少花蒺藜草入侵与干旱对羊草群落生产力的影响机制

白皓然, 侯盟, 刘艳杰

Mechanisms of the invasion of Cenchrus spinifex and drought effects on productivity of Leymus chinensis community

BAI Hao-Ran, HOU Meng, LIU Yan-Jie

图6 入侵与水分及其相互作用对细菌绝对丰度、真菌有效物种数、丛枝菌根真菌优势菌球囊霉科菌、土壤节肢动物群落丰富度、土壤有效氮含量和群落生产力影响的结构方程模型。在图中, 箭头表示路径, 在正方形(■)处连接到路径的线表示交互作用; 沿着路径的数字是标准化系数。对于模型, Satorra-Bentler校正χ² = 13.535, p = 0.561, 说明模型中不存在缺失路径。比较拟合指数(CFI)在对假设模型和独立模型比较时取得, 其值在0-1之间, 愈接近0表示拟合愈差, 愈接近1表示拟合愈好。近似误差均方根(RMSEA)是评价模型不拟合的指数, 如果接近0表示拟合良好, 相反, 离0愈远表示拟合愈差。标准化均方根残差值(SRMR), SRMR愈小, 表示模型拟合度愈高。SRMR = 0表示完美拟合, SRMR < 0.05一般为良好的拟合标准, SRMR < 0.08一般为可接受的拟合标准。

Fig. 6 Structural equation modeling of the invasion and water and their interactions on absolute bacterial abundance, effective number of species (ENS) of fungi, Glomeraceae, soil arthropod richness, soil available nitrogen content (AN) and native community productivity. In the diagram, arrows indicate paths, lines connect to the paths at the squares (■) indicate interactions; numbers along the paths are standardized coefficients. For the model, Satorra-Bentler corrected χ² = 13.535, p = 0.561, indicating there were no missing paths in the model. Comparative fit index (CFI) is obtained when comparing the hypothetical model and the independent model, and its value is between 0 and 1, closer to 0 means worse fit, and closer to 1 means better fit. Root-mean-square error of approximation (RMSEA) is the index that evaluates the model to not fit, if it is close to 0, the fit is good, conversely, the further from 0, the worse the fit. Standardized root mean square residual (SRMR), SRMR = 0 means a perfect fit, SRMR < 0.05 indicates a good fit, SRMR < 0.08 represents an acceptable fit.