图6. 底座入土深度和底座面积对土壤呼吸速率影响的结构方程模型分析。模型模拟的结果为: χ² = 0.89, p = 0.874 > 0.085, df = 5, RMSEA = 0.000 < 0.05, AGFI = 0.900 > 0.90, GFI = 0.975 > 0.90 (模型模拟的结果更合理)。其中, 黑色实线箭头表示显著的正相关路径(p < 0.05), 灰色实线箭头表示显著的负相关路径, 虚线箭头表示不显著的路径。箭头上的数字表示标准化路径系数。r²表示模型对该变量的解释度。RMSEA, 近似误差均方根; AGFI, 调整拟合优度指数; GFI, 拟合优度指数。**, p < 0.01; ***, p < 0.001。

Fig. 6. Structural equation modeling analysis for the effects of collar depth (D) and size (S) on soil respiration rate, via pathways of biotic and abiotic factors during the study period. Square boxes indicate variables included in the model. Results of model fitting: χ² = 0.89, p = 0.874 > 0.085, df = 5, RMSEA = 0.000 < 0.05, AGFI = 0.900 > 0.90, GFI = 0.975 > 0.90 (which indicates a good fit of the model to the data). Black and gray solid arrows indicate significantly positive and negative effects, respectively and dashed arrows indicate insignificant effects (p > 0.05). Values associated with the arrows represent standardized path coefficients. R² values associated with response variables indicate the proportion of variation explained by relationships with all other variables. RMSEA, root-mean-square error of approximation; AGFI, adjusted goodness-of-fit index; GFI, goodness-of-fit index. post-ANPP, post aboveground net primary productivity; SR, soil respiration; ST, soil temperature; SWC, soil water content. **, p < 0.01; ***, p < 0.001.