Dependence of plant phenological responses to climate warming on spring temperatures

Background/Question/Methods

Plant phenological responses to climate warming differ among species with differing spring phenology, between low and high latitudes and altitudes, between observations and experiments, and between exotic and native species, raising concerns on the potential ecological implications and methodological biases. We assessed the effects of a moderate climate warming (from current 1981–2010 baseline to 2 °C warmer) on the responses of hypothetical species without chilling restriction and plant species with different chilling and forcing requirements in different parts of the globe, along with a meta-analysis of global phenological studies.

Results/Conclusions

In both cases, early season species changed more in timing of spring phenology, but gained fewer forcing temperatures from phenological shifts, due to early and cold spring when these species start to grow. The strong dependence of plant phenological changes on spring temperatures helps explain the greater phenological response/sensitivity in early season species and areas of high latitudes and altitudes, as well as the differences between observational studies and warming experiments and among species of different functional groups. Other than different chilling requirements between exotic and native species, reported differences in phenological responses are due to different environmental conditions, i.e., temperatures, warming, and moisture stress, where phenological studies are conducted.