Warming sensitivity of spring phenology of deciduous species lies in their bud energy budget

Abstract

Spring phenology is mainly driven by temperature in extratropical ecosystems. Contrasting responses of foliar phenology to climatic warming, however, have been reported in recent decades, raising important questions about the role of other environmental constraints, especially light. In fact, temperatures differ substantially between plant tissues and the air because plants absorb and lose energy. Yet, phenology studies always substitute plant tissue temperature by air temperature. Here, we explored how solar radiation, wind, and bud traits might affect spring phenology of deciduous forests through the energy budget of buds. We show that air temperature might be an imprecise and biased predictor of bud temperature. Our current interpretation of the plant phenological response to warming should be reconsidered, which will require new observations of bud traits and temperature for accurately quantifying their energy budget.