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At least 1,387 records · Page 77Linked to original sources
USGS2018

A landscape-level assessment of whitebark pine regeneration in the Rocky Mountains, USA

Whitebark pine (Pinus albicaulis Engelm.) has recently experienced high mortality due to multiple stressors, and future population viability may rely on natural regeneration. We assessed whitebark pine seedling densities throughout the US Rocky Mountains and identified stand, site, and climatic variables related to seedling presence based on data from 1,217 USDA Forest Service Forest Inventory and Analysis plots. Although mean densities were highest in the whitebark pine forest type, 83% of sites with seedlings present occurred in non-whitebark pine forest types, and the highest densities occurred in the lodgepole pine forest type. To identify factors related to whitebark pine seedling presence, we compared the results generated from three statistical models: logistic regression, classification tree, and random forests. All three models identified cover of grouse whortleberry (Vaccinium scoparium Leiberg ex Coville) as an important predictor, two models distinguished live and dead whitebark pine basal area and elevation, and one model recognized seasonal temperature. None of the models identified forest type as an important predictor. Understanding these factors may help managers identify areas where natural regeneration of whitebark pine is likely to occur, including sites in non-whitebark pine forest types.

Rocky Mountains↗
USGS2024

Evidence of extensive home range sharing among mother–daughter bobcat pairs in the wildland–urban interface of the Tucson Mountains

Urbanization impacts the structure and viability of wildlife populations. Some habitat generalists, such as bobcats ( Lynx rufus ), maintain populations at the intersection of wild and urban habitats (wildland urban interface, WUI), but impacts of urbanization on bobcat social structure are not well understood. Although commonly thought to establish exclusive home ranges among females, instances of mother-daughter home range sharing have been documented. We combined GPS localities with genomic relatedness inferences from double-digest restriction site associated DNA sequencing (ddRADseq) to investigate mother-daughter home range sharing in bobcats ( n = 38) at the WUI in the Tucson Mountains, Arizona, USA. We found the highest relatedness among females, which showed stronger isolation by distance than males and the population as a whole. Using mother-daughter relationships inferred from pedigree reconstruction, we found extensive mother-daughter home range sharing, compared to other females. Every mother identified as having at least one daughter, shared home ranges with one daughter, while other confirmed daughters established adjacent home ranges. Our results provide substantial support for the mother-daughter home range sharing hypothesis, as well as evidence of spatiotemporal overlap between mothers and daughters, adding to the body of research complicating the solitary felid paradigm. These results additionally challenge the notion of home range partitioning by prior rights land tenure, suggesting a role of matrilineal land tenure in home range establishment of daughters. Habitat fragmentation due to human population growth and urbanization thus has the potential to alter landscape genetic structure and social dynamics in bobcats.

Arizona↗
USGS2016

Ecology, distribution, and predictive occurrence modeling of Palmers chipmunk ( Tamias palmeri ): a high-elevation small mammal endemic to the Spring Mountains in southern Nevada, USA

Although montane sky islands surrounded by desert scrub and shrub steppe comprise a large part of the biological diversity of the Basin and Range Province of southwestern North America, comprehensive ecological and population demographic studies for high-elevation small mammals within these areas are rare. Here, we examine the ecology and population parameters of the Palmer’s chipmunk ( Tamias palmeri ) in the Spring Mountains of southern Nevada, and present a predictive GIS-based distribution and probability of occurrence model at both home range and geographic spatial scales. Logistic regression analyses and Akaike Information Criterion model selection found variables of forest type, slope, and distance to water sources as predictive of chipmunk occurrence at the geographic scale. At the home range scale, increasing population density, decreasing overstory canopy cover, and decreasing understory canopy cover contributed to increased survival rates.

