Wildfire severity alters drivers of interaction beta-diversity in plant-bee networks

Spatial variation in species interactions (interaction beta-diversity) and its ecological drivers are poorly understood, despite their relevance to community assembly, conservation and ecosystem functioning. We investigated effects of wildfire severity on patterns and four proximate ecological drivers of interaction beta-diversity in plant-bee communities across three localities in the northern Rocky Mountains (Montana, USA). Wildfires decreased interaction beta-diversity but increased interaction frequency (number of visits) and richness (number of links). After controlling for interaction frequency and richness, standardized effect sizes of interaction beta-diversity were highest following mixed-severity wildfires, intermediate following high-severity wildfires and lowest in unburned landscapes, suggesting that wildfire increases spatial aggregation of plant-bee interactions. Moreover, higher effect sizes in burned landscapes were largely determined by turnover in the species composition of both trophic levels rather than by interaction rewiring (spatial turnover in local species interactions not due to species turnover). The underrepresented level of rewiring indicated spatial consistency in post-disturbance patterns of interactions among co-occurring species. Together, our findings suggest that wildfire alters the beta-diversity of mutualistic species interactions via linked assembly of plant-bee communities and provide insights into how environmental change alters complex networks of species interactions.

Automated summary

This study investigates the effects of wildfire severity on the diversity of plant-bee community interactions. The results show that wildfires decrease interaction beta-diversity but increase interaction frequency and richness. Moreover, the increase in beta-diversity in burned landscapes is primarily driven by turnover in species composition. These findings provide insights into how environmental change alters species interactions.