Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “The Mountaineer”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
USGS2001

Oral chytridiomycosis in the mountain yellow-legged frog (Rana muscosa)

The chytrid fungus Batrachochytrium dendrobatidis was originally reported in wild frog populations in Panama and Australia, and from captive frogs in the U.S. National Zoological Park (Washington, DC). This recently described fungus affects the keratinized epidermis of amphibians and has been implicated as a causative factor in the declines of frog populations. We report here the presence of B. dendrobatidis in larval and recently metamorphosed mountain yellow-legged frogs ( Rana muscosa ) in or near the Sierra Nevada Mountains of California, an area where declines have been documented in all five species of native anurans. Forty-one percent (158 of 387) of larval R. muscosa examined in the field with a hand lens and 18% (14 of 79) of preserved larvae had abnormalities of the oral disc. Twenty-eight larvae were collected from 10 sites where tadpoles had been observed with missing or abnormally keratinized mouthparts, and 24 of these were examined for infection. Sixty-seven percent (16 of 24) of these tadpoles were infected with B. dendrobatidis. Batrachochytrium dendrobatidis was cultured from both tadpoles and recent metamorphs from one of these sites. Tadpoles with mouthpart abnormalities or confirmed chytrid fungus infections were collected at 23 sites spanning a distance of > 440 km and an elevational range from 1658-3550 m. Life-history traits of R. muscosa may make this species particularly susceptible to infection by Batrachochytrium . We recommend that biologists examine tadpoles for oral disc abnormalities as a preliminary indication of chytridiomycosis. Further, we believe that biologists should take precautions to prevent spreading this and other amphibian diseases from one site to another.

California↗
USGS2016

Avian response to fire in pine–oak forests of Great Smoky Mountains National Park following decades of fire suppression

Fire suppression in southern Appalachian pine–oak forests during the past century dramatically altered the bird community. Fire return intervals decreased, resulting in local extirpation or population declines of many bird species adapted to post-fire plant communities. Within Great Smoky Mountains National Park, declines have been strongest for birds inhabiting xeric pine–oak forests that depend on frequent fire. The buildup of fuels after decades of fire suppression led to changes in the 1996 Great Smoky Mountains Fire Management Plan. Although fire return intervals remain well below historic levels, management changes have helped increase the amount of fire within the park over the past 20 years, providing an opportunity to study patterns of fire severity, time since burn, and bird occurrence. We combined avian point counts in burned and unburned areas with remote sensing indices of fire severity to infer temporal changes in bird occurrence for up to 28 years following fire. Using hierarchical linear models that account for the possibility of a species presence at a site when no individuals are detected, we developed occurrence models for 24 species: 13 occurred more frequently in burned areas, 2 occurred less frequently, and 9 showed no significant difference between burned and unburned areas. Within burned areas, the top models for each species included fire severity, time since burn, or both, suggesting that fire influenced patterns of species occurrence for all 24 species. Our findings suggest that no single fire management strategy will suit all species. To capture peak occupancy for the entire bird community within xeric pine–oak forests, at least 3 fire regimes may be necessary; one applying frequent low severity fire, another using infrequent low severity fire, and a third using infrequently applied high severity fire.

The Condor↗
USGS2018

Habitat associations of three crayfish endemic to the Ouachita Mountain Ecoregion

Many crayfish are of conservation concern because of their use of unique habitats and often narrow ranges. In this study, we determined fine-scale habitat use by 3 crayfishes that are endemic to the Ouachita Mountains, in Oklahoma and Arkansas. We sampled Faxonius menae (Mena Crayfish), F. leptogonopodus (Little River Creek Crayfish), and Fallicambarus tenuis (Ouachita Mountain Crayfish) from wet and dry erosional channel units of 29 reaches within the Little River catchment. We compared channel-unit and microhabitat selection for each species. Crayfish of all species and life stages selected erosional channel units more often than depositional units, even though these sites were often dry. Accordingly, crayfish at all life stages typically selected the shallowest available microhabitats. Adult crayfish of all species and juvenile Little River Creek Crayfish selected patches of coarse substrate, and all crayfish tended to use the lowest amount of bedrock available. In general, we showed that these endemic crayfish used erosional channel units of streams, even when the channel units were dry. Conservation efforts that protect erosional channel units and mitigate actions that cause channel downcutting to bedrock would benefit these crayfish, particularly during harsh, summer drying periods.

