Chang E.R.,University of Groningen |
Veeneklaas R.M.,University of Groningen |
Veeneklaas R.M.,Bosgroep Noord Oost Nederland Forest Support Group |
Bakker J.P.,University of Groningen |
And 3 more authors.
Applied Vegetation Science | Year: 2016
Questions: How successful was the restoration of a salt marsh at a former summer polder on the mainland coast of the Dutch Wadden Sea 10 yr after de-embankment? What were the most important factors determining the level of restoration success? Location: Noard-Fryslân Bûtendyks, northwest Netherlands. Methods: The frequencies of target plant species were recorded before de-embankment and monitored thereafter (1, 2, 3, 4, 6 and 10 yr later) using permanent transects. Vegetation change was monitored using repeated mapping 14 yr before and 1, 7 and 10 yr after de-embankment. A large-scale factorial experiment with 72 sampling plots was set up to determine the effects of distance to a breach point, distance to a creek and grazing treatment on species composition. Abiotic data were also collected from the permanent transects and sampling plots on elevation, soil salinity and redox potential. Results: Ten years after de-embankment, permanent transect data showed that 78% to 96% of the target species were found at the restoration site. Vegetation mapping, however, showed that the diversity of salt marsh communities was low, with 50% of the site covered by the secondary pioneer marsh community. A multivariate analogue of ANOVA indicated that the most important experimental factor determining species composition was the interaction between distance to the nearest creek and livestock grazing. The combination of proximity to a creek and exclusion from livestock grazing always resulted in development of the high marsh community. In contrast, the combination of being located far from a creek, grazed and situated at low elevation with accompanying high salinity resulted in development of the secondary pioneer marsh community. Conclusions: Using target species as criteria, restoration success could be claimed 10 yr after de-embankment. However, the diversity of communities in the salt marsh was lower than desired. Variable grazing regimes should be applied to high-elevation areas to prevent dominance by single species of tall grasses and to promote formation of vegetation mosaics. Low-elevation areas need lower grazing pressure. Also, an adequate soil drainage network should be preserved or constructed in low-elevation areas before de-embankment. © 2016 International Association for Vegetation Science. Source
Veenklaas R.M.,University of Groningen |
Veenklaas R.M.,Bosgroep Noord Oost Nederland Forest Support Group |
Koppenaal E.C.,University of Groningen |
Bakker J.P.,University of Groningen |
And 2 more authors.
Journal of Coastal Conservation | Year: 2015
Salt marshes provide an important and unique habitat for plants and animals. To restore salt marshes, numerous coastal realignment projects have been carried out, but restored marshes often show persistent ecological differences from natural marshes. We evaluate the effects of elevation and marsh topography, which are in turn affected by drainage and livestock grazing, on soil salinity after de-embankment. Salinity in the topsoil was monitored during the first 10 years after de-embankment and compared with salinity in an adjacent reference marsh. Additionally, salinity at greater depths (down to 1.2 m below the marsh surface) was monitored during the first 4 years by measuring the electrical conductivity of the groundwater. Chloride concentration in the top soil strongly decreased with increasing elevation; however, it was not affected by marsh topography, i.e. distance to creek or breach. Chloride concentrations higher than 2 g Cl−/litre were found at elevations below 0.6 m + MHT. Salinization of the groundwater, however, took several years. At low marsh elevations, the salinity of the deep groundwater (at 1.2 m depth) increased slowly throughout the full 4-year period of monitoring but did not reach the level of seawater. Compared to the ungrazed treatment, the grazed treatment led to lower accretion rates, lower soil-moisture content and higher chloride content of soil moisture. The de-embankment of the agricultural grasslands resulted in a rapid increase of soil salinity, although deeper ground-water levels showed a much slower response. Elevation accounted for most of the variation in the salinization of the soil. Grazing may enhance salinity of the top soil. © 2015 The Author(s) Source
Bos D.,Altenburg and Wymenga Ecological Consultants |
Bos D.,University of Groningen |
Boersma S.,Fryske Feriening foar Fjildbiology FFF |
Engelmoer M.,Fryske Feriening foar Fjildbiology FFF Op Dijksman |
And 5 more authors.
Journal of Coastal Conservation | Year: 2014
In this study we evaluate the effect of coastal re-alignment on the utilisation of coastal grasslands by staging geese. We assessed vegetation change and utilisation by geese using repeated mapping and regular dropping counts in both the restored marsh and adjacent reference sites. All measurements were started well before the actual re-alignment. In addition, we studied the effects of livestock grazing on vegetation and geese, using exclosures. The vegetation transformed from fresh grassland into salt-marsh vegetation. A relatively large proportion of the de-embanked area became covered with secondary pioneer vegetation, and the overall cover of potential food plants for geese declined. Goose utilisation had initially dropped to low levels, both in autumn and in spring, but it recovered to a level comparable to the reference marsh after ten years. Exclosure experiments revealed that livestock grazing prevented the establishment of closed swards of grass in the poorly drained lower area of the restored marsh, and thereby negatively affected goose utilisation of these areas during spring staging. Goose grazing in the restored marsh during spring showed a positive numerical response to grass cover found during the preceding growing season. (1) The value of restored salt marsh as foraging habitat for geese initially decreased after managed re-alignment but recovered after ten years. (2) Our findings support the idea that the value of foraging habitats depends largely on the cover of forage plants and that this can be manipulated by adjusting both grazing and drainage. © 2014 Springer Science+Business Media Dordrecht. Source