Successional and phenological effects on plant-floral visitor interaction networks of a tropical dry forest

1. Plant-pollinator interactions are fundamental to ecosystem functioning; however, the role that succession and phenology have on these interactions is poorly understood, particularly in endangered tropical ecosystems. In highly diverse ecosystems such as tropical dry forests (TDF), variation in water and food availability determines the life cycles of animal pollinators. Therefore, understanding patterns of flowering phenology and plant-pollinator interactions across seasons in successional environments is key to maintaining and restoring TDF.2. We analysed the functional dynamics of plant-floral visitor interactions at the community level across a successional gradient in a Mexican TDF. We evaluated changes in the diversity of blooming plant species and floral visitors, phenological patterns, interaction network metrics and beta diversity among early, intermediate and late successional stages, between dry and rainy seasons.3. We found a higher diversity of blooming plant species and a higher richness of animal species in the intermediate and late successional stages. Peak abundance of floral visitors overlapped with flowering peaks in the late successional stages, but this was not consistently the case in the early and intermediate stages. Plant floral visitors networks differed in structure according to successional stage and season, but specialisation metrics were higher in late successional stages. Interaction networks were more dissimilar between dry and rainy seasons within successional stages than within seasons between successional stages, suggesting connectivity across successional sites during each season. In addition, closely related plant species do not share the same pollination systems in any successional stage.4. Synthesis. Our results showed that plant-floral visitor interactions are dynamic and vary with flowering phenology and with successional changes in plant and animal diversity. Plant-floral visitor interactions were more diverse and specialised in the late successional stages. In the rainy season, differences in network structure among successional stages are due to interaction rewiring, while in the dry season, it is caused by species turnover. Our results demonstrate that seasonality plays a key role in community diversity and network structure and highlight the importance of conserving mature forests to ensure the maintenance of critical pollination interactions across all successional stages.

Automated summary

The role of succession and phenology in plant-pollinator interactions in endangered tropical ecosystems, particularly in tropical dry forests, is poorly understood. This study investigates the patterns of flowering phenology and plant-pollinator interactions across different successional stages and seasons, highlighting the importance of conserving mature forests to ensure critical pollination interactions.