Has recent climate change led to changes in phenological synchrony? A meta-analysis

Background/Question/Methods

Variation among species in their phenological responses to temperature suggests that shifts in the relative timing of key life stages between interacting species (phenological synchrony) are likely to occur under climate warming. Altered timing of ecological interactions can have important fitness consequences for one or both species in the interaction. However, the prevalence, magnitude and direction of changes in phenological synchrony in response to recent climatic change are unknown given the variation across studies in their findings and lack of synthesis of the literature. Here, we conducted a meta-analysis using published phenological time-series data for interacting species for the same locations and years to draw generalizable conclusions about whether recent climate change has led to overall changes in phenological synchrony. We defined synchrony as annual differences in the day of year of key phenological phases between interacting species and limited our analysis to cases where the authors were explicit about the presence of an interaction.

Results/Conclusions

Our search yielded phenological data for 60 interactions from 25 studies with time series data that were longer than 5 years. Preliminary results suggest that phenological synchrony has not changed over the past 50 years, even after accounting for the duration of the study. Moreover, there were no significant differences in synchrony between aquatic and terrestrial systems, across biomes or interaction types. Species have advanced their phenologies but the rate of phenological shift has not differed between interacting species. Although interacting species may have different phenological sensitivities to temperature or respond to different cues, our preliminary results suggest that interacting species may maintain phenological synchrony in response to climate change. It remains unclear, however, whether there have been changes in the temporal overlap of key life stages, which could have important implications for species with narrow growing seasons.