The effects of herbivory on vegetation on islands in Atchafalaya Bay, Louisiana

  • Published source details Fuller D.A., Sasser C.E., Johnson W.B. & Gosselink J.G. (1984) The effects of herbivory on vegetation on islands in Atchafalaya Bay, Louisiana. Wetlands, 4, 105-114.


This study is summarised as evidence for the following.

Action Category

Exclude wild vertebrates: freshwater marshes

Action Link
Marsh and Swamp Conservation
  1. Exclude wild vertebrates: freshwater marshes

    A replicated, controlled study in 1980–1981 in a freshwater marsh in Louisiana, USA (Fuller et al. 1985) found that plots fenced to exclude wild rodents contained more vegetation biomass than plots that remained open to grazing, but had a similar vegetation density. After both one and two growing seasons, fenced plots contained more live, above-ground vegetation biomass (242–312 g/ m2) than open plots (117–187 g/m2). The same was true for live biomass of the two most common species in the marsh: broadleaf arrowhead Sagittaria latifolia (fenced: 172; open: 106 g/m2) and valley redstem Ammania coccinea (fenced: 43; open: 10 g/m2) and for dead biomass (fenced: 281–348; open: 145–204 g/m2). However, the density of live plant stems did not significantly differ between fenced (291–396 stems/m2) and open plots (265–481 stems/m2). Methods: In March 1980, ten 1-m2 plots in a freshwater marsh were fenced (2 x 4 cm wire mesh) to exclude nutria Myocastor coypus and muskrat Ondatra zibethicus. Waterbirds could access all plots. In October 1980 and 1981, vegetation was sampled (cut, counted, dried and weighed) in each plot and 10 adjacent plots that were left open to herbivores.

    (Summarised by: Nigel Taylor)

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