Riverine fen restoration provides secondary habitat for endangered and stenotopic rove beetles (Coleoptera: Staphylinidae)

Peatlands have undergone dramatic changes through anthropogenic activities in the last centuries, causing a substantial loss of fen-specific biodiversity. Therefore, restoration of already degraded stands is an important conservation issue. The effectiveness of fen restoration was evaluated through rewetting in the valley of the river Peene, NE Germany, by comparing three fen types: drained fens, rewetted fens, and near-natural fens. Rove beetles (Coleoptera: Staphylinidae) were used as indicators, comprising an ecologically important yet understudied insect group. 5,398 individuals from 121 staphylinid species were recorded by 30 pitfall traps per fen type, which were biweekly emptied between April and October 2012, and related to environmental parameters. Rove beetle assemblages differed markedly between fen types. Community structure was affected by peat degradation, the extent of organic matter, water level, and vegetation height. Fen rewetting favoured the establishment of a distinct, species-rich beetle community within 15years only, caused by an increase in hygrophilous wetland species partially replacing generalists. Nevertheless, this time span was not sufficient to restore communities characteristic for near-natural fens, which harboured several particularly sensitive species that were not found on rewetted fens. Rewetting provided suitable habitats for a substantial number of stenotopic and threatened staphylinid beetles. Thus, the protection of pristine habitats along with restoration measures are both important strategies in peatland conservation.