Kern Plateau Research Articles

Using discordant U-Pb zircon data to re-evaluate the El Paso terrane: Late Paleozoic tectonomagmatic evolution of east-central California (USA) and intense hydrothermal activity in the Jurassic Sierra Nevada arc

AbstractQuantitative modeling of discordant detrital zircon U-Pb isotope data from the northern El Paso terrane reveals metamorphosed Laurentian passive-margin strata within the Kern Plateau (southeastern Sierra Nevada), resolving a 40-year-long debate regarding this terrane’s origin. Previous studies of Kern Plateau pendants identify deep-water metasediments containing detrital zir-con populations similar to the Roberts Mountains allochthon; yet structural observations seemingly contradict proposed correlations to the Mississippian Roberts Mountains thrust, which juxtaposes exotic deep-water rocks over shallow-water, passive-margin strata in central Nevada. Here, new samples are combined with published data to identify segments of the thrust within the Kern Plateau, demonstrating that the El Paso terrane was offset ~350 km by late Paleozoic sinistral translation along the braided Kern Plateau shear zone, an abandoned model first proposed more than 20 years ago.New U-Pb-Hf isotope data from plutons intruding the Kern Plateau shear zone are virtually identical to published data from the El Paso Mountains, indicating that the Sierra Nevada–Mojave arc initiated in the late Early Permian (ca. 274 Ma) along the entire length of the El Paso terrane and was active into the Middle Triassic (ca. 240 Ma). Previously implicated Late Triassic arc activity within the Kern Plateau is not corroborated by single-crystal U-Pb data. Published structural evidence indicating reactivation of the late Paleozoic Kern Plateau shear zone is reinterpreted as indicating sinistral-oblique relative plate motion during Permian arc initiation followed by Middle Jurassic extension in the southeastern Sierra Nevada arc, which facilitated intense hydrothermal activity and zircon lead loss.

Habitat and drought influence the diet of an unexpected mycophagist: fishers in the Sierra Nevada, California

AbstractClimate change is creating hotter, drier, and more extreme weather. Weather anomalies such as extended drought along the Pacific Coast of North America are redefining ecosystems. In the Sierra Nevada mountains of California, an isolated, distinct and federally endangered population of fishers (Pekania pennanti) currently faces multiple threats. Severe drought, tree mortality, and megafires are reshaping the landscape in the southern Sierra with largely unknown effects on fisher ecology and conservation. Using hair collected during long-term population monitoring, we analyzed stable isotopes to quantify the diets of fishers before and after drought, and explored how habitat quality mediated the effect of drought on fisher diet. For the core population of fishers which occupy the northern and western portions of this region, their isotopic niche declined both in drought and in lower-quality habitats. Regardless of drought or habitat conditions, the summer diet of fishers here was dominated by fungi (47%), while little vertebrate mass (14%) was consumed. However, drought and habitat did influence consumption of plants and insects; fishers consumed more insects and less plants in drought conditions and in poorer habitat. In contrast, at the perennially dry, high-altitude Kern Plateau at the southeastern extent of their range, fishers predominantly consumed vertebrates (59%). Fishers show great plasticity in their diet, but the means and capacity for this flexibility is poorly understood. Retaining atypical diet items, notably fungi, and a diversity of forage in the Sierra Nevada could help to buffer the negative fitness costs from rapid environmental change for this endangered species.

