摘要
【目的】天然林生长模型一直是国内外林业研究的难点,单木生长模型是林木生长与收获模型的重要组成部分,林分平均木生长过程模拟是单木生长模型乃至林分生长模型的研究基础,密度和立地是影响其生长的重要因素。因此,探讨与构建反应密度和立地差异的栎类天然林胸径生长模型,能客观地反应其生长规律,为林分预估和提高林分质量提供理论支持。【方法】以湖南栎类天然林样地数据为基础,以林分平均木胸径为研究对象,基于树木理论生长方程,利用数量化方法Ⅰ和非线性混合效应回归建模方法,构建含林分密度和立地效应的栎类林分平均木胸径生长模型。【结果】1)利用评价指标(确定系数R^(2)、平均绝对误差MAE及均方根误差RMSE),从4个基础模型中选定Logistic为林分胸径生长的最优基础模型,确定系数R^(2)为0.33897;2)采用数量化方法Ⅰ筛选出海拔、坡度、坡向和株数密度是对林分胸径生长影响显著的因子;3)将海拔、坡度、坡向分级并组成基本立地类型组合,将株数密度和立地类型组合作为混合效应加入到基础模型中构成非线性混合效应模型,模型确定系数由0.33897提升到了0.93016。【结论】胸径的生长既受林分密度的影响,又与立地条件有关,不同的株数密度和立地条件对林分平均木胸径生长的影响很大。林分的密度与胸径呈现负相关,密度越小,林分平均木胸径越大;林分的立地条件越好,林分平均木的胸径越大。考虑株数密度和立地类型效应的生长模型可以有效解决栎类天然林林分密度和立地类型差异对胸径预估的影响。
【Objective】Natural forest growth models have always been a difficult point in forestry research at home and abroad.Single tree growth model is an important part of forest tree growth and harvest model.The simulation of stand average tree growth process is the research basis of single tree growth model and even stand growth model.Density and site are important factors affecting its growth.Therefore,exploring and constructing a DBH growth model of Quercus natural forests that reflect density and site differences can objectively reflect its growth rules and provide theoretical support for forest stand estimation and improvement of stand quality.【Method】Based on the sample plot data of natural Quercus forests in Hunan,the average diameter of wood stands at breast height as the research object,based on the theoretical growth equation of trees,using quantitative method I,using nonlinear mixed effect regression modeling method,constructing the DBH growth model of Quercus forest with stand density and site effect.【Result】1)Using evaluation indicators(coefficient of determination R^(2),average absolute error MAE,and root mean square error RMSE),Logistic is selected from the four basic models as the optimal basic model for the DBH growth of the stand,and the determination coefficient R^(2) is 0.33897;2)Use quantitative method I to screen out that altitude,slope,aspect and plant number density are factors that have significant effects on the DBH growth of the stands;3)Classify altitude,slope and aspect to form a combination of basic site types,add the combination of plant number density and site type to the basic model as a mixed effect Form a non-linear mixed effects model,the model determination coefficient increased from 0.33897 to 0.93016.【Conclusion】The growth of diameter at breast height is not only affected by forest density,but also related to site conditions.Different plant number densities and site conditions have a great influence on the DBH growth of stands.The density of forest stands is negatively correlated with diameter at breast height.The lower the density,the larger the average DBH of the stand;the better the site conditions of the stand,the larger the DBH of the average stand.A growth model that takes into account the plant number density and site type effects can effectively solve the impact of Quercus natural forest stand density and site type differences on the estimation of DBH.
作者
何静
朱光玉
张学余
王忠诚
刘洪娜
屠维亚
HE Jing;ZHU Guangyu;ZHANG Xueyu;WANG Zhongcheng;LIU Hongna;TU Weiya(College of Forestry,Central South University of Forestry&Technology,Changsha 410004,Hunan,China;Qingyanghu State-owned Forest Farm,Ningxiang 410627,Hunan,China;The Forestry Department of Jindong Management District,Yongzhou 426191,Hunan,China)
出处
《中南林业科技大学学报》
CAS
CSCD
北大核心
2021年第10期75-82,共8页
Journal of Central South University of Forestry & Technology
基金
国家自然科学基金项目(31570631)
湖南省教育厅重点项目(16A224)
湖南省自然科学基金面上项目(2017JJ2405)
湖南省教育厅一般项目(18C0277)
中南林业科技大学研究生科技创新基金项目(CX20192070)。
