Date of Award:

5-2020

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Watershed Sciences

Advisor/Chair:

Karin M. Kettenring

Co-Advisor/Chair:

Edward W. Evans

Third Advisor:

Charles P. Hawkins

Abstract

Wetlands provide important habitat for various birds. Invasive plants can disrupt wetland food webs by altering the arthropod assemblages (invertebrate animals such as spiders, mites, insects, centipedes, and millipedes) on which these birds rely. However, differences between the wetland arthropods found in invasive vs. native vegetation are poorly defined. Wetlands are often managed for the creation of bird habitat through invasive species removal and native plant revegetation, yet few studies have examined the effects of these restoration methods on arthropod bird food sources. Phragmites australis (common reed), is an aggressive grass species in wetlands surrounding the Great Salt Lake, Utah, U.S.A. Phragmites dramatically alters the structure and composition of bird habitat by outcompeting native vegetation. While removing Phragmites can help restore bird habitat, the effects of Phragmites invasion and wetland restoration on arthropod bird food sources is unclear. Therefore, an understanding of how arthropods interact with both native vegetation and Phragmites and of arthropod assemblage changes following Phragmites removal and restoration efforts is necessary for the management of bird habitat. To address these knowledge gaps, this study identified differences in the arthropod assemblages associated with native and invasive habitats, assessed the role of restoration method in determining the arthropods found in previously-restored wetlands, and examined arthropod responses to native plant recovery following Phragmites removal. Results of this research indicated few differences between the arthropod assemblages associated with Phragmites and two native vegetation types and highlighted the importance of one native species, Salicornia rubra, which provided unique arthropod habitat. In addition, restoration method did not substantially affect the arthropods found in previously-invaded wetlands, yet Phragmites removal and native plant recovery increased arthropod abundance and activity. This research provides a framework for assessing arthropods as a food source for birds in wetlands and has several restoration implications for both the Great Salt Lake region and Phragmites-invaded wetlands across North America. By identifying the ways in which arthropods use both native and invasive vegetation and monitoring arthropods following invasive species removal and restoration, observed changes in their assemblages can offer a measure of restoration success in wetlands managed for bird habitat.

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