中南林业科技大学学报2025，Vol.45Issue(9)：71-81,105,12.DOI:10.14067/j.cnki.1673-923x.2025.09.008
基于竞争指数的马尾松冠幅模型构建
Construction of Pinus massoniana crown width model based on competition index
摘要
Abstract
[Objective]To analyze the correlation between forest competition and crown width of Pinus massoniana,we constructed a generalized crown width model,generalized additive model and nonlinear mixed effect model with competition index to compare and analyze the fitting effects of different models,and select the optimal crown width prediction model of Pinus massoniana.It provides a theoretical basis for more fully expressing the crown characteristics of Pinus massoniana and scientific management and management of Pinus massoniana plantation.[Method]In this study,2 259 Pinus massoniana in Nanmudu Town,Kaiyang County,Guizhou Province were selected as the research object.The edge effect was eliminated by eight-neighborhood translational method,and the competing units were determined by Voronoi diagram.The correlation between competition and crown width of Pinus massoniana was analyzed by Pearson correlation analysis,combined with Hegyi competition index(CI1),cross Angle competition index(CI2)and comprehensive competition index(CI3).The basic crown model was extended,and a generalized model,a generalized additive model and a nonlinear mixed effect model with the above three competition indices were constructed.The fitting accuracy of the models was compared,and the influence of the competition on the model was analyzed.At the same time,the prediction ability of the model was tested by 10-fold cross-validation.[Result]1)The three competition indexes are negatively correlated with the crown width of Pinus massoniana.(P＜0.001).There is a very significant positive correlation between the three competition indexes(P＜0.001),and the correlation between(CI1)and(CI3)was stronger;2)In the fitting of basic models,the logistic model has the highest fitting accuracy(R2=0.610 5,RMSE=0.742 9 m,MAE=0.585 1 m,AIC=5 075.895),and is selected as the optimal basic model;3)No matter before or after adding the competition index,the fitting accuracy of the model is nonlinear mixed effect model,generalized additive model and generalized model in order from high to low;4)The addition of competition index can improve the accuracy of the three models.In both the generalized model and the generalized additive model,the model effect is the best when CI3 is added,and the model effect is the best when CI1 is added to the mixed effect model and is better than other models.[Conclusion]There is a significant negative correlation between the three competition indexes and the crown width of Pinus massoniana,indicating that competition has a significant inhibitory effect on the growth of crown width.The addition of covariates and random effects can greatly improve the prediction accuracy of the canopy width model.Adding competition index can improve the prediction accuracy of the model,but different competition index has different performance ability in different models.Compared with the basic model,the generalized model and the generalized additive model,the nonlinear mixed effect model constructed in this study has higher fitting accuracy,and is the best model for predicting the crown width of Pinus massoniana.关键词
马尾松/冠幅模型/竞争指数/非线性混合效应模型/广义可加模型Key words
Pinus massoniana/crown width model/competition index/nonlinear mixed effect model/generalized additive model分类
农业科技引用本文复制引用
谭茜,谭伟,田昕,梅本清,樊隆高..基于竞争指数的马尾松冠幅模型构建[J].中南林业科技大学学报,2025,45(9):71-81,105,12.基金项目
国家重点研发计划项目(2023YFD2201705). （2023YFD2201705）
