Cold-season freeze frequency is a pervasive driver of subcontinental forest growth

Significance The reduction of freeze exposure with winter warming has consequences for carbon sequestration by northern forests. Quantifying the impact of these changes on tree growth is, however, challenging because of among- and within-tree species variability in freeze tolerance and phenological cues. Here, we provide a comprehensive assessment of tree growth response to the cold-season frequency of freeze days using an extensive tree-ring dataset covering Canada’s forests. Our study shows that tree growth responses to freeze exposure vary in direction and magnitude by clade and species but also with leaf-out strategy, tree age and size, and environmental factors. Such quantification can help predict terrestrial carbon dynamics under climate change.