Species Diversity Changes and Habitat Associations of Small Mammals at Ash Meadows National Wildlife Refuge, Nye County, Nevada
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Ash Meadows National Wildlife Refuge (Ash Meadows NWR), a spring-fed wetlands and alkaline desert system located in the Mojave Desert in Nye County, Nevada, supports 25 species of endemic plants and animals (5 currently listed as federally endangered). Human activities have caused scale habitat alterations to the land and biotic communities of Ash Meadows NWR through peat-mining and spring diversions for irrigation purposes. Restoration projects are currently being developed because of the endangered endemic species. My objectives were to determine changes in small mammal diversity over time and identify habitat types and vegetative characteristics inhabited by small mammals. Information on small mammal specimens collected for two surveys in 1891 and 1933 was used to assess species diversity changes over time. Small mammal trap lines were set in 18 qualitatively different habitat types during 6 sampling seasons (2 each in spring, summer, and fall) in 2008–2009. Habitat characteristics were quantified for each habitat type then joined to individual small mammal traps in ArcMap 9.3. A two-factor MANOVA (multivariate analysis of variance) was conducted to test for differences in habitat variables between habitat types and a single-factor MANOVA for differences between capture and non-capture sites. A CCA (canonical correspondence analysis) was conducted to assess small mammal habitat associations. Species diversity in 1891 was similar to the results of my study; however, diversity in 1933was not similar. Habitats differed in structural components seasonally as well as between capture and non-capture trap sites mostly because of the unique seeps and springs system present. Small mammals were primarily associated with shrub dominated and graminoid dominated habitat associations. Overall, shrub and graminoid dominated habitats are important for small mammal communities; however, other habitat types are equally important in sustaining biodiversity at Ash Meadows NWR.