Effects of restoration measures on plant communities of wet heathland ecosystems

Question: Which are the success and failure of restoration measures, particularly sod-cutting and hydrological measures, in small wetlands on mineral soils in The Netherlands.Location: Twente, in the eastern part of The Netherlands.Methods: Success or failure of restoration measures has been assessed by comparing experimental plots with that in reference plots for (1) species richness, (2) re-establishment of endangered species and (3) species composition, including life forms and Red List species. In total 119 samples were taken in 42 permanent plots in fen meadows, small-sedge marshes, wet heathlands, and soft-water pools. Topsoil samples were analysed for pH, Ca, Mg, Na, K and Cation Exchange Capacity. Gradient analysis was carried out by means of Canonical Correspondence Analysis.Results: Sod-cutting, in combination with re-wetting measures (infilling of ditches and drains), led to restoration of communities of soft-water pools and small sedge marshes within five years. This rapid recovery is probably related to the presence of persistent seed banks of the component species of these communities. Complete restoration of fen meadows took longer (10––15 yr). Apparently, many species of fen meadows have short-lived seed banks. Sod-cutting of a degraded wet heathland and a soft-water pool was only successful temporarily, probably as a consequence of low water tables.Conclusions: To prevent depletion of (persistent) soil seed banks, sod-cutting in nutrient-poor wetlands is not recommended in areas where the groundwater regime and the base status of the soil can not be restored to levels required by plant communities of wet heathlands.Nomenclature: van der Meijden (1990) for phanerogams, Smith (1980) for mosses and Schaminéée et al. (1995, 1996) for syntaxa.Abbreviations: AAS == Atomic absorption spectometry; CEC == Cation exchange capacity; H⁺⁺ exch == Exchangeable H⁺⁺; WC == Water content.