草地土壤有机质不同组分氮库对长期氮添加的响应

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武运涛¹^,², 杨森¹^,², 王欣¹, 黄俊胜¹, 王斌¹^,², 刘卫星¹, 刘玲莉¹^,²^,^*(

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Responses of soil nitrogen in different soil organic matter fractions to long-term nitrogen addition in a semi-arid grassland

WU Yun-Tao¹^,², YANG Sen¹^,², WANG Xin¹, HUANG Jun-Sheng¹, WANG Bin¹^,², LIU Wei-Xing¹, LIU Ling-Li¹^,²^,^*(

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图6. 氮添加对颗粒态有机质(POM)(A)和矿质结合态有机质(MAOM)(B)的氮含量影响途径的结构方程模型(SEM)分析结果。模型拟合的结果: POM_N, χ² = 0.480, p = 0.787, 相对拟合指数(CFI) = 1.000, 近似误差平方根(RMSEA) < 0.001; MAOM_N, X² = 2.856, p = 0.414, CFI = 1.000, RMSER < 0.001。实线箭头代表显著的效应(p < 0.05), 虚线箭头代表没有显著的效应(p > 0.05), 箭头附近的数字代表标准化的路径系数。

Fig. 6. A schematic representation of the structural equation modeling (SEM) analysis used to identify the controls of soil nitrogen (N) content in particulate organic matter (POM)(A) and mineral associated organic matter (MAOM)(B) under N addition. Results of the model fitting were: POM_N, X² = 0.480, p = 0.787, comparative fit index (CFI) = 1.000, root-mean-square (RMSEA) < 0.001; MAOM_N, X² = 2.856, p = 0.414, CFI = 1.000, RMSEA < 0.001. Solid and dashed arrows represent significant effect (p < 0.05) and insignificant effect (p > 0.05), respectively. Number adjacent to the arrows refer to the standardized path coefficients. AGB, aboveground biomass; DIN, dissolved inorganic nitrogen; MBC, microbial biomass carbon.