Peat Disturbance, Mowing, and Ditch Blocking as Tools in Rich Fen Restoration

Abstract

Among wetlands, rich fens are one of the most species‐rich, and also one of the most threatened habitats due to drainage activities. We tested the effects of several restoration measures on vegetation composition and dynamics over 4 years in two rich fens in east central Sweden that had been drained about 50 years ago. The encroaching tree layer was removed, and the restoration measures examined were rewetting by ditch blocking, mowing, and peat disturbance (removing vegetation and mixing the surface peat). At both sites, rewetting alone (without mowing or peat disturbance) led to small changes in species composition. In plots with peat disturbance, several characteristic rich fen species established, probably from a persistent diaspore bank or from refugia nearby. The disturbance treatment also prevented a rapid reestablishment of dominant grasses and mosses that had spread since drainage. Late season mowing alone appeared not to be a very efficient treatment in the initial phase after restoration, but seemed to reinforce the positive effects of peat disturbance. The results indicate the necessity of combining several treatments to recreate an ecologically functional vegetation.