Fig. 4

Path model depicting the regulatory pathway of the controls of soil extracellular enzymes activities of soil physical-chemical properties (pH and soil water content: SWC), total nitrogen (TN), soil organic carbon (SOC) and microbial biomass (MBC and MBN) by the structural attributes to involve plant N absorption by plant. Where (a) represent structural equation model (SEM) in the dry-cold season for the model were x² = 7.944, p = 0.056, CMIN/df = 1.986, GFI = 0.900, RMSEA = 0.050, CFI = 0.933; and (b) represent SEM in the wet-hot season for the model were x² = 4.663, p = 0.324, CMIN/df = 1.166, GFI = 0.948, RMSEA = 0.026, CFI = 0.974. The black solid lines and dotted lines indicate significant positive and negative relationships, respectively; the thickness of the arrows reflect the degree of relationships, numbers at arrows are standardized path coefficients, and R² values indicate the variation of response variables explained by the model. ^*, ^** and ^*** are different significantly at p < 0.05, p < 0.01 and p < 0.001, respectively