Fig. 3.

Predicted changes in δ¹⁸O_TR from a changes in moisture inflow and large-scale rainfall amount, b change in vapor pressure deficit, and c reductions in stomatal conductance (g_s). Panel (a) shows the predicted relationship between δ¹⁸O_rainfall and accumulated rainfall relative to the total moisture inflow in 1970 (%) using a Rayleigh model. The thin line simulates a baseline Rayleigh model (i.e. starting with 100% moisture inflow), while the thick line simulates a model with 15% greater inflow to replicate the observed and modelled increase in inflow and modelled changes in δ¹⁸O from 1970 and 2014, indicated by the gray arrow (see Online Resource SIFig. 6). The value of − 4.5‰ is the δ¹⁸O of “dry season” rainfall at the sampling site. Note that accumulated rainfall amounts also account for 50% recycled rainfall, so the value of 1 corresponds to approximately 50% fractional rainout for 1970, and 44% for 2014. Expectations in (b, c) were based on tree-ring isotopes models (e.g. Cintra et al. 2019), with the black and gray lines indicating a path length of 0.01 and 0.02, respectively. See “Methods” section for details on the models used