Partial recovery and uneven ecological responses of beetles following mire rewetting in central Sweden

Sammanfattning

Mires support specialised biodiversity and important ecosystem functions, but many have been degraded by drainage for forestry, agriculture and peat extraction. Rewetting is widely used to reverse mire degradation by restoring water levels, yet its ecological effects remain incompletely understood, particularly for diverse insect groups. Because insects are species-rich, ecologically complex and often sensitive to environmental change, they may provide useful indicators of rewetting outcomes. In this study, I evaluated rewetting effects on beetle assemblages across 18 mires in central Sweden, including ditched, rewetted and unditched sites. Beetles were sampled using pitfall and window traps and identified to species level, enabling ecological comparisons among mire types. Environmental variables were also included to assess their contribution to the observed ecological patterns. Rewetted mires showed partial and uneven ecological responses, with some patterns closer to unditched mires and others closer to ditched mires. Wetland species richness in rewetted mires was closer to unditched conditions, whereas generalist abundances remained more similar to ditched mires. In contrast, terrestrial species and feeding guilds showed little or no response to rewetting. Environmental variables provided limited explanatory power for the observed patterns. Overall, beetles appear useful for detecting ecological responses to rewetting, although the results suggest partial rather than complete recovery.