Use of higher severity fire areas by female Pacific fishers on the Kern Plateau, Sierra Nevada, California, USA

ABSTRACTThe Pacific fisher (Pekania pennanti) is a rare and imperiled forest carnivore, with a genetically distinct and isolated population living in the southern Sierra Nevada mountains of California, USA. Female fishers are of special interest and concern, given their very small numbers and their disproportionately important role in the potential recovery of the population. Using fisher scat detection to assess patterns of habitat use, I conducted analyses regarding use by fishers of unlogged higher severity fire areas at 10–11 years postfire in the 2002 McNally fire area. Contrary to the prevailing current hypothesis regarding fisher postfire habitat use, fishers did not use higher severity fire areas less than low–moderate‐severity areas or unburned forest (n = 77 scats), and female fishers used the large, intense McNally fire area significantly more than unburned forest (n = 12 scats). Female fishers were detected at multiple locations >250 m into the interior of a very large (>5,000 ha), unlogged higher severity fire patch. These results indicate unlogged higher severity fire areas are suitable habitat for fishers, especially female fishers, and suggest a need to revisit current management direction, which emphasizes extensive commercial thinning and postfire logging to reduce fuels and control fire. © 2015 The Wildlife Society.

Habitat Use of Pacific Fishers in a Heterogeneous Post-Fire and Unburned Forest Landscape on the Kern Plateau, Sierra Nevada, California

The Pacific fisher (Martes pennanti) is a rare forest carnivore strongly associated with dense, old forest with high canopy cover for denning and resting. The Sierra Nevada population is very small, genetically distinct, and isolated. Mixed-severity wildland fire is assumed to be a potentially greater threat than logging, and land managers are conducting large-scale forest thinning operations under the hypothesis that it is needed to reduce fire spread and severity. However, the relationship between fishers and fire has not been tested previously. I investigated this question with teams of dogs specially trained to detect the scat of Pacific fishers and, thus, their concentration of movements and habitat use. All scat samples were genetically verified. In surveys on the Kern Plateau in the southwestern Sierra Nevada, within unlogged post-fire forests with mixed-severity effects from large fires, and in unburned forests, I found that fishers selected Sierran mixed-conifer forests in both post-fire and unburned areas, and selected closed-canopied, mature/old forest in unburned forests, as well as burned forests that had this structure in the pre-fire condition. When fishers were near burned/unburned edges, they selected the within-fire side. Fishers used dense, mature/old forest that experienced moderate/high-severity fire at the same level as unburned dense, mature/old forest, and both males and females were found deep inside large fires—several km from the fire perimeter. These results indicate that fishers may benefit from the structural complexity of such post-fire habitat for foraging. This suggests mixed-severity wildland fire could be restored through managed wildland fire in these forests.

Effects of young Artemisia rothrockii shrubs on soil moisture, soil nitrogen cycling, and resident herbs

AbstractQuestions: How do young sagebrush shrubs (Artemisia rothrockii, Asteraceae) affect soil moisture availability? How do young sagebrush shrubs affect soil nitrogen cycling? How does the resident herb community respond to shrub removal in the early stages of sagebrush encroachment?Location: Mulkey and Bullfrog Meadows on the Kern Plateau in the Golden Trout Wilderness, Sierra Nevada Mountains, Inyo National Forest, Inyo County, California, USA.Methods: We removed young encroaching sagebrush shrubs from 3.5 m × 3.5 m plots and compared soil moisture, net mineralization, net nitrification, and herb cover with paired control plots over four growing seasons.Results: On average throughout the experiment, the difference between removal plots and control plots in soil moisture was small. Removal plots were wetter by 1.3 ± 2.0% at 0–30 cm depth, 2.1 ± 3.1% at 30–60 cm depth and 3.1 ± 5.8% at 60–90 cm depth. By contrast, after four years, net mineralization was 32 ± 26% (mean ± 95% CI) lower in sagebrush removal plots, suggesting that sagebrush encroachment increases rates of N‐cycling. Total herb cover was 13.0 ± 6.4% (mean ± 95% CI) higher in plots where young sagebrush shrubs were removed. This difference in cover appeared during the first season in which sagebrush shrubs were removed.Conclusions: Our results suggest that while young sagebrush shrubs do not contribute substantially to meadow drying, they alter N cycling rates, and may indirectly increase the rate of their own encroachment by competitively reducing resident herbs.

