Fig. 2

Modeled xylem ring width and growth rate of C. chinensis in CK and CN in 2015 (left panel) and 2016 (right panel). Based on observed xylem ring width (mm), Gompertz function was used to simulate the intra-annual xylem growth pattern of C. chinensis and its derivate was calculated as the growth rate (μm/day). Black dots and red dots represent observed xylem width in CK and CN, respectively. The black line and the red line represent simulated xylem width in CK and CN, respectively. CK and CN represent control and N-treated trees