Mass flowering and flowering asynchrony characterise a seasonal herbaceous community in the Western Ghats

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. In this multiyear study, we
analyse the flowering phenology of a seasonal, herbaceous community (Kaas
plateau) in the Western Ghats, India to identify environmental constraints
that may influence flowering synchrony. We addressed the following
questions: (a) Is flowering seasonality correlated with climatic factors?
(b) Is there evidence for flowering synchrony within the community?, and
(c) Do plant-pollinator interactions shift with flowering phenology? In
Kaas, we recorded 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 (SItemp) and synchrony in
abundance (SIabd), we also identified higher asynchronous flowering within
the community than expected. Notably, species sharing the same floral
color, showed 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 last 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.