Fig. 10: Nonlinear effects of SWUE-C-F on EPI.

This figure describes the nonlinear effects of the SWUE-C-F system on EPI in 1985 (Subplots a–c), 2000 (Subplots d–f), and 2010 (Subplots g–i). Three carbon layer values (C = 65.55, C = 167.90, C = 269.92) are obtained from the statistical analysis of a total of 10,128 carbon storage grid cells (with a spatial resolution of 10 × 10 km) across three periods: 1985, 2000, and 2010. Specifically, C = 65.55 represents the overall mean value of carbon storage data minus one overall standard deviation, C = 167.90 represents the overall mean value of carbon storage data, and C = 269.92 represents the overall mean value of carbon storage data plus one overall standard deviation. Solid red arrows indicate the response of EPI to different SWUE and F values across different periods under the same carbon layer level for the corresponding column in the figure. Subplots (a) to (c) illustrate the nonlinear effects of the SWUE-C-F system on EPI in 1985, 2000, and 2010 when C = 65.55; Subplots (d) to (f) illustrate the nonlinear effects of the SWUE-C-F system on EPI in 1985, 2000, and 2010 when C = 167.90; Subplots (g) to (i) illustrate the nonlinear effects of the SWUE-C-F system on EPI in 1985, 2000, and 2010 when C = 269.92. In Subplots a–i, the brightness of yellow in the figure is positively correlated with the EPI value, i.e., the higher the brightness of yellow, the greater the corresponding EPI value; in contrast, blue shows the opposite trend: the lower the brightness of blue, the smaller the corresponding EPI value.