Ardea
Official journal of the Netherlands Ornithologists' Union

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Vulink J.T., van Eerden M.R. & Drent R.H. (2010) Abundance of migratory and wintering geese in relation to vegetation succession in man-made wetlands: the effects of grazing regimes. ARDEA 98 (3): 319-327
The man-made wetlands in young polders in the Netherlands are important stopover and wintering sites for geese. We studied trends in vegetation composition and goose density in two study areas. One was located in a nature reserve situated in a polder reclaimed from an estuary, the other in a reserve in a polder reclaimed from a freshwater lake. In the former we compared an area of spontaneous vegetation succession with a summer- grazed area. In the latter the effect of reed Phragmites australis cover and height on field selection of geese was studied in an area grazed year-round by cattle and horses. In both study areas the area of short grassland (reed cover about 1%, reed height <0.5 m) was found to be significantly positively related to the grazing density of cattle and horses. Migrating and wintering Greylag Geese Anser anser and Barnacle Geese Branta leucopsis preferred to feed on these extensive short grassland. In the ungrazed part of the study site in the reclaimed estuarine area, there was an inverse relation between goose density and the ousting of pioneer species of saline habitats and short grasses by tall species such as Calamagrostis epigejos, Phragmites australis, tall herbs and shrubs. Summer grazing by cattle and horses at stocking rates of about 0.4 to 0.9 animals/ha, retarded the vegetation succession to some extent, which resulted in a goose density being higher in the summer-grazed area than in the ungrazed area. The implications for management are that the more desalinated the area becomes and the higher its clay content, the higher the stocking rate must be to retard the vegetation succession.


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