree species including L. olgensis, P. jazoensis, A. nephrolepis, Pinus koraiensis, Betula costata, B. platyphylla, Acer mono, Tilla amurensis and Fraxinus mandshurica.Results showed that tree diameter at breast height and stand density were significant variables in crown-width prediction models for all tree species. The adjusted R² value was between 0.34 and 0.75. Absolute and relative bias values were between -0.000 114 and 0.054 m, -0.054 43% and 3.440%, respectively. RMSE and relative RMSE values were from 0.360 to 0.510 m, and 27.4% to 37.4%, respectively.