Statistical Clustering of Major Solutes: Use as a Tracer for Evaluating Interbasin Groundwater Flow into Indian Wells Valley, California

Many previous studies have demonstrated use of specific solutes or isotopes as tracers of groundwater flow. We present a technique that uses standard hydrochemical information to create statistically based hydrochemical facies, which are then used as tracers of groundwater flow.This approach reduces potential subjective bias during interpretation of single tracer data in complex systems with multiple sources or conflicting multiple tracer data. Standard hydrochemical data from 1,368 water samples that spanned more than 80 years were analyzed using cluster analysis to decipher groundwater flow paths in Indian Wells Valley (IWV), California. The statistically derived hydrochemical facies form distinct spatial patterns in which all major-ion concentrations increase progressively from Sierra Nevada (recharge) to China Lake playa (discharge), consistent with the topographically driven flow of groundwater (the typical case for basin and range flow systems). However, once individual samples could be placed in the context of the normal hydrochemical evolution, anomalies are readily identifiable. The distribution of water chemistry in the southeastern part of the IWV does not conform to the regional trend. Groundwater from that part of the IWV is statistically more similar to waters from the Kern Plateau area (in the high Sierra Nevada outside the local watershed) than to waters from the local watershed. The groundwater is interpreted to originate from the fracture-directed interbasin flow from the Kern Plateau area that is directly recharging the alluvial aquifer in the subsurface. Inclusion of this flow could substantially alter current water budgets and water resources management approaches.

New Species of Slender Salamander, Genus Batrachoseps, from the Southern Sierra Nevada of California

Populations of robust salamanders belonging to the plethodontid salamander genus Batrachoseps (subgenus Plethopsis) from the southern Sierra Nevada and adjacent regions represent a previously unknown species here described as Batrachoseps robustus. The new species is robust, with a short trunk (17‐18 trunk vertebrae) and well-developed limbs. It differs from its close geographic neighbor, Batrachoseps campi, in lacking patches of dorsal silvery iridophores and in having (typically) a lightly pigmented dorsal stripe, and from Batrachoseps wrighti in being more robust, having more trunk vertebrae, and in lacking conspicuous white spots ventrally. This species is widely distributed on the semiarid Kern Plateau of the southeastern Sierra Nevada and extends along the east slopes of the mountains into the lower Owens Valley; it also is found to the south in the isolated Scodie Mountains. It occurs at high elevations, from 1615‐2800 m, in areas of low rainfall and high summer temperatures.

Mediterranean climate effects. I. Conifer water use across a Sierra Nevada ecotone

Xylem water potential of the midelevation conifers Pinus jeffreyi, Pinus lambertiana, Abies concolor, and Calocedrus decurrens, the higher elevation Pinus monticola and Abies magnifica, and co-occurring evergreen angiosperm shrubs, together with soil moisture under these plants, were monitored at three sites on the Kern Plateau in the southernmost Sierra Nevada Range of California. Site locations spanned the ecotone between the mid- and upper montane forests at elevations of 2230-2820 m. Measurements were made through a low-snowfall year and a heavy-snowfall year.In the Mediterranean climate of the Sierra Nevada, the heavy winter snowpack persists into late spring, after precipitation has effectively stopped. We found the subsequent depletion of soil moisture due to plant water uptake to result in predawn xylem water potentials for conifers more negative by 0.6-1.4 MPa than those for shrubs or inferred soil potentials. Shrubs generally depleted soil moisture more rapidly and ultimately extracted a greater fraction of the available soil moisture than did the conifers. This depletion of soil moisture by shrubs, particularly Arctostaphylos patula, may limit conifer growth and regeneration by prematurely terminating growth on the shallow soils studied. The conifers all generally showed similar patterns of soil moisture use, except that A. magnifica extracted moisture more rapidly early in the season.

Palynological evidence for 19th century grazing-induced vegetation change in the southern Sierra Nevada, California, U.S.A.

