Divergent responses of leaf phenology to changing temperature among plant species and geographical regions

Abstract

Shifts in plants' phenophases caused by climate change can strongly affect the ecosystem structure and function. Temperature sensitivity, which is expressed as the date of phenological event change for per degree Celsius change of temperature (days 8C ô1 ), has been widely used to characterize the plants' responses to changed temperature. In this study, we analyzed the temperature sensitivity of leaf phenology (leaf unfolding date, LUD; leaf falling date, LFD) for more than 700 plant species based on the phenological observations at 56 sites in China from 1963 to 1988. Our results suggested significant spatial and interspecific variations in the responses of leaf phenology to changing temperature. Approximately 48.8% cases of LUD advanced significantly (p , 0.1) with the increasing spring temperature and 33.9% cases of LFD delayed significantly with increasing autumn temperature. The spring events were overall more sensitive to temperature than autumn events. Although the LUD of plants in warmer regions was more sensitive to changing temperature, the temperature sensitivities of LFD for plants in warmer regions were not significantly different from that for plants in cooler regions. Moreover, for spring phenology, many sites suggested higher temperature sensitivity for species that unfold their leaves earlier. For autumn phenology, species with later leaf-falling dates were generally more sensitive to temperature. Differences in species' responses to temperature that caused the discrepant changes in species' growing season can strongly impact vegetation dynamic and ecosystem function, and thus should be considered more when predicting the effects of climate warming on the biosphere.