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

Spatial variation in species interactions (interaction β-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 β-diversity in plant-bee communities
across three localities in the Northern Rocky Mountains (Montana, USA).
Wildfires decreased interaction β-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 β-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 β-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.