Secondary succession on a high salt marsh at different grazing intensities |
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Authors: | M Kleyer H Feddersen R Bockholt |
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Institution: | (1) Landscape Ecology Group, University of Oldenburg, PO Box 2503, D-26111 Oldenburg, Germany;(2) Feldstr. 1, D-91054 Erlangen, Germany;(3) Fachgebiet Grünland und Futterbau, University of Rostock, Justus-von-Liebig-Weg 6, D-18059 Rostock, Germany |
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Abstract: | Succession occurs on a large part of German salt marshes following abandonment or reduction of grazing. Its speed and effect
on the biodiversity of salt marshes has been discussed in the literature. Permanent plot studies show site-dependent differences
in successional outcome. If grazing is to be continued, there is uncertainty about the stocking rates that are optimal for
the conservation of plant diversity. We present an eight year permanent plot study with different grazing treatments on a
high salt marsh at the marsh island of Hallig Langeness, Germany, which is enclosed by a summer dike. The study site is owned
by WWF. Successional outcomes on the permanent plots depend on grazing intensity and depth of the groundwater table which
is correlated with soil salinity. Intermediate stocking rates support a mixture of halophytes and glycophytes, the relative
proportion of which depends on the depth of the groundwater table. Cattle grazing at stocking rates of 0.6 livestock units
per ha were found to be optimal for plant diversity conservation. At sites with deeper groundwater tables and no grazing,
dominantElymus spp. stands develop and diversity is strongly reduced. If the groundwater table is high, succession following grazing abandonment
is retarded and small halophytes prevail. |
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Keywords: | Competition Conservation Grazing effect Groundwater table Langeness Permanent plot Salinity |
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