The effects of herbivory by waterfowl and nutria were measured because of vegetation loss in Sagittaria spp. dominated marshes along the coast of Louisiana. One set of study plots was set up on islands in Atchafalya Delta (fall 1985), while the other set was established on islands in Wax Lake Delta (winter 1986). Each set of plots included an exclosure that barred just nutria, one that barred just waterfowl, one that barred both, and an open grazing plot. Aboveground biomass and species composition were measured at the end of the growing season in 1986 and 1987. Belowground biomass was collected and analyzed at the same time and at the beginning of the growing season in 1987. Waterfowl were aerially counted bi-weekly during winter 1985-86 and 1986-87 and nutria were estimated via total reported trap counts from the area during 1985 and 1986.
The impact of vertebrate herbivores on wetland vegetation in Atchafalaya Bay, Louisiana