Oklahoma↗
USGS2016

New permian fusulinids from conglomerate mesa, southeastern inyo Mountains, east-central california

In the Conglomerate Mesa area in the southeastern Inyo Mountains, east-central California, a series of distinctive fusulinid assemblages ranging in age from late Artinskian to Kungurian or Roadian was developed in units 7-10 of the sedimentary rocks of Santa Rosa Flat (part of the Owens Valley Group). The fauna of unit 7 shows some eastern Klamath Mountains affinity, but most of the species in unit 7 and the lower half of unit 8 are highly endemic and comprise three new genera with 12 new species, two unusual unassigned forms, and two other new species assigned to previously described genera. New taxa include: Crenulosepta new genus with five new species, C. inyoensis, C. delicata, C. fusiformis, C. rossi, and C. wahlmani; Nigribaccinus new genus with three new species, N. giganteus, N. elegans, and N. ? nestelli; and the new genus Inyoschwagerina with four new species, I. magnified, I. elayeri, I. elongata, and I.? linderae. Cuniculinella Skinner and Wilde, 1965, is represented by one new species, C. parva, and Skinnerella Coogan, 1960 by one new species, S.? mcallisteri. Faunas from the upper half of unit 8, unit 9, and unit 10 have a strong West Texas affinity. New species from these units are Skinnerella davydovi, S. hexagona, Parafusulina cerrogordoensis, P. complexa, P. halli, P. owensensis, and P. ubehebensis. Copyright ?? 2009, The Paleontological Society.

Journal of Paleontology↗
USGS2012

Red-tailed Hawk movements and use of habitat in the Luquillo Mountains of Puerto Rico

The Red-tailed Hawk ( Buteo jamaicensis ) is a top predator of upland ecosystems in the Greater Antilles. Little information exists on the ecology of the insular forms of this widely distributed species. We studied movements and resource use of the Red-tailed Hawk from 2000 to 2002 in the montane forests of northeastern Puerto Rico. We captured 32 and used 21 radio-marked Red-tailed Hawks to delineate home range, core area shifts, and macrohabitat use in the Luquillo Mountains. Red-tailed Hawks in the Luquillo Mountains frequently perched near the top of canopy emergent trees and were characterized by wide-ranging capabilities and extensive spatial overlap. Home range size averaged 5,022.6 ± 832.1 ha (305–11,288 ha) and core areas averaged 564.8 ± 90.7 ha (150–1,230 ha). This species had large mean weekly movements (3,286.2 ± 348.5 m) and a preference for roadside habitats. Our findings suggest fragmentation of contiguous forest outside protected areas in Puerto Rico may benefit the Red-tailed Hawk.

Puerto Rico↗
USGS2020

Breeding biology of the Mountain Wren-Babbler (Gypsophila crassus)

Life history theory in ornithology has been mostly based on temperate birds in part because a relative paucity of biological data has been described for tropical species. Expanding our knowledge about life histories of tropical birds can help us to better understand global trends in life history strategies. To aid in this endeavor, we studied Mountain Wren-Babblers ( Gypsophila crassus ) breeding in Malaysian Borneo from 2009 to 2017. Relatively small (mean = 28.8 g), dark brown birds, they were cooperative breeders and foraged and cared for the nest in groups of typically 4 or 5 birds. We located 145 nests, which were globular and partially domed (91.8 mm mean opening height accounted for half of 180.7 mm total mean nest height), constructed from fern fronds on the outside and dead leaves on the inside, and most often placed on banks. Brooding attentiveness decreased with nestling age and was rare after day 7 once they began growing their primary feathers. Provisioning rate slightly increased with nestling age. Nestling growth rate constants were typical of many tropical birds, asymptoting a few days prior to fledging. Predation accounted for nearly all nest failures (87 of 88), with a daily nest predation rate for the total nesting period of 0.056 and nest success decreasing with elevation. Daily predation rate was highest during lay (0.117) and lowest during incubation (0.046). We compared these results with related species to identify potential explanations for the trends we described. The most notable result from these comparisons was that Mountain Wren-Babblers have a long incubation period (23.5 d) and adults only incubate for a small part of the day. This anomalous behavior emphasizes the importance of understanding the great variation in tropical life history strategies to ultimately improve life history theory.

