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作 者:王冬至[1,2] 弥宏卓 张冬燕[1] 张志东[1,2] 黄选瑞[1,2]
机构地区:[1]河北农业大学,河北保定071000 [2]河北省林木种植资源创新与保护实验室,河北保定071000 [3]内蒙古自治区林业监测规划院,内蒙古呼和浩特010020
出 处:《西北林学院学报》2017年第3期1-6,共6页Journal of Northwest Forestry University
基 金:国家科技支撑计划课题(2015BAD09B01);林业公益性行业科研专项(20150430304);国家自然科学基金(31370636)
摘 要:以河北省塞罕坝国家森林公园华北落叶松—白桦针阔混交林为研究对象,基于87块标准地(20m×30m)的348株解析木数据,建立包含样地间及样地内随机效应的胸径—年龄非线性混合效应模型,并在混合效应模型中加入哑变量来解决样地内不同树种带来的差异。结果表明,华北落叶松单木胸径非线性混合效应模型确定系数(R2)、-2log Likelihood值、信息准则(Alcaikes information criterion,AIC)值、贝叶斯信息(Bayesion informatian criterion,BIC)值分别为0.85、898.1、880.2、855.4;白桦单木胸径非线性混合效应模型确定系数(R2)、-2log Likelihood值、AIC值、BIC值分别为:0.81、500.9、482.6、465.7。白桦和华北落叶松最大年生长量分别为0.44cm和0.41cm,年龄和竞争指数与胸径生长量呈负相关关系,胸径和林分优势高与胸径生长量呈正相关关系,其中林分优势高与华北落叶松—白桦混交林径向生长量相关性较低。包含哑变量的混合效应生长模型解决了混交林中样地间及样地内树种对胸径生长的影响,提高了模型精度及适用性,为该地区针阔混交林经营水平及经营效果的提高提供依据。A total of 87 temporary plots (20 m×30 m) were established in Larix principis-rupprechtii and Betula platyphylla mixed forest of Saihanba National Forest Park,Hebei Province,China.We investigated a total of 348 analytic trees.Nonlinear mixed-effects model of diameter was established including random-effects of plots.We also added dummy variables to the mixed-effects models in order to solve intra-plot variability resulting from species difference.The results indicated that for L.principis-rupprechtii and B.platyphylla,nonlinear mixed-effect models were established respectively.Both models had the best fits with the fit statistics values (R2=0.85;-2 log Likelihood=898.1;AIC=880.2;BIC=855.4) for L.principis-rupprechtii and values (R2=0.81;-2 log Likelihood=500.9;AIC=482.6;BIC=465.7) for B.platyphylla.The maximum annual growth of B.platyphylla and L.principis-rupprechtii were 0.44 cm and 0.41 cm,respectively.The age and competition index had a negative correlation with diameter annual radial growth.The DBH and dominant height of stand had a positive correlation with diameter annual radial growth.Dominant height of stand had a lower correlation with annual radial growth in L.principis-rupprechtii and B.platyphylla mixed forest.The mixed-effect models with dummy variables solved the negative effects of species differences between plots and within plot on diameter relationships in mixed forests.The results would povide better model fitting,more applicability and more precise estimations than the basic generalized model.
关 键 词:非线性混合模型 哑变量 胸径 华北落叶松 白桦 混交林
分 类 号:S758.55[农业科学—森林经理学]
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