Individual study: Restoration measures so far fails to rehabilitate aquatic macroinvertebrate faunal diversity in raised bogs in the eastern Netherlands
van Duinen G.A., Brock A.M.T, Kuper J.T., Leuven R.S.E.W., Peeters T.M.J., Roelofs J.G.M., van der Velde G., Verberk W.C.E.P. & Esselink H. (2003) Do restoration measures rehabilitate fauna diversity in raised bogs? A comparative study on aquatic macroinvertebrates. Wetlands Ecology and Management, 11, 447-459
At seven raised bog areas in the eastern Netherlands, to assess whether bog restoration measures contributed to conservation and restoration of the macroinvertebrate fauna, species assemblages were compared between i) water bodies created by rewetting measures and ii) water bodies not subject to restoration but remnants of former peat cuttings or trenches used for former buckwheat culture abandoned in the first half of the 20th century.
Study sites: At 47 sites in seven raised bog areas, waterbodies sampled differed in age, size, water and substrate quality, vegetation composition and structure; 27 were created by rewetting, 20 were remnants of former peat cuttings, or trenches used in buckwheat culture (50+ years old) not subject to restoration measures.
Sampling: Macroinvertebrates were sampled using a 20 × 30 cm pond net in spring 1999 and autumn 1998 or 1999, except four temporary remnant water bodies, which could only be sampled in either spring or autumn. In the laboratory, all macroinvertebrates were identified to species level if possible, except Coleoptera larvae and Oligochaetes (excluded from analysis).
Environmental variables: The year in which the restoration sites had been rewetted was ascertained. Variables assessed in summer included presence of open water, floating leaves of vascular plants, trees, muddy sediment, average Sphagnum density (capitula/dm²), and whether the water body was permanent or temporary. In spring, summer and autumn assessments included: water depth, surface area, electric conductivity and pH, and turbidity. Concentrations of various ions and elements, total inorganic carbon and oxygen content in surface water, were determined.
Classification of macroinvertebrates: Macroinvertebrates were considered characteristic of raised bogs if listed in literature as acidophilous, acidobiontic, tyrphophilous, tyrphobiontic or typical of raised bogs.
Vegetation and macroinvertebrates indices: Vegetation composition in each water body and adjacent vegetation was assessed by estimating plant species cover, each species was assigned a score based on rareness, trend and desirability from the point of view of raised bog restoration, and a vegetation quality score was calculated.
Over the 47 sites, 149 macroinvertebrate species were found, 133 were found at the 20 remnant sites versus 100 species at the 27 restoration sites; 84 were common to both.
Restoration sites were inhabited by characteristic raised bog species (including rare species) but abundance was higher at the remnant sites where a considerable number of characteristic and rare fauna species were found. The remnant sites included considerably more variation in macroinvertebrate assemblages and had a higher species richness. The number of raised bog macroinvertebrate species was not clearly related to the presence of characteristic raised bog vegetation.
In restoration sites numbers of rare and characteristic species per site tended to increase with time elapsed after rewetting.
Conclusions: In the sites sampled in this Dutch study, restoration measures had not resulted in restoration of a more or less complete macroinvertebrate species spectrum, as restoration measures had so far only recreated habitats for a limited number of species. The authors recommend safeguarding habitat diversity during the restoration process, and restoration of different elements of the habitat diversity of complete raised bog systems which may result in the characteristic fauna diversity being restored more successfully.
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