Functional traits predict changes in floral phenology under climate change in a highly diverse Mediterranean community

Abstract

Plants are shifting their flowering phenology in response to climate change, but trends differ between species and communities. Functional traits can largely explain how different species respond to climate change by shifting their phenology, and can therefore help predicting which species will be most affected by climate change. Here we studied how functional traits affected the response to climate change of the flowering phenology of 269 species from a Mediterranean community between two periods in the last 35 years. We used circular statistics to assess whether the community means for the start of flowering, start of intense flowering, end of intense flowering, and end of flowering had advanced in the last 35 years. Then, we fitted generalised linear mixed models to assess the influence of vegetative and reproductive functional traits on the shift of the start of flowering, start of intense flowering, end of intense flowering, end of flowering, flowering duration, and intense flowering duration. The flowering phenology of our study community advanced significantly in response to climate change, and both vegetative and reproductive functional traits influenced phenological change. We demonstrated that woody species, short ones, species with wider leaves, high specific leaf area (SLA) values, larger flowers, early flowering, or short flowering periods were advancing more the start of their flowering, while taller plants, species with high SLA values, or early flowering were advancing more the end of their flowering. Consistently, taller species with wider leaves and early flowering species with short flowering time duration were increasing more the duration of their flowering. We showed that phenological shifts associated with climate change are conditioned by functional traits in a different way than previously reported for higher latitudes, indicating that these responses are highly context dependent. In our Mediterranean community, reproductive traits were important for predicting species flowering shifts, indicating that plant species reproduction during the hottest and driest periods of the year—the Mediterranean resting season—may be compromised, along with the persistence of animals that depend on floral resources. Read the free Plain Language Summary for this article on the Journal blog.