Effects of Livestock Grazing On The Ecology Of Sierra Meadows: A Review of The Current State of Scientific Knowledge To Inform Meadow Restoration And Management.

Wet montane meadows are an important component of the Sierra Nevada, CA ecosystem that provide diverse ecological services when in functional condition. Efforts are underway to restore meadows that have been degraded from past and historic land uses. Livestock grazing is a common land use in meadows with the potential to impact Sierra meadow ecology and may be a critical determinant of restoration success. We used a systematic literature review (SLR) method to identify, review, and synthesize scientific literature about the ecological effects of livestock grazing on Sierra meadow ecology resource areas, including hydrologic function, water quality, plants, soil, fens, and fish and wildlife species. We found 47 studies that matched our search criteria for inclusion in this SLR. Livestock grazing was associated with predominantly negative effects for each resource area reviewed, suggesting that achieving functional ecological condition in Sierra meadows that are currently used for livestock grazing may be challenging. Nevertheless, there was some evidence for compatibility with certain resource areas and certain management regimes. We discuss livestock management options, ecological objectives, and research questions that emerge from the literature to help inform meadow restoration and management.

Migration tracking reveals geographic variation in the vulnerability of a Nearctic-Neotropical migrant bird.

We compared the vulnerability of a Nearctic-Neotropical migrant (Swainson's Thrush, Catharus ustulatus) for three geographically-defined breeding populations in California by linking breeding and wintering regions, estimating migration distances, and quantifying relative forest loss. Using data from light-level geolocator and GPS tags, we found that breeding birds from the relatively robust coastal population in the San Francisco Bay area wintered predominantly in western Mexico (n = 18), whereas the far rarer breeding birds from two inland populations that occur near one another in the Sierra Nevada and southern Cascades mountain ranges migrated to farther wintering destinations, with birds from the Lassen region (n = 5) predominantly going to Central America and birds from the Tahoe region (n = 7) predominantly to South America. Landscape-level relative forest loss was greater in the breeding and wintering regions of the two Cascade-Sierra populations than those of coastal birds. Longer migration distances and greater exposure to recent forest loss suggest greater current vulnerability of Cascade-Sierra birds. Our results demonstrate that for some species, quantifying migration distances and destinations across relatively small distances among breeding populations (in this case, 140-250 km apart) can identify dramatically different vulnerabilities that need to be considered in conservation planning.

A quantitative evaluation of the conservation umbrella of spotted owl management areas in the Sierra Nevada.

Whether by design or default, single species management often serves as an umbrella for species with similar habitat requirements. In recent decades the focus of National Forest management in the Sierra Nevada of California has shifted towards increasing closed canopy mature forest conditions through the protection of areas occupied by the California Spotted Owl (Strix occidentalis occidentalis). To evaluate the implications of these habitat changes and the potential umbrella resulting from a system of owl reserves on the broader avian community, we estimated occupancy of birds inside and outside of Spotted Owl Home Range Core Areas in northeastern California. We used point count data in a multi-species hierarchical Bayesian model incorporating the detection history of 81 species over a two-year time period (2005-2006). A small set of vegetation cover and topography covariates were included in the model to account for broad differences in habitat conditions, as well as a term identifying whether or not a site was within a Core Area. Seventeen species had a negative Core Area effect, seven had a positive effect, and the rest were not significant. Estimated species richness was significantly different with 23.1 species per 100 m radius circle outside Core Areas and 21.7 inside Core Areas. The majority of the species negatively associated with Core Areas are tied to early successional and other disturbance-dependent habitats. Conservation and climate vulnerability rankings were mixed. On average we found higher scores (greater risk) for the species positively associated with Core Areas, but a larger number of species with the highest scores were negatively associated with Core Areas. We discuss the implications for managing the Sierra Nevada ecosystem and illustrate the role of monitoring broader suites of species in guiding management of large complex ecosystems.