Figure Legends
Fig. 1 (a) Annual mean temperature, (b) annual precipitation of the growing season (June to September), and (c) the De Martonne Index (DMI) reflecting environmental aridity of the study area for the period of 1970-2019. The solid line in panel a shows a significant trend of temperature increase, the dashed lines in panel b, c show the average of annual growing seasonal precipitation and DMI for 1970-2019, and the shaded area in panel c indicates the -1.5 times standard deviation of DMI. Data were from Zhangwu meteorological station located about 31 km from the study site.
Fig. 2 The change of cumulative basal area (CBA) with tree cambial age for each studied conifer species. The dashed vertical line marks the age of 15 years and the number in the upper right corner of each panel shows the CBA value at a cambial age of 15 years (CBA15) for each species. Species name abbreviations are as shown in Table 1.
Fig. 3 Standardized tree-ring width chronologies (red lines) of the seven studied tree species. The blue line in each of the left panels shows the number of cores in specific years. The panels on the right show standardized tree-ring width indices during, before and after the 2015 drought event. Species name abbreviations are as shown in Table 1.
Fig. 4 (a) Net photosynthetic rate on per leaf dry mass basis (A m) and (b) sapwood-specific hydraulic conductivity (K s, gray bars) and leaf-specific hydraulic conductivity (K l, black bars) of the seven studied conifer species. Error bars show 1SE (n = 8). Species name abbreviations are as shown in Table 1. Results of one-way analyses of variance are shown in each panel.
Fig. 5 (a) hydraulic safety margin (HSM), (b) wood density (WD) and leaf osmotic potential at zero turgor (π 0). Error bars show 1SE (n = 18-24 for WD, n = 8-10 for HSM and π 0). Species name abbreviations are as shown in Table 1. Results of one-way analyses of variance are shown in each panel.
Fig. 6 Correlations between tree drought resistance index (RT), resilience index (RS) and (a, d) wood density (WD), (b, e) hydraulic safety margin (HSM) and (c, f) leaf osmotic potential at full turgor (π 0). Horizontal error bars show ± 1SE (n = 18-24 for WD, n = 8-10 forπ 0). Symbols are as defined as in Table 1.
Fig. 7 Correlations between tree drought resistance index (RT), resilience index (RS) and (a, c) leaf-specific hydraulic conductivity (K s) and (b, d) net photosynthetic rate on per leaf dry mass (A m). Horizontal error bars show ± 1SE for K s and A m, respectively (n = 8). Symbols are as defined as in Table 1.
Fig. 8 Correlation between the cumulative basal area at cambial age of 15 years (CBA15) and mean sensitivity from tree-ring analysis across the seven studied conifer species. Symbols are as defined in Table 1.