Effects of grazing by feral horses, clipping, trampling, and burning on a Georgia salt marsh
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- Turner, M.G. Estuaries (1987) 10: 54. doi:10.2307/1352025
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Responses ofSpartina alterniflora marsh to combinations of feral horse grazing, clipping, simulated trampling, and a late winter burn were studied on Cumberland Island National Seashore, Georgia. Replicated 200-m2 plots were established and sampled bimonthly from July 1983 to November 1984. Clipping and trampling each reduced peak aboveground biomass by 20% in 1983 and 50% (clipping) and 55% (trampling) in 1984. A March burn reduced peak aboveground biomass by 35% in 1984. Trampling and burning earch reduced net aboveground primary production (NAPP) by 35%, but clipping did not reduce NAPP. Standing stocks of live rhizomes were correlated with aboveground biomass and were reduced with experimental treatments. Abundance of the periwinkle snail (Littorina irrorata) was also reduced. Horse grazing had a substantial impact on standing stocks and NAPP ofSpartina, but grazing was not uniform throughout the marsh. Moderately grazed plots had NAPP reduced by 25% compared to ungrazed plots. Heavily grazed plots had extremely low NAPP, and abovegroundSpartina never exceeded 40 g m−2 dry mass compared to 360 g m−2 within exclosures.