Fig. 4.

Observed and modeled FFD trends (d⋅y⁻¹) for the 70 divergent responders at Chinnor. Observed trends in FFD are colored gray, modeled FFD trends using only spring warming sensitivities are colored green, and modeled FFD trends using spring warming and vernalization sensitivities are colored blue (n = 70 species). The observed trends are centered on zero, and trends for the models incorporating vernalization sensitivity are similarly centered. If only the spring warming predictors are considered for these species, modeled trends are biased negative, predicting a general advance in the timing of FFD that is at odds with the observations. Including vernalization sensitivity as well as spring warming sensitivity improves the ability of the model to reproduce the observed temporal FFD trends.