PJB-2018-805
Improving Individual Crown Biomass Estimation by Incorporating Competition Factors Using Mixed Effect Models for Pinus kesiya var. langbianensis
Meiling Xu
Abstract
To improve crown biomass estimation, the crown biomass of 128 sampling trees had been investigated at three typical sites of Simao Pine (Pinus kesiya var. langbianensis) natural forest in Pu’er city of Yunnan province, China. Based on selection of the basic model forms for the crown biomass, considering random effects of the site index effect, and incorporating competition factors in the mixed effect models, branches and needles biomass models had been constructed using the technology of nonlinear mixed effect model. The results showed that: (1) Mixed effects models are better than the ordinary models significantly. The mixed effects models including the fixed effect of competition factors has better fitting performance than ordinary mixed model for branches biomass, but for the needles biomass the mixed effects models without fixed effect of competition factors have the best fitting performance. (2) Mixed effect models incorporating competition factors have better prediction ability because of the highest prediction precision for both branches and needles biomass, and the values are 70.27% and 66.57% respectively. Mixed-effects models considering site effect and competition factors may provide a flexible and powerful tool for individual crown biomass estimation.
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