Questions: Does succession of rewetted species-poor fen grasslands display similar trends when different water levels, sites and regions are compared? Will restoration targets as peat growth and waterfowl diversity be reached?
Location: Valley fen of the river Peene (NE-Germany) and the Hanság fen (Lake Neusiedler See, NW-Hungary).
Methods: Analysis of permanent plot data and vegetation maps over a period of up to seven years of rewetting. The general relations between newly adjusted water levels and changes in dominance of helophytic key species during early succession are analysed considering four rewetting intensities (water level classes) and eight vegetation types (Phalaris arundinacea type, Carex type, Glyceria maxima type, Phragmites australis type, Typha type, aquatic vegetation type, open water type and miscellaneous type).
Results: The initial period of balancing the site conditions and vegetation is characterised by specific vegetation types and related horizontal vegetation structures. Most vegetation types displayed similar trends within the same water level class when different sites and regions were compared. A significant spread of potentially peat forming vegetation with dominance of Carex spp. or Phragmites as desired goal of restoration was predominantly restricted to long-term shallow inundated sites (water level median in winter: 0–30 cm above surface). Open water patches as bird habitats persisted mainly at permanent inundated sites (water level median in winter > 60 cm above surface).
Conclusions: Site hydrology appeared as a main force of secondary succession. Thus the rewetting intensity and restoration targets have to be balanced adequately.