In a remarkable study, Matt Austin, a former postdoc in the Global Change & Conservation Lab (and now the Missouri Botanical Garden’s first Biodiversity Data Curator!) “collaborated” with Edgar Anderson who, 80 yr ago, surveyed prairies and woodlands outside of Saint Louis, Missouri. Matt found that climate change has phenologically reassembled the plant community in surprising ways. In the 1940s, there were two peaks of richness in species that were flowering–one in the spring and one in the fall. Now, however, there are three, caused by some of the fall-flowering species flowering even later, inducing a third “hump” in co-flowering richness. Some species even increased the duration of their flowering by more than an entire month! Notably, this research combined field observations and herbarium records to estimate changes in first and last flowering date.
Climate change increases flowering duration, driving phenological reassembly and elevated co-flowering richness [article]
Austin, M.W., Smith, A.B., Olsen, K.M., Hoch, P.C., Krakos, K.N., Schmocker, S.P., and Miller-Struttmann, N.E. 2024. New Phytologist 243:2486-2500.
Abstract. Changes to flowering phenology are a key response of plants to climate change. However, we know little about how these changes alter temporal patterns of reproductive overlap (i.e. phenological reassembly). We combined long-term field (1937–2012) and herbarium records (1850–2017) of 68 species in a flowering plant community in central North America and used a novel application of Bayesian quantile regression to estimate changes to flowering season length, altered richness and composition of co-flowering assemblages, and whether phenological shifts exhibit seasonal trends. Across the past century, phenological shifts increased species’ flowering durations by 11.5 d on average, which resulted in 94% of species experiencing greater flowering overlap at the community level. Increases to co-flowering were particularly pronounced in autumn, driven by a greater tendency of late season species to shift the ending of flowering later and to increase flowering duration. Our results demonstrate that species-level phenological shifts can result in considerable phenological reassembly and highlight changes to flowering duration as a prominent, yet underappreciated, effect of climate change. The emergence of an autumn co-flowering mode emphasizes that these effects may be season-dependent.
