Abstract

In 2023, more than half of olive harvests (Olea europaea) across Spain, Greece, and Türkiye were lost to drought. The same yearlate freeze destroyed 90% of the peach crop (Prunus persica) on the Georgia Piedmont and the apple crop (Malus domestica) incentral New York, Vermont, and southern Quebec. Climate extremes now rank with the costliest threats to agriculture, buttheir role in forest recovery from diebacks that are happening globally is unknown for lack of tree fecundity estimates in for-ests. Tolerance of climate extremes could depend on past exposure but constrained by phylogenetic conservatism. We report acontinental scale analysis of climate extremes and forest fecundity across North America and Europe showing that responsesto late freeze and drought are happening now. Species differences are not explained by the traits typically included in ecologicalstudies and they are weakly associated with phylogeny. Late freeze, that is, freezing temperatures that follow the onset of flowerdevelopment in spring, is shown to be “normal” in North America, but not Europe, potentially explaining failed seed productiondue to delayed onset and the resultant shorter growing period by North American transplants dating back at least to the 18thcentury. Drought has thus far had the greatest impacts in dry forested regions, but here too, species differences are not explainedby traditional trait values. If responses have been buffered from drought and late freeze by past exposure, acclimation and localadaptation prove inadequate as extremes intensify.