Discordant changes in foliar and reproductive phenology of tropical dry-forest trees under increasing temperature and decreasing wet-season rainfall

Abstract

SummaryPlant phenology drives population demography and ecosystem functioning. We urgently need to better understand whether species and communities can cope with changing environmental cues of phenology, especially in tropical dry forests that may experience more droughts.We analysed long-term monthly foliar and reproductive phenology (2003–2021) of 623 trees across 94 taxa in a seasonally-dry Afromontane forest in Nigeria and related them to climate trends (1976–2023).We found decreasing trends in leaf flush and fruit production, but leaf shedding has increased. Community synchrony decreased markedly for leaf shedding but increased for fruiting.These phenological trends corresponded to signs of increased aridity. Minimum temperature has increased, with greater warming in the dry and intermediate seasons than the wet season. Rainfall fluctuated, but the dry season has become significantly wetter and the wet season drier.Our study highlights the discordant trends in foliar and reproductive phenologies. Fewer fruits and increasing leaf shedding indicate reduced productivity that will impact frugivores and nutrient cycling. More asynchronous leaf shedding suggests a decoupling from leaf flush and reproduction, potentially disrupting ecosystem regimes. Interspecific variation in response to climate change implies forest composition may shift towards the dominance of deciduous species.