Climate‐induced shifts in long‐term tropical tree reproductive phenology: Insights from species dependent on and independent of biotic pollination

Abstract The dependence on biotic pollination may constrain plant phenological responses because flowering time ultimately defines reproductive success. We proposed a local‐scale study combining long‐term phenology and experimental data to evaluate how a key functional trait—the dependence/independence on biotic pollination for reproduction—influences the phenological response of tropical plants to a locally shifting climate. We asked whether the flowering and fruiting durations and start and peak dates of trees differed over time according to the dependence or independence on biotic pollination; if species dependent on biotic pollination are more responsive to climate; and how phenological shifts affect co‐flowering and the proportion of flowering individuals producing fruits (reproductive success). Our study was conducted in a diverse Cerrado savanna vegetation where long‐term phenological monitoring has been conducted since 2004. We selected the 31 most‐abundant tree species, monitored from 2005 to 2019 and categorized them by pollination type, reproductive system and functional group (dependent/independent on biotic pollination). We applied generalized linear mixed models to test whether flowering and fruiting variables differ over time according to functional group and local climatic variables. We used circular statistics to extract phenological parameters and evaluate phenological changes between functional groups. We analysed species co‐flowering and the proportion of flowering individuals that produced fruits over time, according to their dependence on biotic pollination and a changing climate. Decreasing precipitation was the key driver determining the significant reduction in flowering duration, and temperature and relative humidity drove the decrease in fruiting duration for both functional groups. Overall, co‐flowering decreased over time, but reproductive success of both functional groups did not change, suggesting community resilience to the changing climate. We highlight the relevance of reductions in flowering and fruiting durations for tropical plants in contrast to the widespread early flowering observed for species from North temperate regions in response to climate change. Reduced duration of reproduction and increased flowering decoupling across species pairs did not affect the estimated reproductive success of either functional group. However, those responses may have far greater consequences for plant–pollinator and plant–frugivore interactions, by reducing or changing resource availability over time in highly diverse tropical savannas. Read the free Plain Language Summary for this article on the Journal blog.