Assessing plant phenological changes based on drivers of spring phenology

Understanding plant phenological responses to climate warming is crucial
for predicting changes in plant communities and ecosystems, but difficult
with sensitivity analysis that is not linked to drivers of spring
phenology. In this article, we present a new measure phenological lag to
quantify the overall effect of phenological constraints, including
insufficient winter chilling, photoperiod, and environmental stresses,
based on observed response and that expected from species-specific changes
in spring temperatures, i.e., changes in spring forcing (degree days) from
warming and average temperature at the time of species events. We applied
this new analytical framework to a global dataset with 980 species and
1527 responses to synthesize observed changes in spring phenology and
investigate the contributions of forcing change, growth temperature, and
phenological lag to differential phenological responses reported
previously.