Fig. 3: The temperature response of ²H and ¹⁸O.

The isotope response to temperature of Δ²H and Δ¹⁸O in leaf water and leaf sugar, and ε_HA and ε_OA, the apparent ²H and ¹⁸O fractionation between leaf water and leaf sugar. Values are given as Δ; e.g., normalized to average δ values measured at 10 °C individually for each species. The lines represent the quadratic (²H) respectively the linear model (¹⁸O) depicting the relationship between temperature and Δ and ε values, the lighter shading denotes the 95% confidence level interval for predictions of the quadratic and linear fit, R², and p values as well as the corresponding functions for the temperature response (i.e., ‰ at a given temperature) values inform on the temperature relationship of the variables.