Mount Kinabalu↗
USGS2002

Evidence for two surface ruptures in the past 500 years on the San Andreas fault at Frazier Mountain, California

We conducted paleoseismic studies in a closed depression along the San Andreas fault on the north flank of Frazier Mountain near Frazier Park, California. We recognized two earthquake ruptures in our trench exposure and interpreted the most recent rupture, event 1, to represent the historical 1857 earthquake. We also exposed evidence of an earlier surface rupture, event 2, along an older group of faults that did not rerupture during event 1. Radiocarbon dating of the stratigraphy above and below the earlier event constrains its probable age to between A.D. 1460 and 1600. Because we documented continuous, unfaulted stratigraphy between the earlier event horizon and the youngest event horizon in the portion of the fault zone exposed, we infer event 2 to be the penultimate event. We observed no direct evidence of an 1812 earthquake in our exposures. However, we cannot preclude the presence of this event at our site due to limited age control in the upper part of the section and the possibility of other fault strands beyond the limits of our exposures. Based on overlapping age ranges, event 2 at Frazier Mountain may correlate with event B at the Bidart fan site in the Carrizo Plain to the northwest and events V and W4 at Pallett Creek and Wrightwood, respectively, to the southeast. If the events recognized at these multiple sites resulted from the same surface rupture, then it appears that the San Andreas fault has repeatedly failed in large ruptures similar in extent to 1857.

California↗
USGS2005

Coal-mining seismicity and ground-shaking hazard: A case study in the Trail Mountain area, Emery County, Utah

We describe a multipart study to quantify the potential ground-shaking hazard to Joes Valley Dam, a 58-m-high earthfill dam, posed by mining-induced seismicity (MIS) from future underground coal mining, which could approach as close as ???1 km to the dam. To characterize future MIS close to the dam, we studied MIS located ???3-7 km from the dam at the Trail Mountain coal mine. A 12-station local seismic network (11 stations above ground, one below, combining eight triaxial accelerometers and varied velocity sensors) was operated in the Trail Mountain area from late 2000 through mid-2001 for the dual purpose of (1) continuously monitoring and locating MIS associated with longwall mining at a depth of 0.5-0.6 km and (2) recording high-quality data to develop ground-motion prediction equations for the shallow MIS. (Ground-motion attenuation relationships and moment-tensor results are reported in companion articles.) Utilizing a data set of 1913 earthquakes (M ??? 2.2), we describe space-time-magnitude distributions of the observed MIS and source-mechanism information. The MIS was highly correlated with mining activity both in space and time. Most of the better-located events have depths constrained within ??0.6 km of mine level. For the preponderance (98%) of the 1913 located events, only dilatational P-wave first motions were observed, consistent with other evidence for implosive or collapse-type mechanisms associated with coal mining in this region. We assess a probable maximum magnitude of M 3.9 (84th percentile of a cumulative distribution) for potential MIS close to Joes Valley Dam based on both the worldwide and regional record of coal-mining-related MIS and the local geology and future mining scenarios.

