Small mammals in oak woodlands in the Puget Trough, Washington
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We surveyed the 22 largest sites dominated by Oregon white oaks (Quercus garryana) on the Fort Lewis Military Reservation, Washington, USA, to determine small-mammal community structure and population abundances. Study areas were in the Puget Trough physiographic province and western hemlock [Tsuga heterophylla] vegetation zone. Most oak communities were ecotonal between prairie and Douglas-fir (Pseudotsuga menziesii) forest. Small mammals were sampled at each site using paired lines of live traps for four nights, July and August 1999. In order of decreasing abundance, the deer mouse (Peromyscus maniculatus), vagrant shrew (Sorex vagrans), Trowbridge's shrew (S. trowbrdgii), and creeping vole (Microtus oregoni) were the most abundant and widespread species. The dusky shrew (S. monticolus) and the southern red-backed vole (Clethrionomys gapperi) were infrequently captured in oak ecotones but were abundant in nearby second-growth Douglas-fir forest. The relative influences of prairie versus Douglas-fir forest on oak ecotones determined understorey plant composition and occurrences of small mammal species. The combination of abundant vagrant shrews and few dusky shrews in oak ecotones suggest that soil food webs and organic matter accumulation differed between oak ecotones and Douglas-fir forest.