Summary Aim Stratigraphic pollen records are used to assess historic vegetation changes that have transpired in a North American mountain meadow since the introduction of Old World livestock species in the middle 1800s. Location Monache Meadows is located on the Kern Plateau in the Sierra Nevada mountain range, California, U.S.A. It is situated along the upper reaches of the South Fork Kern River in the southernmost drainage basin of the Sierra Nevada. Methods Short core samples of meadow sediments were extracted from five locations throughout Monache Meadows. These five samples are classified according to topographic position within the meadow – two upper meadow sites and three lower meadow sites. Stratigraphic analyses of fossil pollen from each core were used to assess vegetation composition before the introduction of European livestock (pre1850) and throughout the historic period (1850–present). The historic period geochronology is based on 210Pb dating of selected strata from each core. ResultsRiccia was a dominant taxon in the upper meadow before the introduction of grazing; Salix seems to have been more abundant in the lower meadow. Both Riccia and Salix decreased dramatically by c.1900, coeval with marked increases in Artemisia (upper meadow) and Cyperaceae (upper and lower meadows). Main conclusions Changes in meadow vegetation occurring during the latter part of the 19th century at Monache Meadows are attributed primarily to the introduction of European livestock (sheep and cattle). Other factors that may have contributed to the observed shifts in composition and dominance include changes in native herbivore populations and decreased fire frequency as a result of 20th century fire suppression policies.

Abstract: The Kern Plateau: A Potential Extra-basinal Source of Groundwater Recharge to the Indian Wells Valley

Abstract: The Kern Plateau: A Potential Extra-basinal Source of Groundwater Recharge to the Indian Wells Valley

Nolina cismontana (Nolinaceae), a New Species Name for an Old Taxon

Nolina parryi subsp. wolflii is shown to be a synonym of N. parryi subsp. parryi. Consequently, N. parryi subsp. parryi sensu Munz has been misinterpreted and is without a name. Nolina cismontana is proposed as the name for this undescribed taxon. It is necessary to publish a new name for Nolina parryi S. Watson sensu Munz before volume 11 of the Flora of North America is published. The junior author studied the California Nolina species complex for his M.S. thesis (Dice, 1988). He determined that the name N. parryi was assigned by western botanists to the wrong plants, and consequently these plants are unnamed. Munz (in Munz & Roos, 1950) described Nolina parryi subsp. wolfi based on plants from the Kingston Range in the eastern Mojave Desert and the San Jacinto/Santa Rosa Mountains along the northwestern edge of the Colorado Desert. Plants fitting this description are now known to extend from the Kern Plateau in southern Tulare County south to the Laguna and Pinyon Mountains of San Diego County, California. The taxon is found in the drier parts of the Peninsular Ranges, along the western edge of the Colorado Desert and in the desert ranges of the Mojave Desert. This means that by this interpretation subspecies parryi occurs in the coastal drainages below 3000 feet from Ventura to San Diego counties and west of subspecies wolfii. There is no evidence that Munz ever examined the type of N. parryi. Dice examined the holotypes and isotypes of subspecies parryi and subspecies wolfii. The holotype of subspecies parryi and Watson's (1879) publication of its description indicate that N. parryi came from the desert east of San Bernardino and not from the coastal side of the mountains. The leaves on this holotype and isotype are wider than what Munz allows for his subspecies parryi and would key out in his keys to subspecies wolfii. Subspecies wolfi is a synonym for Watson's typical N. parryi, and the plants from the coastal drainages that Munz was calling subspecies parryi are without

Late Cenozoic rhyolites from the Kern Plateau, southern Sierra Nevada, California

Late Cenozoic rhyolites from the Kern Plateau, southern Sierra Nevada, California

Developing a cost-effective fire management plan for California's Kern Plateau

The Kern Plateau in Sequoia National Forest was selected as a pilot study area for the development and application of a new fire management planning process.