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Title Grazers vs Grazers: Large Mammal Herbivores Influence Salt Marsh Invertebrate Communities
Archive All Files / Documents / Publications / Theses - Dissertations
Abstract

Large mammals cause disturbances in the environments in which they graze by dramaticallychanging the physical structure of habitats. The response of plant and animal communities tomegafaunal herbivory is highly variable among ecosystems, geographic location, and species ofinterest. Past research has often only focused on the response of a single taxa, and effects ofgrazing in North American salt marshes is understudied. I conducted field studies on threebarrier islands on the coast of Georgia, USA. Each island served as a site for one of three grazingtreatments (cattle, feral horses, and artificial grazing by clipping). Treatment and control plotsat the three sites were sampled for vegetation metrics and invertebrate abundance anddiversity. All three grazing types altered invertebrate community composition, and eachrepresented a different level of grazing intensity. Cattle grazing had a particularly negativeimpact, while artificial grazing produced some opposite effects. Some vegetation characteristicsand taxa had varied responses, but others responded similarly to all three grazing types. Plantheight and katydid density were consistently reduced by the three grazing types, indicating thatgrazed vegetation does not provide katydids with ideal conditions. To further investigate this, Iperformed two katydid feeding experiments and found that a more nutritious diet may notnecessarily be more palatable. The responses of different taxonomic groups and invertebratecommunities and the underlying mechanisms should be considered when making livestock andland management decisions that aim to promote ecosystem functioning.

Contributor Kori Lugar
Citation

Lugar, K. 2022. Grazers vs Grazers: Large Mammal Herbivores Influence Salt Marsh Invertebrate Communities. M.S. Thesis. University of Houston, Houston.

Key Words cattle, herbivory, horses, insects, megafauna
File Date 2022
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NSF

This material is based upon work supported by the National Science Foundation under grants OCE-9982133, OCE-0620959, OCE-1237140 and OCE-1832178. Any opinions, findings, conclusions, or recommendations expressed in the material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.