利用全国森林资源连续清查数据,选取秦巴山区天然栎类林作为研究对象,基于竞争指数确定优势木及其竞争等级;根据优势木和立地主导因子确定立地质量等级;将竞争等级和立地质量等级作为哑变量逐步参与胸径、树高生长过程拟合,确定最优生长模型。研究发现:栎类天然林的立地主导因子为海拔、坡向和土壤厚度;胸径、树高生长模型的最优基础模型均为Gompertz模型;胸径生长模型以竞争等级哑变量位于参数a,c时拟合结果最好,其中R²值和P_a值分别为0.834和98.17,较基础模型分别提高13.16%,0.59%;树高生长模型以立地质量等级哑变量位于参数a,b时拟合结果最好,其中R²值和P_a值分别为0.717和98.26,较基础模型分别提高16.59%和0.65%;当胸径和树高模型引入第二类哑变量时,模型精度虽有提升但效果不明显。分析秦巴山区不同生长条件下天然栎类林的胸径和树高生长规律,建立林分生长模型,以期为天然栎类次生林修复与林分质量提升提供重要参考。

Based on the national forest resources inventory data,this study takes the natural oak forest in Qinba mountain area as the research object.The dominant trees and their competitive grades were determined based on the competition index and the site quality grade was determined according to the dominant trees and site dominant factors.The competition grade and site quality grade were used as dummy variables in the fitting of the growth process of the DBH and tree height to obtain the optimal growth model.The results showed that the dominant site factors of oak natural forest were altitude,aspect and soil thickness;Gompertz model was the optimal basic model for the DBH and tree height growth model;the best fitting results were obtained when the dummy variable of competition grade was in parameters a and c,in which R ² value and P_a value were 0.834 and 98.17,respectively,13.16% and 0.59% higher than those of the basic model. The study found that the height growth model used Gompertz model when the dummy variables of site quality grade were in parameters a and b,the fitting results were the best.R ² value and P_a value were 0.717 and 98.26 respectively,which were 16.59% and 0.65% higher than those of the basic model.When the second kind of dummy variable is introduced into the DBH and tree height model,the accuracy of the model is improved,but the effect is not obvious.Based on the analysis of the DBH and tree height growth rules of natural oak forest under different growth conditions in Qinba mountain area,the stand growth model was established,which can provide important reference for the restoration of natural oak secondary forest and the improvement of stand quality.