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Ecosystems are rapidly being altered and destabilized on a global scale, threatening native biota and compromising vital services provided to human society. We need to better understand the processes that can undermine ecosystem integrity (resistanceresilience) in order to devise strategies to ameliorate this trend. We used a herpetofaunal assemblage to(More)
Monitoring at large geographic scales requires a framework for understanding relationships between components and processes of an ecosystem and the human activities that affect them. We created a conceptual model that is centered on ecosystem processes, considers humans as part of ecosystems, and serves as a framework for selecting attributes for monitoring(More)
Foraging behaviour, stream habitat use and food habits of a population of the aquatic, Oregon garter snake were studied in the field during the spring and summer of 1987 and 1988. Continuous records of behaviour and habitat use were obtained for each snake. Adults foraged more actively and in a wider variety of stream habitats than juveniles or neonates.(More)
Genetic data are increasingly being used in conservation planning for declining species. We sampled both the ecological and distributional limits of the foothill yellow-legged frog, Rana boylii to characterize mitochondrial DNA (mtDNA) variation in this declining, riverine amphibian. We evaluated 1525 base pairs (bp) of cytochrome b and ND2 fragments for 77(More)
Snakes have recently been proposed as model organisms for addressing both evolutionary and ecological questions. Because of their middle position in many food webs they may be useful indicators of trophic complexity and dynamics. However, reliable data on snake populations are rare due to the challenges of sampling these patchily distributed, cryptic, and(More)
Widespread alteration of natural hydrologic patterns by large dams combined with peak demands for power and water delivery during summer months have resulted in frequent aseasonal flow pulses in rivers of western North America. Native species in these ecosystems have evolved with predictable annual flood-drought cycles; thus, their likelihood of persistence(More)
Amphibians are experiencing a precipitous global decline, and population stability on public lands with multiple uses is a key concern for managers. In the Sierra Nevada Mountains (California, USA), managers have specifically identified livestock grazing as an activity that may negatively affect Yosemite toads due to the potential overlap of grazing with(More)
--A stratified systematic sampling design was used to quantify the habitat relationships of the Del Norte salamander (Plethodon elongatus) in northwestern California. We sampled 57 sites, each within at least 5-7 ha of relatively homogeneous forest or post-forest habitat, where we measured 83 characteristics of the environment. Salamander sampling consisted(More)
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