Responses of insect pollinators to habitat fragmentation: A global meta‐analysis

Abstract Insect pollinators are declining globally, with habitat fragmentation recognised as an important driver. While these declines have garnered widespread public and policy attention, current evidence remains largely limited to certain taxa, geographic regions and ecosystems, thereby resulting in diverse outcomes. Here, we aimed to present a global meta‐analysis using a dataset comprising 80 studies across 28 countries on all continents, excluding Antarctica. We used Pearson's correlation coefficient ( r ) as an effect size to measure the association between habitat fragmentation and the abundance and species richness of wild bees, butterflies and wasps. Subsequently, we performed categorical meta‐analyses that used fragmentation indices, climates and taxonomic groups as moderators to investigate the dependency of habitat fragmentation effects on these factors. Increasing habitat fragmentation was significantly associated with reductions in both the abundance ( r = −0.26, 95% CI: −0.39, −0.12) and species richness ( r = −0.46, 95% CI: −0.55, −0.35) of insect pollinators. The magnitude of these associations varied depending on the evaluated fragmentation index. Specifically, pollinator abundance ( r = −0.43, 95% CI: −0.56, −0.29) and species richness ( r = −0.62, 95% CI: −0.71, −0.52) significantly decreased with reduced habitat area. Synthesis and applications. Our results show that insect pollinators have declined globally due to habitat fragmentation. Reduced habitat area was the main driver of pollinator decline. The findings indicate that preserving large habitats can support more insect pollinators. This implies that policies must target the landscape scale to mitigate the negative effects of habitat fragmentation.