Cattle Grazing and Yosemite Toad (Bufo canorus Camp) Breeding Habitat in Sierra Nevada Meadows

Abstract

Exclusion of cattle by fencing has been proposed to alleviate possible negative grazing impacts on hydrologic, water quality, and cover habitat conditions within Sierra Nevada meadows used by Yosemite toads (Bufo canorus Camp) for breeding. Our objectives were to: 1) determine associations between breeding pool habitat conditions and use of potential breeding pools by toads; and 2) determine how habitat conditions respond to cattle exclusion treatments on the Sierra National Forest, California. We randomly selected two toad occupied and two unoccupied breeding pools in each of nine meadows for this study (n 5 36 breeding pools). After baseline data collection in 2006, three meadow fencing treatments were implemented over the course of 3 yr. Treatments were fencing to exclude cattle from the entire meadow; fencing to exclude cattle from toad breeding and rearing areas, with grazing allowed in the remaining unfenced portion of the meadow; and cattle grazing allowed across entire meadow. We monitored hydrologic, water quality, and cover habitat variables as well as toad occupancy during the breeding seasons of 2006 through 2008. Concentrations of water quality constituents were uniformly low all years regardless of treatment. Occupied pools were shallower, warmer, and more nitrogen enriched than unoccupied breeding pools. We found no evidence of improved toad breeding pool habitat conditions following fencing compared to standard US Forest Service grazing management. Resumen La exclusión del ganado por medio de cercos ha sido propuesto para reducir los posibles impactos negativos del pastoreo en la calidad del agua, la hidrología y las condiciones de cobertura del hábitat dentro de las praderas de Sierra Nevada, usados por el sapo yosemite (Bufo canorus Camp) en su reproducción. Nuestros objetivos fueron: 1) Determinar las asociaciones entre las condiciones del hábitat en un estanque de cría y el uso de estanques potenciales de cría por sapos y 2) Determinar cómo las condiciones del hábitat responden a los tratamientos de exclusión del ganado en el bosque Nacional la Sierra en California. Seleccionamos al azar dos estanques de crianza de sapos ocupados y dos sin ocupar en cada una de las nueve praderas para este estudio (n 5 36 estanques de cría). Despue´s de los valores de referencia recabados en el 2006, se implantaron tres tratamientos de cercos en praderas por un periodo de tres añ os. Los tratamientos fueron, cercar para apartar el ganado de toda la pradera, cercar para excluir el ganado de la cría del sapo y su área de reproducción, permitiendo el pastoreo en la porción restante de la pradera sin cercar y permitir el pastoreo del ganado en toda la pradera. Se monitoreo la hidrología, calidad del agua y las variables de la cobertura del hábitat, así como la ocupación del sapo durante las temporadas de reproducción del 2006 al 2008. Monitoreamos las variables de hidrología, calidad de agua y la cobertura del hábitat así como la ocupación de los sapos durante las temporadas de reproducción del 2006 al 2008. Las c...

Water Quality Conditions Associated with Cattle Grazing and Recreation on National Forest Lands

“…Our nutrient results are consistent with other examinations of surface water quality in similarly grazed landscapes. In the Sierra Nevada, Roche et al [14] found nutrient concentrations of surface waters within key cattle grazing areas (mountain meadows) to be at least an order of magnitude below levels of ecological or biological concern for sensitive amphibians. On the Wallowa-Whitman National Forest in northeastern Oregon, Adams et al [52] also reported nutrient levels to be at or below minimum detection levels in surface waters at key grazing areas.…”

“…Also in the central Sierra Nevada, Myers and Whited [13] found FIB increased in surface waters below key grazing areas on USFS allotments following the arrival of cattle. However, Roche et al [14] found no evidence of degradation of Yosemite toad breeding pool water quality in key grazing areas on three allotments in the Sierra National Forest of central California. Examining land-use and water quality associations in watersheds throughout the Cosumnes River Basin, Ahearn et al [15] also reported water quality conditions in upper forested watersheds, which include USFS grazing allotments, to be well below levels of ecological concern.…”

Elevated Stream Pathogenic Indicator Bacteria Concentrations in Livestock Grazing Areas across a Single National Forest

“…Their paper also acknowledged that up to 82% of their study's stream sites (depending on which California Region water quality standard was applied) within grazing areas had violations of fecal coliform (California standards), rather than the E. coli (federal standards) [19]. Two other studies that looked at cattle impacts to river and forest wetl and habitats concluded that cattle had minimal effects on water quality and habitat conditions; however, these studies did not actually assess fecal contamination [20] [21]. Thus, for studies that did assessfecal contamination in streams associated with livestock presence, there is consistent evidence that cattle presence is associated with diminished stream water quality.…”

Determining the Effects of Cattle Grazing Treatments on Yosemite Toads (Anaxyrus [=Bufo] canorus) in Montane Meadows

“…However, recent studies have shown that livestock grazing has either mixed effects [24] or no negative effects on amphibians [25,26]. For example, studies conducted in northeastern Oregon showed no significant effects of moderate grazing on Columbia spotted frog ( Rana luteiventris ) reproduction and short-term survival [25,27].…”

“…For example, studies conducted in northeastern Oregon showed no significant effects of moderate grazing on Columbia spotted frog ( Rana luteiventris ) reproduction and short-term survival [25,27]. A companion study to our work examined Yosemite toad response to a gradient of livestock utilization in Sierra Nevada meadows and found no direct effect of grazing on Yosemite toad presence [26]. …”