Bulletin of the Seismological Society of America↗
USGS2005

Development of ground-motion prediction equations relevant to shallow-mining-induced seismicity in the Trial Mountain area, Emery County, Utah

To provide a basis for assessing the seismic hazard to the Joes Valley Dam due to future coal mining in the nearby Cottonwood Tract, central Utah, we developed ground-motion prediction relations using data recorded by a seismic network, established and operated by the University of Utah Seismograph Stations. The network was centered on the Trail Mountain coal mine, located adjacent to the Cottonwood Tract. From late 2000 until early 2001, this network recorded numerous mining-induced events with magnitudes as large as 2.17. The ground motion from these events, recorded at hypocentral distances ranging from about 500 m to approximately 10 km, were well suited to developing new ground-motion prediction relations, especially when augmented by data from a M 4.2 earthquake in the Willow Creek mine, about 50 km north of Trail Mountain. Using a two-stage regression analysis, we determined prediction relations for peak acceleration, peak velocity, and pseudovelocity response spectra, at 5% damping, for periods of 0.1, 0.2, 0.5, 1.0, and 2.0 s. To illustrate the potential seismic hazard at the Joes Valley dam, we used these ground-motion relations to predict a peak velocity of 6.8 cm/s due to an earthquake with the probable maximum magnitude of 3.9, at a hypocentral distance of 1 km, recorded at a rock site typical for this region. This result does not take into account the site response at the dam.

Bulletin of the Seismological Society of America↗
USGS2020

Teleseismic P‐qave coda autocorrelation imaging of crustal and basin structure, Bighorn Mountains Region, Wyoming, U.S.A.

We demonstrate successful crustal imaging via teleseismic P ‐wave coda autocorrelation, using data recorded on a 261 station array of vertical‐component high‐frequency geophones in the area of the Bighorn Mountains, Wyoming, U.S.A. We autocorrelate the P ‐wave coda of 30 teleseismic events and use phase‐weighted stacking to yield seismic profiles comparable to low‐passed versions of those produced via controlled‐source vertical seismic reflection. Our process recovers reflections from the bottoms of the Bighorn and Powder River basins that flank the Bighorn Mountains. We also identify a mid‐crustal reflector that aligns with a region of increased reflectivity, previously interpreted as a Precambrian province boundary. Our results demonstrate the utility of crustal imaging with teleseismic P ‐wave coda energy using modern large‐array seismic data, and they corroborate previous interpretations of crustal structures in the study area.

Wyoming↗
USGS2020

Holocene paleoseismology of the Steamboat Mountain Site: Evidence for full‐Llngth rupture of the Teton Fault, Wyoming

The 72‐km‐long Teton fault in northwestern Wyoming is an ideal candidate for reconstructing the lateral extent of surface‐rupturing earthquakes and testing models of normal‐fault segmentation. To explore the history of earthquakes on the northern Teton fault, we hand‐excavated two trenches at the Steamboat Mountain site, where the east‐dipping Teton fault has vertically displaced west‐sloping alluvial‐fan surfaces. The trenches exposed glaciofluvial, alluvial‐fan, and scarp‐derived colluvial sediments and stratigraphic and structural evidence of two surface‐rupturing earthquakes (SM1 and SM2). A Bayesian geochronologic model for the site includes three optically stimulated luminescence ages ( ⁠ ∼ 12 – 17 ka ⁠ ) for the glaciofluvial units and 16 radiocarbon ages ( ⁠ ∼ 1.2 – 8.6 ka ⁠ ) for the alluvial‐fan and colluvial units and constrains SM1 and SM2 to 5.5 ± 0.2 ka , 1 σ (5.2–5.9 ka, 95%) and 9.7 ± 0.9 ka , 1 σ (8.5–11.5 ka, 95%), respectively. Structural, stratigraphic, and geomorphic relations yield vertical displacements for SM1 ( ⁠ 2.0 ± 0.6 m , 1 σ ⁠ ) and SM2 ( ⁠ 2.0 ± 1.0 m , 1 σ ⁠ ). The Steamboat Mountain paleoseismic chronology overlaps temporally with earthquakes interpreted from previous terrestrial and lacustrine paleoseismic data along the fault. Integrating these data, we infer that the youngest Teton fault rupture occurred at ∼ 5.3 ka ⁠ , generated 1.7 ± 1.0 m , 1 σ of vertical displacement along 51–70 km of the fault, and had a moment magnitude ( ⁠ M w ⁠ ) of ∼ 7.0 – 7.2 ⁠ . This rupture was apparently unimpeded by structural complexities along the Teton fault. The integrated chronology permits a previous full‐length rupture at ∼ 10 ka and possible partial ruptures of the fault at ∼ 8 – 9 ka ⁠ . To reconcile conflicting terrestrial and lacustrine paleoseismic data, we propose a hypothesis of alternating full‐ and partial‐length ruptures of the Teton fault, including M w ∼ 6.5 – 7.2 earthquakes every ∼ 1.2 ky ⁠ . Additional paleoseismic data for the northern and central sections of the fault would serve to test this bimodal rupture hypothesis.

