Abstract Detail

Ecology

Herbarium specimens and citizen science data reveal shorter flowering duration over time in spring, but not fall, blooming plants.

A significant body of work has shown a strong overall trend toward earlier spring flowering over time due to climate warming. However, far less is known about temporal trends in timing of flowering offset and duration, due to a paucity of historical data monitoring. If flowering onset and cessation respond differentially to climatic changes, this could increase phenological mismatches with pollinators and affect plant fitness. Recent work has shown that flowering duration is longer in warmer regions, especially for summer-blooming compared to spring-blooming species, driven by strongly differing offset dynamics. However, it is not known if these same trends in offset and duration manifest over time. Here we derive flowering onset, offset and duration estimates from two different data sources: 1) digitized herbarium specimens annotated for presence of flowers in mostly understory plants in North America and; 2) citizen science reporting of flowering of canopy species in Europe. In sum, these data resources provide the basis for making predictions for more than 180 species over 100 years of sampling. Utilizing a series of best practices and new methods for presence-only data, along with phylogenetic linear mixed models, we uncover consistent evidence supporting previous results for temperature-driven increases in flowering duration; however, these are counterbalanced by an equally consistent trend across all datasets towards shortening duration over time for spring blooming plants, whether understory or canopy. In contrast, later-season blooming plants show trends towards longer durations over time, even after accounting for climate. In sum these results showcase that simple space for time substitutions may miss critical aspects of species response to climate change, and show instead that plants are shifting flowering onset and offset phenological sensitivities over time.

1 - Florida Museum Of Natural History, 358 Dickinson Hall, University O, 358 Dickinson Hall, University Of Florida, Gainesville, FL, 32611, United States

Keywords:
phenology
Environmental change
Citizen Science
Herbarium
flowering.

Presentation Type: Oral Paper
Number: EC05003
Abstract ID:958
Candidate for Awards:None