基于结构方程模型的林分生长与影响因子耦合关系分析

Coupling relationship between stand growth and impacting factors based on structural equation model

为探讨林分生长与影响因素的关系,以阿什河流域天然次生杂木林为例,构建了立地条件--林分结构--树木多样性--林分生长的结构方程模型。结果表明:对三大硬阔(水曲柳、黄波萝和胡桃楸)蓄积量影响最大的因素是立地条件,总影响系数为0.541,直接路径系数为0.597;其次为林分结构,总影响系数为0.402,直接路径系数为0.451;树木多样性对三大硬阔蓄积量存在负影响,直接路径系数为-0.190,无间接影响。对全林分蓄积量影响最大的因素是林分结构,总影响系数为0.776,直接路径系数是0.720;其次为立地条件,总影响系数为0.394,直接路径系数为0.153;树木多样性、三大硬阔蓄积量对全林分蓄积量的总影响系数和间接影响系数分别为0.111、0.060和-0.011、0。立地条件和林分结构对三大硬阔蓄积量有正影响,但其对树木多样性的正影响,可间接负影响到三大硬阔蓄积量。立地条件对全林分生长有正影响,这种影响更多地是通过改善林分结构与树木多样性而间接形成的。林分结构对全林分生长有正影响,树木多样性对三大硬阔蓄积量有负影响,这种负影响对全林分生长的间接作用较小。

In order to find out the relationship between stand growth and impacting factors, the structural equation model of the site condition-stand structure-tree diversity-stand growth was built taking secondary multiple species forest beside Ashi River , Heilongjiang of northeastern China as example. The results showed that among three factors of site condition, stand structure and tree diversity, site condition was the most important factor affecting three hardwood （Fraxinus mandshurica, Phellodendron amurense and Juglans mandshurica） volume, total path coefficient was 0. 541 and direct path coefficient was 0. 597. Structure was the second important factor, total path coefficient was 0. 402 and direct path coefficient was 0. 451. Tree diversity had negative impact on three hardwood volume, direct path coefficient was -0. 190. Among three factors of site condition, stand structure and tree diversity, stand structure was the most important factor affecting stand volume, total path coefficient was 0. 776 and direct path coefficient was 0. 720. Site condition was the second important factor, total path coefficient was 0. 394 and direct path coefficient was 0. 153. Total path coefficients and indirect path coefficients of tree diversity and three hardwood volume to stand volume was 0.111, 0. 060 and - 0.011, 0, respectively. Site condition and stand structure had a positive impact on three hardwood volume, but their positive impact on tree diversity could produce a negative impact on three hardwood volume. Site condition had a positive impact on stand growth, most parts of which was formed indirectly by improving forest structure and tree diversity. Stand structure had a positive impact on stand growth. Tree diversity had a negative impact on three hardwood volume, which had a small indirect impact on stand growth.