In temperate regions with unpredictable seasonal progression, plants rely on a combination of signals to guide when to unfold their leaves. Relying on temperature only and unfolding during an early warm spell means risks of frost damage, however, waiting too long means missing out on early carbon gain. Integrating additional signaling from day length and winter chilling, especially, provides a more robust strategy.
In this study, researchers investigate differences in leaf-out strategies among Northern Hemisphere woody plants and how they relate to spring temperature predictability in East Asia, Europe, and North America. By combining experimental and monitoring data for a large representative set of species, they reveal continental-scale differences in leaf-out strategies, as plants from North America with high spring temperature variability have much higher winter chilling requirements than related species in East Asia with low spring temperature variability.
The differences in phenological strategies suggest that species’ reactions to climate warming may vary depending on continent, highlighting the importance of considering regional climate histories in models of global change.