Some effects of grazing on vegetation dynamics in the Camargue, France

  • Published source details Bassett P.A. (1980) Some effects of grazing on vegetation dynamics in the Camargue, France. Vegetatio (now Plant Ecology), 43, 173-184.


This study is summarised as evidence for the following.

Action Category

Exclude wild vertebrates: brackish/salt marshes

Action Link
Marsh and Swamp Conservation
  1. Exclude wild vertebrates: brackish/salt marshes

    A replicated, paired, controlled study in 1975–1978 in an ephemeral brackish marsh in southern France (Bassett 1980) reported that the effects of excluding large mammalian herbivores on the dominant vegetation depended on the marsh type and which animals were excluded (horses Equus caballus and nutria Myocastor coypus, or horses only). The drier part of the marsh initially had 96–98% total vegetation cover, dominated by the grass Aeluropus littoralis (in 100% of quadrats) and alkali bulrush Scirpus maritimus (in 48–59% of quadrats). Two years later, total vegetation cover remained high in exclusion plots (full: 100%; horses: 100%) but had declined in grazed plots (83%). A. littoralis frequency had not changed in exclusion plots (full: 100%; horses: 100%) but had declined in grazed plots (79%). Alkali bulrush frequency had increased in all plots (full exclusion: 97%; horse exclusion: 88%; grazed: 96%). The wetter part of the marsh was initially dominated by alkali bulrush (in 85–93% of quadrats) and common reed Phragmites communis (in 11–27% of quadrats). Vegetation was 40–69 cm tall. After two more years, common reed frequency had increased in exclusion plots (full: 38%; horses: 64%) but decreased in grazed plots (2%). The same was true for vegetation height (full exclusion: 169 cm; horse exclusion: 116 cm; grazed: 18 cm). Alkali bulrush frequency had increased in full exclusion plots (100%), but decreased in horse exclusion plots (49%) and grazed plots (76%). Methods: In winter 1975/1976, eighteen 7 x 7 m plots were established in a brackish marsh (nine in the drier margins and nine in the wetter centre). In each part of the marsh, three plots received each treatment: full exclusion (of horses and nutria; wire fence with 3 cm mesh), partial exclusion (of horses only; fence with two barbed wire strands) and no fence (continued grazing, including <0.15 horses/ha). Vegetation was surveyed in summer 1976–1978 (frequency of each species and height of the tallest plant in fifty 15 x 15 cm quadrats/plot/year; bare ground at 100 points/plot/year).

    (Summarised by: Nigel Taylor)

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