Wyoming↗
USGS2007

Disruptions of stream sediment size and stability by lakes in mountain watersheds: Potential effects on periphyton biomass

The location of a stream reach relative to other landforms in a watershed is an important attribute. We hypothesized that lakes disrupt the frequency of finer, more mobile sediments and thereby change sediment transport processes such that benthic substrates are more stable (i.e., less mobile) below lakes than above lakes. In turn, we hypothesized that this reduced mobility would lead to greater periphyton biomass below lakes. We tested these hypotheses in study reaches above and below lakes in 3 mountain watersheds. To expand this comparison, we analyzed the relationship between sediment attributes and periphyton biomass in one watershed with and one watershed without a lake. We hypothesized that no clear pattern or change in sediment size or chlorophyll a (chl a) would be observed over a 3-km-long study reach without a lake. In contrast, we expected a clear discontinuity in both sediment size and chl a in a 7-km-long study reach interrupted by a lake. Average median sediment size (D50) was significantly larger (p < 0.01) in lake-outlet than lake-inlet reaches (41 mm vs 10 mm). Bed sediments in lake-outlet reaches were immobile during bankfull flows, whereas sediments at lake-inlet reaches were mobile during bankfull flows. Chlorophyll a was ???10x greater in lake-outlet reaches than in lake-inlet reaches, although this difference was not statistically significant (p = 0.17). The longitudinal analysis clearly showed geomorphic transitions in sediment size and mobility downstream of mountain lakes, and these geomorphic transitions might be associated with changes in periphyton biomass. Geomorphic transitions can alter sediment transport and should be considered in concert with other factors that are considered more commonly in benthic ecology, such as light, nutrients, and temperature. ?? 2007 by The North American Benthological Society.

Journal of the North American Benthological Societ↗
USGS1943

Quartz veins in the Ouachita mountains of Arkansas and Oklahoma (Their relations to structure, metamorphism, and metalliferous deposits)?

An important chapter of the total geologic history of the Ouachita Mountains is revealed by the quartz veins and crystals. These and the associated minerals are hydrothermal deposits of probable magmatic origin, formed during the closing stage of the mid-Permsylvanian orogeny. The metalliferous deposits of the Ouachita Mountains appear to have been formed at the time of the quartz vein deposition. This /act should be considered in dating the lead and zinc mineralization in other areas of the Mississippi Valley region. © 1943 Society of Economic Geologists, Inc.

Arkansas, Oklahoma↗
USGS1989

Geologic setting, depths of emplacement, and regional distribution of fluid inclusions in intrusions of the central Wasatch Mountains, Utah

