Fig. 1: Change in anomalies of intrinsic water use efficiency (W) and dryness (i.e., standardized precipitation-evapotranspiration index, SPEI), and their correlations during the period from 1950 to 2010.
From: Increasing constraint of aridity on tree intrinsic water use efficiency
a Interannual variation of W (black) and SPEI (red) anomalies during the period 1950–2010. Reversed values of SPEI anomaly are shown in the figure. b Change in correlation coefficients (R) between W and SPEI anomalies in each 22-year sliding window. c Change in sensitivity of W to SPEI (SW) in each 22-year sliding window. Shaded areas in (b) and (c) indicate 95% confidence intervals in t-tests for each sliding window. Source data are provided as a Source Data file.
