If we build - they mostly come: partial functional recovery but persistent compositional differences in wetland beetle community restoration

There is growing evidence of restoration success for wetland plant communities. However, little research has been done on the associated invertebrate community. We testwhether restoring plant communities after peat extraction is sufficient for restoring the taxonomic and functional composition of beetle communities. We monitored taxonomic and trait-based community metrics for beetle assemblages on restoration islands that were up to 13 years old and compared these with the adjacent target undisturbed peat bog. Recovery of beetle abundance, species richness, and trophic structure on the islands was remarkably rapid (i.e. within a decade) and converged on that of the undisturbed peat bog within 13 years after restoration commenced. In contrast, small, native, and poor-dispersing taxa were persistently less abundant on the islands than in the undisturbed peat bog, causing persistent differences in species composition, even on the oldest islands. These poor-dispersers probably need assistance to reach the islands and possibly ongoing intervention to allow them to survive there. Our findings emphasize the potential for functional trait analysis to reveal barriers to full restoration of insect community composition.