Temperature controls phenology in continuously flowering Protea species of subtropical Africa

Abstract

Premise of the Study Herbarium specimens are increasingly used as records of plant flowering phenology. However, most herbarium‐based studies on plant phenology focus on taxa from temperate regions. Here, we explore flowering phenologic responses to climate in the subtropical plant genus Protea (Proteaceae), an iconic group of plants that flower year‐round and are endemic to subtropical Africa. Methods We present a novel, circular sliding window approach to investigate phenological patterns developed for species with year‐round flowering. We employ our method to evaluate the extent to which site‐to‐site and year‐to‐year variation in temperature and precipitation affect flowering dates using a database of 1727 herbarium records of 25 Protea species. We also explore phylogenetic conservatism in flowering phenology. Results We show that herbarium data combined with our sliding window approach successfully captured independently reported flowering phenology patterns ( r = 0.93). Both warmer sites and warmer years were associated with earlier flowering of 3–5 days/°C, whereas precipitation variation had no significant effect on flowering phenology. Although species vary widely in phenological responsiveness, responses are phylogenetically conserved, with closely related species tending to shift flowering similarly with increasing temperature. Discussion Our results point to climate‐responsive phenology for this important plant genus and indicate that the subtropical, aseasonally flowering genus Protea has temperature‐driven flowering responses that are remarkably similar to those of better‐studied northern temperate plant species, suggesting a generality across biomes that has not been described elsewhere.

Early spring warming may hasten leaf emergence in Erythronium americanum

“…One result of this general warming trend is changes in the timing of the onset of seasons, including the arrival of spring (Groffman et al., ; Wilson, ). In response to this warming, some species have adjusted the timing of life history events including egg hatching, migrations, flowering, and fruiting (Badeck et al., ; Forrest et al., ; Wipf, ; Hänninen and Tanino, ; Wilson, ; Hansson et al., ; Bertin, ; Jacques et al., ; CaraDonna et al., ; Groner et al., ; McDonough MacKenzie et al., ; Rice et al., ; Daru et al., ).…”

Impediments to Understanding Seagrasses’ Response to Global Change

“…This can influence conclusions drawn from analyses of such non-randomly sampled collections records (Syfert et al, 2013). Temporal data is increasingly used in a wide range of applications in ecology and evolutionary studies including tracking changes in phenology -the timing of seasonal events such as flowering, leafing, and fruitingand monitoring the spread of invasive species (Iler et al, 2013;Veeneklaas et al, 2013;Daru et al, 2019;Meerdink et al, 2019). Yet, while there is general agreement that climate change can influence phenological patterns by disrupting the timing of life cycle events and consequently drive changes in fitness and population demography (Ovaskainen et al, 2013;CaraDonna et al, 2014;Thackeray et al, 2016;Kharouba and Wolkovich, 2020), most have been observed in terrestrial species and to a lesser extent in marine flowering plants.…”

Emerging frontiers in phenological research

“…However, ectomycorrhizal fungal richness was found to have a positive association with tree species richness and saprotrophic fungal richness was not. Daru et al (2019) examined a taxonomically understudied taxon, Protea L., in a phenologically understudied part of the world-subtropical Africa. Importantly, they found that even these botanically unique Protea species respond phenologically to temperature in ways that are similar to northern temperate species.…”

“…Daru et al. () examined a taxonomically understudied taxon, Protea L., in a phenologically understudied part of the world—subtropical Africa. Importantly, they found that even these botanically unique Protea species respond phenologically to temperature in ways that are similar to northern temperate species.…”

“…They find that PhenoCam data provide robust information for their analyses and that ecotypes vary in how strongly they follow the Bioclimatic Law. Integrating data from image‐based studies (e.g., Richardson et al., ) with data from herbarium‐based studies (e.g., Daru et al., ; Ellwood et al., ; Park et al., ), and even aggregating data between studies with similar data sources, can be a challenge due to the many ways phenology can be described. Fortunately, a standardized, relational vocabulary is being developed in the Plant Phenology Ontology (PPO), which enables integration of phenological data across platforms, data sources, and species (Stucky et al., ).…”