Utilisation of a coastal grassland by geese after managed re-alignment

Abstract

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.