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ABSTRACT-Many coastal dune ecosystems have been degraded by non-native dune vegetation, but these systems might still provide valuable habitat for some taxa, including amphibians. Because restoration of degraded dune systems is occurring and likely to continue, we examined the occurrence of amphibians in drainages associated with a coastal dune ecosystem degraded by invasive plants (European Beachgrass, Ammophila arenaria, and Iceplant, Carpobrotus edulis). We found that occupancy of 3 amphibian species (California Red-legged Frog, Rana draytonii; Sierran Treefrog, Hyliola sierra; and Rough-skinned Newt, Taricha granulosa) among 21 coastal-dune drainages was high, with most coastal-dune drainages occupied by all 3 species. Furthermore, reproduction of Sierran Treefrogs and California Red-legged Frogs was estimated to occur in approximately / and 'A of the drainages, respectively. The probability of occurrence of Roughskinned Newts and pre-metamorphic life stages of both anurans decreased during the study, perhaps because of ongoing drought in California or precipitation-induced changes in phenology during the final year of the study. Maintaining structural cover and moist features during dune restoration will likely benefit native amphibian populations inhabiting coastal-dune ecosystems.
Key words: California Red-legged Frog, Hyliola sierra, occupancy, Point Reyes National Seashore Rana draytonii, restoration, Rough-skinned Newt, sand dunes, Sierran Treefrog, Taricha granulosa
Coastal-dune ecosystems on the western coast of the United States have been heavily invaded by non-native vegetation (Piekārt 1988). In many cases, species such as European Beachgrass (Ammophila arenaria) and Iceplant (Carpobrotus edulis) were intentionally introduced to stabilize dunes and protect human infrastructure, such as homes and roads, from shifting sands (Underwood and others 2007). Unfortunately, the plants introduced to provide this economic service often spread beyond the locations of introduction to natural areas, where they invade dune ecosystems dominated by native vegetation. These invaded dune systems have resulted in the decline of many native dune species (Piekārt 1988), including the federally endangered Tidestrom's Lupine (Lupinus tidestromii; Dangremond and others 2010) and the federally threatened Western Snowy Plover (Charadrius nivosus nivosus; Muir and Colwell 2010; Zarnetske and others 2010). In addition to effects on species of conservation concern, dunes invaded by European Beachgrass have lower diversity of arthropods than dunes dominated by native vegetation (Slobodchikoff and Doyen 1977). Because of the negative effect of invasive plants on native dune species, efforts are underway in many...