Nine mid-Tertiary calc-alkaline stocks, a subvolcanic porphyry system, and coeval volcanic rocks are exposed in a 45-km-long east-trending belt across the central Wasatch Mountains, Utah. The intrusions vary systematically from west to east in texture, style of emplacement, extent of contact metamorphism, hydrothermal alteration, and mineralization. Pressure-depth estimates based on metamorphic mineral assemblages, stratigraphic reconstructions, and fluid inclusion data indicate a regular variation in paleodepths ranging from about 11 km on the west to less than 1 km on the east. These data indicate that the central Wasatch Mountains have been tilted down to the east about 20 degrees during the late Cenozoic. Fluid inclusion populations in igneous quartz also vary systematically with paleodepth; high-salinity (halite-saturated) fluid inclusions are present in the eastern porphyry stocks and in the upper parts of the Alta and Clayton Peak stocks in the center of the belt but are absent in the deeper parts of the Alta and Clayton Peak stocks and in the Little Cottonwood stock on the west side of the belt. In the Alta and Clayton Peak stocks, nearly planar high-paleosalinity horizons, presently dipping 15 degrees to 20 degrees east, separate rocks containing high-salinity fluid inclusions (above the high-paleosalinity horizon) from those lacking such fluid inclusions. Comparison of fluid-inclusion populations in igneous and vein quartz in the Alta and Clayton Peak stocks indicates that high-salinity fluids predated most of the vein-forming hydrothermal activity and provide the earliest record of fluids to circulate in these stocks. High-salinity fluids probably formed either by boiling of fluids released during the late stages of crystallization in the parts of the intrusions where pressure was less than about 1,300 bars or by exsolution of immiscible high-salinity brines from the crystallizing magmas. Most hydrothermal mineralization associated with the intrusions, including Ag-Pb-Zn ores in the Park City district, are associated spatially with parts of the intrusions where high-salinity fluids were present. The major exception is the porphyry molybdenum system in the eastern part of the Little Cottonwood stock, which probably was at too great a depth (approximately 7 km) to form high-salinity brines and is dominated by low-salinity CO 2 -rich fluids.

Economic Geology↗
USGS2016

The road to Yucca Mountain—Evolution of nuclear waste disposal in the United States

The generation of electricity by nuclear power and the manufacturing of atomic weapons have created a large amount of spent nuclear fuel and high-level radioactive waste. There is a world-wide consensus that the best way to protect mankind and the environment is to dispose of this waste in a deep geologic repository. Initial efforts focused on salt as the best medium for disposal, but the heat generated by the radioactive waste led many earth scientists to examine other rock types. In 1976, the director of the U.S. Geological Survey (USGS) wrote to the U.S. Energy Research and Development Administration (ERDA), predecessor agency of the U.S. Department of Energy (DOE), suggesting that there were several favorable environments at the Nevada Test Site (NTS), and that the USGS already had extensive background information on the NTS. Later, in a series of communications and one publication, the USGS espoused the favorability of the thick unsaturated zone. After the passage of the Nuclear Waste Policy Act (1982), the DOE compiled a list of nine favorable sites and settled on three to be characterized. In 1987, as the costs of characterizing three sites ballooned, Congress amended the Nuclear Waste Policy Act directing the DOE to focus only on Yucca Mountain in Nevada, with the proviso that if anything unfavorable was discovered, work would stop immediately. The U.S. DOE, the U.S. DOE national laboratories, and the USGS developed more than 100 detailed plans to study various earth-science aspects of Yucca Mountain and the surrounding area, as well as materials studies and engineering projects needed for a mined geologic repository. The work, which cost more than 10 billion dollars and required hundreds of man-years of work, culminated in a license application submitted to the U.S. Nuclear Regulatory Commission (NRC) in 2008.

Environmental & Engineering Geoscience↗
USGS1993

Atmospheric transport of organophosphate pesticides from California's Central Valley to the Sierra Nevada Mountains

Atmospheric transport of organophosphate pesticides from California's Central Valley to the Sierra Nevada mountains was assessed by collecting air- and wet-deposition samples during December, January, February, and March, 1990 to 1991. Large-scale spraying of these pesticides occurs during December and January to control insect infestations in valley orchards. Sampling sites were placed at 114- (base of the foothills), 533-, and 1920-m elevations. Samples acquired at these sites contained chlorpyrifos [phosphorothioic acid; 0,0-diethyl 0-(3,5,6-trichloro-2-pyridinyl) ester], parathion [phosphorothioic acid, 0-0-diethylo-(4-nitrophenyl) ester], diazinon {phosphorothioic acid, 0,0-diethyl 0-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] ester} diazinonoxon {phosphoric acid, 0,0-diethyl 0-[6-methyl-2-(1-methylethyl)-4-pyrimidinyl] ester}, and paraoxon [phosphoric acid, 0,0-diethyl 0-(4-nitrophenyl) ester] in both air and wet deposition samples. Air concentrations of chloropyrifos, diazinon and parathion ranged from 13 to 13 000 pg/m 3 at the base of the foothills. At 533-m air concentrations were below the limit of quantification (1.4 pg/m 3 ) to 83 pg/m 3 and at 1920 m concentrations were below the limit of quantification. Concentrations in wet deposition varied with distance and elevation from the Central Valley. Rainwater concentrations at the base of the foot hills ranged from 16 to 7600 pg/mL. At 533-m rain and snow water concentrations ranged from below the limit of quantification (1.3 pg/mL) to 140 pg/mL and at 1920 m concentrations ranged from below the limit of quantification to 48 pg/mL. These findings indicate that atmospheric transport of pesticides applied in the valley to the Sierra Nevada mountains is occurring, but the levels decrease as distance and elevation increase from the valley floor.

