Study

The effects of vertebrate herbivory on plant community structure in the coastal marshes of the Pearl River, Louisiana, USA

  • Published source details Taylor K.L. & Grace J.B. (1995) The effects of vertebrate herbivory on plant community structure in the coastal marshes of the Pearl River, Louisiana, USA. Wetlands, 15, 68-73.

Actions

This study is summarised as evidence for the following.

Action Category

Exclude wild vertebrates: freshwater marshes

Action Link
Marsh and Swamp Conservation

Exclude wild vertebrates: brackish/salt marshes

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

    A replicated, randomized, paired, controlled study in 1991 in a freshwater marsh in Louisiana, USA (Taylor & Grace 1995) reported that plots fenced to exclude nutria Myocastor coypus contained more overall vegetation biomass than plots that remained open to grazing, but had similar plant species richness. Statistical significance was not assessed. After two growing seasons, above-ground vegetation biomass was 1,600 g/m2 in fenced plots, compared to 1,270 g/m2 in open plots. However, fenced and open plots contained a statistically similar biomass of the dominant plant species: switchgrass Panicum virgatum (fenced: 771; open: 517 g/m2) and big cordgrass Spartina cynosuroides (fenced: 381; open: 355 g/m2). Fenced plots contained 12.3 plant species/m2, compared to 12.7 plant species/m2 in open plots. Methods: In March 1990, twelve 4-m2 plots were established (in three sets of four) in a freshwater marsh. Six of the plots (two random plots/set) were fenced (2.5 cm plastic-coated mesh) to exclude nutria (and other large mammals). The other six plots were left open. In September 1991, all vegetation was cut from one 1-m2 quadrat/plot. Plant species were identified, then the vegetation was dried and weighed. This study was in the same area as (4), but used a different experimental set-up.

    (Summarised by: Nigel Taylor)

  2. Exclude wild vertebrates: brackish/salt marshes

    A replicated, randomized, paired, controlled study in 1991 in two brackish marshes in Louisiana, USA (Taylor & Grace 1995) reported that plots fenced to exclude nutria Myocastor coypus contained more overall vegetation biomass than plots that remained open to grazing, but had similar plant species richness. Statistical significance was not assessed. After two growing seasons, above-ground vegetation biomass was 990–1,150 g/m2 in fenced plots, compared to 720–910 g/m2 in open plots. However, fenced and open plots contained a statistically similar biomass of the dominant plant species: saltmeadow cordgrass Spartina patens (fenced: 501; open: 290 g/m2) and smooth cordgrass Spartina alterniflora (fenced: 993; open: 713 g/m2). Fenced and open plots had similar plant species richness: 10.3–10.4 species/m2 in one marsh and 1.5–2.0 species/m2 in the other. Methods: In March 1990, twenty-four 4-m2 plots were established (in six sets of four) across two brackish marshes. Twelve of the plots (two random plots/set) were fenced (2.5 cm plastic-coated mesh) to exclude nutria (and other large mammals). The other 12 plots were left open. In September 1991, all vegetation was cut from one 1-m2 quadrat/plot. Plant species were identified, then the vegetation was dried and weighed. This study was in the same area as (5), but used a different experimental set-up.

    (Summarised by: Nigel Taylor)

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