Mass Flowering and Flowering Asynchrony Characterize a Seasonal Herbaceous Community in the Western Ghats

Abstract

Flowering synchrony within a community may be facilitated by climatic factors and by ecological interactions that promote shared pollination services. In contrast, flowering asynchrony is promoted when there is inter-species competition for pollinators. Here, we investigate the flowering phenology of a seasonal, herbaceous community (Kaas plateau) in the Western Ghats, India, to identify the presence of synchrony and mass flowering. We addressed the following questions: (a) Is flowering seasonality correlated with climatic factors? (b) Is there evidence for flowering synchrony or floral colour-based synchrony within the community? (c) Do plant-pollinator interactions shift with flowering phenology? In Kaas, we recorded the flowering phenology of 76 herbaceous species and found that climatic factors influenced their flowering phenology. We also identified the community to be composed of a few mass flowering (MF) species (~30%) and several non-mass flowering (nMF) species (~70%). Using two novel synchrony indices, temporal overlap (SI_temp) and synchrony in abundance (SI_abd), we also identified higher asynchronous flowering within the community than expected. Notably, species sharing the same floral color showed a marked absence of synchrony, thus suggesting that competition and not pollinator-mediated facilitation drives flowering asynchrony within Kaas. Finally, pollination networks were observed to shift with flowering abundances within the community. Our findings reveal that even seasonal landscapes like the laterite plateaus, despite their short flowering season that lasts only 4–5 months, exhibit an overall asynchronous flowering phenology. The Kaas plateau, famous for its spectacular flowering displays, achieves this apparent synchrony primarily through a few mass flowering species that vary across years.