Journal of Environmental Quality↗
USGS2000

Carbon distribution in subalpine forests and meadows of the Olympic Mountains, Washington

stimates of C storage in mountainous regions are rare. Forest–meadow ecotones in subalpine ecosystems, which contain a mosaic of forests and meadows, may be particularly sensitive to future changes in climate and are therefore important to include in estimates of terrestrial C storage. In this study, we quantified soil C and ecosystem C pools in subalpine forest and meadow soils of the northeastern (NE, dry climate) and southwestern (SW, wet climate) Olympic Mountains. Carbon concentrations of mineral soil are relatively high in upper horizons, ranging from 43 to 142 g kg −1 in NE soils and 27 to 162 g kg −1 in SW soils. Northeastern meadow soils store more C than NE forests ( P = 0.009) , while SW forest soils store more C than SW meadows ( P = 0.038) Ecosystem C storage is greater in forests than in meadows. Under a warmer climatic scenario with drier summers and wetter winters, subalpine C storage may decrease in the NE and increase in the SW, and changes in C storage will be closely related to vegetation distribution, ecosystem productivity, decomposition rates, and local disturbance regimes. Because ecosystem processes and associated C storage differ between high- and low-elevation ecosystems, it is important that data from both high- and low-elevation sites are included in estimates of C storage in terrestrial ecosystems.

Soil Science Society of America Journal↗
USGS2005

Mountain plover population responses to black-tailed prairie dogs in Montana

We studied a local population of mountain plovers (Charadrius montanus) in southern Phillips County, Montana, USA, from 1995 to 2000 to estimate annual rates of recruitment rate (f) and population change (??). We used Pradel models, and we modeled ?? as a constant across years, as a linear time trend, as year-specific, and with an additive effect of area occupied by prairie dogs (Cynomys ludovicianus). We modeled recruitment rate (f) as a function of area occupied by prairie dogs with the remaining model structure identical to the best model used to estimate ??. Our results indicated a strong negative effect of area occupied by prairie dogs on both ?? (slope coefficient on a log scale was -0.11; 95% CI was -0.17, -0.05) and f (slope coefficient on a logit scale was -0.23; 95% CI was -0.36, -0.10). We also found good evidence for a negative time trend on ??; this model had substantial weight (wi = 0.31), and the slope coefficient on the linear trend on a log scale was -0.10 (95% CI was -0.15, -0.05). Yearly estimates of ?? were >1 in all years except 1999, indicating that the population initially increased and then stabilized in the last year of the study. We found weak evidence for year-specific estimates of ??; the best model with year-specific estimates had a low weight (wi = 0.02), although the pattern of yearly estimates of ?? closely matched those estimated with a linear time trend. In southern Phillips County, the population trend of mountain plovers closely matched the trend in the area occupied by black-tailed prairie dogs. Black-tailed prairie dogs declined sharply in the mid-1990s in response to an outbreak of sylvatic plague, but their numbers have steadily increased since 1996 in concert with increases in plovers. The results of this study (1) increase our understanding of the dynamics of this population and how they relate to the area occupied by prairie dogs, and (2) will be useful for planning plover conservation in a prairie dog ecosystem.

Journal of Wildlife Management↗