结构方程模型在兴安落叶松林生长中的应用

【目的】通过结构方程模型，确定气候、土壤和海拔对兴安落叶松林生长指标的影响以及路径关系。【方法】选取年平均气温、年平均降水量、太阳辐射、土壤全氮含量、土壤有机碳密度和海拔作为影响因素，探究兴安落叶松地上生物量、地下生物量、树高与这些影响因素的关系，并利用AMOS 21.0软件构建衡量兴安落叶松生长的3个指标与气候、土壤和海拔的结构方程模型。【结果】兴安落叶松的地上生物量、地下生物量随着海拔、年平均降水量的增大呈现先增大后减少的趋势，树高随着海拔的增加而增加。地上和地下生物量随着土壤有机碳密度的增加而增加。海拔对兴安落叶松生长的总效应系数为0.200且是正向效应，海拔对兴安落叶松生长的直接效应(0.224)大于间接效应(-0.024);气候因子对兴安落叶松林生长的总影响系数为-0.771且是负向效应；土壤因子对兴安落叶松生长的总影响系数为-0.216,其对兴安落叶松林生长起到一定的抑制作用。【结论】根据结构方程模型的路径系数，气候因子的总影响系数绝对值最大，其次是土壤和海拔，兴安落叶松林静态生长主要受到气候因子的制约。

Application of structural equation model in growth of Larix gmelinii stand

【Objective】 Structural equation modelling (SEM) was used to determine the effects of climate, soil, and altitude on growth indicators and pathway relationships in Xing’an larch (Larix gmelinii) forests. 【Method】 The annual mean temperature, annual mean precipitation, solar radiation, soil total nitrogen content, soil organic carbon density, and altitude were selected as influencing factors to explore the relationships between aboveground biomass, underground biomass, and tree height and these underlying factors. A structural equation model of climate, soil, and altitude was constructed using AMOS 21.0 software to measure the growth of Larix gmelinii stand. 【Result】 The aboveground and underground biomass of Larix gmelinii first increased and then decreased with an increase in altitude and annual mean precipitation, and the tree height increased with increasing altitude. The aboveground and underground biomass increased with an increase in soil organic carbon density. The total effect coefficient of altitude on the growth of Larix gmelinii was positive (0.200), and the direct effect (0.224) of altitude on the growth of Larix gmelinii was greater than the indirect effect (-0.024). The total effect coefficient of the climatic factors on the growth of Larix gmelinii was negative, at -0.771. The total influence coefficient of soil factors on the growth of Larix gmelinii was -0.216, which means these factors can slightly inhibit the growth of Larix gmelinii. 【Conclusion】 According to the path coefficient of the structural equation model, the absolute value of the total influence coefficient of climate factors was the largest, followed by that of soil and altitude. The static growth of Larix gmelinii forest is mainly restricted by climatic factors, which has guiding significance for predicting and evaluating changes in forest growth at high latitudes under the condition of global climate change.