Affiliation:
1. College of Forestry, Hebei Agricultural University, Baoding 071001, China
2. College of Economics and Management, Hebei Agricultural University, Baoding 071001, China
Abstract
Competition among free branches in the tree canopy is an important factor influencing branch length growth. Therefore, there is a need to quantify this competition and to understand the impact of the regression technique on the predictive accuracy of the growth of free branch length (GFBL) model in a Larix principis-rupprechtii plantation. This study focused on an L. principis-rupprechtii plantation in Saihanba Mechanized Forest Farm. Five competition indices based on 2176-branch data points from 76 trees were used to quantify the branch competition, and three regression techniques (nonlinear least squares (NLS), nonlinear mixed-effects model (NLME), and nonlinear quantile regression (NQR)) were used to construct the GFBL model including the branch competition index. The results showed that the Chapman–Richards growth function, including the diameter at breast height (DBH) and depth of branch into crown (DINC), was the optimal equation for describing the GFBL in the studied L. principis-rupprechtii plantation. The branch competition index (CI) was found to be optimal for quantifying the branch competition when used with the maximum value parameter (a0) of the Chapman–Richards growth function. The three parameter estimation methods were compared, and the NLME, which included the CI, was found to have the highest predictive accuracy. The results of this study can act as a reference for improving the management, assessing the management effectiveness, and enhancing the quality of L. principis-rupprechtii plantations.
Funder
Hebei Province Key R & D Program of China
National Natural Science Foundation of China
National Key Research and Development Program of China
Reference50 articles.
1. Effect of wide spacing on increment and branch properties of young Norway spruce;Hein;Eur. J. For. Res.,2006
2. Crown development in a pioneer tree, Rhus trichocarpa, in relation to the structure and growth of individual branches;Osada;New Phytol.,2006
3. Predicting the effects of silvicultural regime on branch size and crown wood core in Douglas-fir;Maguire;For. Sci.,1991
4. Branch models for white spruce (Picea glauca (Moench) Voss) in naturally regenerated stands;Sattler;For. Ecol. Manag.,2014
5. Factors influencing the amount and distribution of leaf area of pine stands;Vose;Ecol. Bull.,1994