摘要
以东北林业大学帽儿山实验林场46块样地共2009株天然椴树为研究对象,从已有的10个冠幅预测模型中选出较好的冠幅直径模型作为基础模型,且考虑样地、林木因子、立地因子、竞争和其它因素等对冠幅大小的影响,构建基于样地水平的非线性混合效应模型。结果表明:逻辑斯蒂形式的冠幅直径模型拟合效果较好;第一活枝高(HCB)、优势木平均高(Ht)和椴树的树种组成系数(P)是影响冠幅的主要因子,且冠幅均随着变量HCB、Ht和P的增加而减少;混合效应模型的调整决定系数(R2adj)和均方根误差(RMSE)分别为0.5250和0.4247m,平均误差、平均绝对误差和相对平均绝对误差分别为-0.0047m、0.3557m和17.9365%。与基础模型相比,混合效应模型的R2adj提高了17.6%,RMSE降低了7.4%。此外,基于数据结构的特点,构建的椴树单木冠幅模型,只适用于对阔叶混交林中小径阶椴树的冠幅进行预测,而不适用于对大径阶椴树的冠幅进行预测。
An individual crown diameter model was developed based on a data set consisting of 2009 natural Tilia tuan Szyszyl. trees from 46 plots located in Maoershan Experimental Forestry Farm of Northeast Forestry University. Because of the problem of high correlation among observations taken from the different sample plot, the random effects of sample plots to crown diameter were considered, namely, developing the nonlinear mixed effect crown width model. Base model used in developing mixed model was selected from 10 models reported in the literatures, and the effects of tree factors, site factors, competition and other factors to crown diameter were considered. The crown width-diameter model of logistic form had a better fit effect and was selected as base model. The height to live crown base Tilia tuan Szyszyl ( H CB ), dominant height of plot ( H t ) and the basal area proportion of T. tuan ( P ) were significant factors in crown width model, and the crown width all decreased with the increase of ( H CB ), H t and P;The adjusted coefficient of determination ( R 2 adj ) and the root mean square error ( R MSE ) of the mixed effect model were 0.525 0 and 0.424 7 m, respectively, and the mean error, mean absolute error and relative average absolute error of the mixed effect model were -0.004 7 m, 0.355 7 m and 17.936 5%, respectively. Compared to the basic model, the R 2 adj of the mixed effect model increased 17.6%, while RMSE decreased 7.4%. In addition, based on the characteristics of the data structure, the developing individual tree crown width nonlinear mixed effect model for T. tuan were only applied to the crown width of the small diameter classes within the broad leaved mixed forest, and not to the crown width of the large diameter classes Tilia .
作者
吕乐
董利虎
李凤日
Lü Le;Dong Lihu;Li Fengri(Northeast Forestry University, Harbin 150040, P. R. China)
出处
《东北林业大学学报》
CAS
CSCD
北大核心
2019年第7期37-42,共6页
Journal of Northeast Forestry University
基金
国家林业局林业科学技术推广项目【2016】36号
关键词
椴树
单木冠幅模型
阔叶混交林
非线性混合效应模型
Tilia tuan Szyszyl.
Individual tree crown width model
Broad leaved mixed forest
Nonlinear mixed effect model
