The response in woody plant budburst date to temperature and photoperiod cues across North America

Background/Question/Methods

The timing of spring phenological events is advancing for many plant species, altering the length of the growing season, plant community structure, and ecosystem services. Understanding the primary drivers of these shifts is therefore of great importance. Previous work in woody plant systems have identified three primary cues for the start of spring development — winter chilling, spring forcing, and photoperiod. These cues, however, interact and their relative importance varies across species, making accurate predictions for future changes challenging. In this study, I combined phenological data from two growth chamber experiments to test the relative importance of these three cues across two woody plant communities and along two latitudinal transects in North America.

Results/Conclusions

All species advanced in response to these cues, while also varying in their relative sensitives. We observed the strongest responses to forcing and chilling cues, while responses to photoperiod varied more across species. Our eastern and western transects also differed in their cue responses, and further differences were found between woody tree and shrub functional groups. Our results highlight the importance of using experiments to test species cue responses and the complexity of the mechanisms with which species track and respond to their environments. These findings also provide insights into how species may respond to changes in temperature and the data needed to accurately predict changes in community composition and novel species interactions.