Abstract

Branch growth is an important aspect of the tree growth process. Studying the branch growth pattern is important for understanding the growth of trees and optimizing forest management decisions. A total of 48 planted Korean pine sample trees from northeast China were selected, and a total of 327 sample branches were measured for branch diameter growth model development and 323 sample branches for branch length. Based on the aforementioned research objectives and the obtained data, the impact of individual tree variables, branch variables, and forest stand competition variables on branch growth were initially investigated in this study. Finally, we constructed nonlinear mixed-effects models at the individual tree level. The results show that the Mitscherlich growth equation had the best fitting accuracy and was selected as the base model for developing the Korean pine branch growth model. Forest stand competition of the ratio of the basal area of the subject tree to the mean basal area of the stand (CI₂) and branch variables of the branch length and branch diameter had the most significant contributions and were selected and introduced into the branch growth models. The branch growth became larger with increasing CI₂, branch length and branch diameter, but the effects of the branch height and diameter at the breast height on branch growth should be considered in combination with their parameters and other variables together. In addition, the introduction of random effects effectively improves the fitting accuracy of the branch growth model. Overall, the Korean pine branch growth models developed in this study have good fitting performance and have important theoretical and practical value.

中文翻译：

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东北人工红松非线性混合效应枝条生长模型研究

摘要

枝条生长是树木生长过程的一个重要方面。研究树枝生长模式对于了解树木的生长和优化森林管理决策具有重要意义。共选取了48棵来自东北地区的种植红松样树，共测量了327个样枝进行枝径生长模型开发，测量了323个样枝的枝长。基于上述研究目标和获得的数据，本研究初步探讨了单树变量、枝条变量和林分竞争变量对枝条生长的影响。最后，我们在单个树级别构建了非线性混合效应模型。结果表明，Mitscherlich生长方程拟合精度最好，被选为红松枝条生长模型的基础模型。林分竞争中主题树的断面积与林分平均断面积之比（CI ₂）以及枝条长度和枝条直径的枝条变量贡献最显着，被选择并引入枝条生长楷模。_{分枝生长随着CI 2} 、分枝长度和分枝直径的增加而增大，但分枝高度和胸高直径对分枝生长的影响应结合它们的参数和其他变量一起考虑。此外，随机效应的引入有效提高了分支生长模型的拟合精度。总体而言，本研究建立的红松枝条生长模型具有良好的拟合性能，具有重要的理论和实用价值。