林业科学2016，Vol.52Issue(1)：30-36,7.DOI:10.11707/j.1001-7488.20160104
基于非线性混合模型的针阔混交林树高与胸径关系
Height-Diameter Relationship for Conifer Mixed Forest Based on Nonlinear Mixed-Effects Model
摘要
Abstract
[Objective]This paper established the nonlinear mixed effects model for height-diameter relationship in multi-storied and multi-species mixed forests. The purpose of this study was to provide some references for the further study on growth rule in mixed forests. [Method]A total of 87 temporary plots were used in Larix principis-rupprechtii and Betula platyphylla mixed forest of Saihanba National Forest Park,Hebei Province,China. Plot size was 20 m × 30 m. A total of 4 953 individuals of Larix principis-rupprechtii and 3 608 individuals of Betula platyphylla were investigated. 13 typical models were selected to fit height-diameter relationship. The best-fit model was chose as the basis for building mixed-effects models. Both fixed-and random-effects parameters expressed in terms of high species strengths and stand basal area were considered to establish height-diameter relationships. Furthermore,dummy variables were added to the mixed-effects models in order to solve intra-plot variability resulting from species difference. The goodness-of-fit criteria used were the coefficient of determination (R2),the absolute error of estimate (Bias) and the root mean square error(RMSE). [Result]1) Among the 13 pieces of height-diameter candidate models,model 13 (M13) provided the most accurate prediction of height with the highest R2(0. 915 7),the lowest Bias (1. 200 6) and RMSE (0. 129 1). 2) For Larix principis-rupprechtii and Betula platyphylla,mixed effects models were established based on M13,respectively. Both models had the best fits with the fit statistics values (R2 =0. 926 4; AIC=319. 7; Bias=0. 084 1; RMSE=1. 070 8) for Larix principis-rupprechtii and values ( R2 = 0. 918 7; AIC = 297. 6; Bias = 0. 070 5; RMSE = 1. 102 2 ) for Betula platyphylla. 3) To further evaluate mixed-effects models for two species,trees from the validation data were divided into different DBH classes with every 2 cm interval. The average values of height prediction bias ( observed-predicted) were small for both species. The above results indicated that mixed-effects models including species dummy variable provided in a better fit to the data and improved prediction accuracy. [Conclusion]The mixed-effects models with dummy variables solved the negative effects of species differences between plots and within plot on height-diameter relationships in mixed forests. It was proved able to provide better model fitting,more applicability and more precise estimations than the basic generalized model.关键词
非线性混合模型/华北落叶松/白桦/树高-胸径/混交林Key words
nonlinear mixed model/Larix principis-rupprechtii/Betula platyphylla/height-diameter/mixed forest分类
农业科技引用本文复制引用
王冬至,张冬燕,张志东,黄选瑞..基于非线性混合模型的针阔混交林树高与胸径关系[J].林业科学,2016,52(1):30-36,7.基金项目
林业公益性行业科研专项( 20150430304 ) （ 20150430304 ）
国家自然科学基金项目 ( 31370636 ) （ 31370636 ）
科技部十二五科技支撑计划(2012BAD22B0304). （2012BAD22B0304）
