Effects of large mammal herbivory on salt marsh invertebrate communities varies with grazing type

We studied mammalian grazing (cattle, feral horses, and artificial grazing) on three barrier islands on the coast of Georgia, USA. All three grazing types altered invertebrate community composition, but in different ways. Cattle grazing had the most negative impact on plant height, chlorophyll content and toughness, and on the density and diversity of invertebrates, while artificial grazing produced some positive effects on planthoppers, herbivorous Chaetopsis spp. flies, and spiders. Although the responses to grazing of some plant traits and some invertebrate taxa were variable, plant height and katydid (Orchelimum fidicinium) density were consistently reduced by the three grazing types. Katydids did not have a feeding preference for grazed versus ungrazed plants, but grew better on ungrazed plants.