Fig. 4

Empirical relations between the power model parameters (R ₁ and k) and soil moisture (M) in three subtropical forest soils. R ₁ is the initial respiration, i.e., the starting value of R _h when t = 1; k is the power indicates the rate of R _h change. PE, SS, and CB  in panels a-c represent the P. elliottii plantation, S. superba plantation, and conifer and broadleaf mixed forest soils, respectively. Models of fitting for PE, R ₁ = −3.868 W² + 5.572 W−0.561 (r ² = 0.89), k = −0.165 W² + 0.2659 + 0.162 (r ² = 0.54); for SS, R ₁ = −6.576 W² + 8.403 W−0.979(r ² = 0.76), k = −0.237 W² + 0.304 W + 0.111(r ² = 0.88); for CB, R ₁ = −9.864 W² + 13.214 W−1.907 (r ² = 0.82), k = −0.598 W² + 0.790 W + 0.065 (r ² = 0.99)