Modeling Free Branch Growth with the Competition Index for a Larix principis-rupprechtii Plantation

Competition among free branches in the tree canopy is an important factor influencing branch length growth. Therefore, there a need to quantify this competition and understand impact of regression technique on predictive accuracy growth (GFBL) model Larix principis-rupprechtii plantation. This study focused L. plantation Saihanba Mechanized Forest Farm. Five indices based 2176-branch data points from 76 trees were used competition, three techniques (nonlinear least squares (NLS), nonlinear mixed-effects (NLME), quantile (NQR)) construct GFBL including index. The results showed that Chapman–Richards function, diameter at breast height (DBH) depth into crown (DINC), was optimal equation for describing studied index (CI) found be quantifying when with maximum value parameter (a0) function. estimation methods compared, NLME, which included CI, have highest accuracy. can act as reference improving management, assessing management effectiveness, enhancing quality plantations.