Nevada↗
USGS1995

Sources of the Early Cretaceous plutons in the Turtle and West Riverside Mountains, California

Ages and initial isotopic ratios of Early Cretaceous (˜100 Ma) plutons of the Cordilleran Interior in the southern Turtle and West Riverside mountains distinguish them from Late Cretaceous plutons in surrounding ranges in the eastern Mojave Desert. Furthermore, the studied plutons have isotopic and geochemical characteristics more similar to plutons of Cretaceous age in the coastal batholiths (Peninsular Ranges and Sierra Nevada) than to most Mesozoic plutons in the Cordilleran Interior. The studied plutons are calcic, in contrast to the mostly cak-alkaline Mesozoic plutons of the eastern Mojave Desert. Distinctive isotopic signatures of the granitoids include lower initial 87 Sr/ 86 Sr of 0⋅705–0⋅710, δ 18 O of +6⋅3 to +7⋅7‰, 208 Pb/ 204 Pb of 38⋅3–39⋅5, and higher ε Nd of −3⋅86 to −9⋅60 than the Late Cretaceous plutons in the region. The distinctive characteristics of these Early Cretaceous plutons are probably both location and time specific and result from: (1) emplacement in a cold, untapped ‘Mojave-type’ Proterozoic upper crust, (2) a significant component of basaltic magmas partially melted from the asthenosphere or subcontinental lithosphere and (3) a magmatic component derived from Proterozoic, mafic, lower crust. They interacted less with their crustal hosts than did the later, more voluminous Late Cretaceous plutons.

California↗
USGS1971

Structure and petrology of the alpine-type peridotite at Burro Mountain, California, U.S.A.

The alpine-type peridotite at Burro Mountain is a partially serpentinized harzburgite-dunite body approximately 2 km in diameter. It lies in a chaotic mélange derived from the Franciscan Formation (Upper Jurassic to Upper Cretaceous) of the southern Coast Ranges of California. The peridotite is bounded on the east by a vertical fault in the Nacimiento fault zone that brings sedimentary rocks of Taliaferro's (1943 b ) Asuncion Group (Upper Cretaceous) into contact with the peridotite. The peridotite appears to be one of a number of tectonic lenses, having a wide range in size, that make up the mélange . These lenses include metagraywacke, metachert, greenstone, amphibolite, and blueschist, as well as ultramafic rocks, and represent a wide range of pressure-temperature environments. The outer shell of the peridotite is a sheared serpentinite zone 10–15 m thick. The peridotite was tectonically emplaced at its present level as a cold solid mass and had little effect on the mineral assemblages of the Franciscan Formation. Local development of lawsonite and aragonite in shear zones may be related to the peridotite emplacement. Foliated harzburgite forms approximately 60 per cent of the peridotite. It is a lithologically uniform rock that has an olivine: orthopyroxene ratio of approximately 75:25. Accessory clinopyroxene and chromian spinel generally make up less than 5 per cent of the harzburgite. Dunite, composed of olivine, accessory chromian spinel (< 5 per cent), and trace amounts of pyroxene, makes up approximately 40 per cent of the peridotite and occurs as dikes, sills, and irregular bodies in the harzburgite. Olivine and pyroxene show small but significant compositional variations and chromian spinel shows a large range in the cation ratio Cr/(Cr+Al+ Fe 3+ ). The compositional variations in these minerals are related to original differences in bulk chemical composition. The following compositional ranges were determined for minerals in the harzburgite: olivine, Fo 91.1 −Fo 91.4 ; orthopyroxene, En 89.8 −En 91.1 ; clinopyroxene, Ca 47.0 Mg 50.0 Fe 3.0 −Ca 48.7 Mg 48.2 Fe 3.1 ; chromian spinel, Cr/(Cr+Al+Fe 3+ ) 0.37−0.55. The pyroxenes have a range in A1 2 O 3 content of 1.3−3.0 wt per cent. Olivine from dunite ranges from Fo 91 to Fo 92 7 and the chromian spinel has a range in the Cr/(Cr+Al+Fe 3+ ) ratio of 0.30−0.75. Although all the dunites are lithologically similar, three distinct types are recognized on the basis of composition of coexisting olivine and chromian spinel. Structural relations between the three types of dunite suggest three periods of emplacement (possibly overlapping) of dunite into harzburgite. The evidence indicates that the dunite, and probably also the harzburgite crystallized from an ultramafic magma, probably in the upper mantle. After the magmatic episode and crystallization, the peridotite was subjected to a deep-seated plastic deformation and recrystallization. The first phase of the deformation produced a pervasive, planar structural element (S 1 ) that crosscuts many harzburgite-dunite contacts. It is probable that some of the dunite sills were emplaced during this deformation. The foliation, S 1 , is defined by layers of different orthopyroxene content in harzburgite, and by discontinuous layers of chromian spinel in dunite. Flow or slip along S 1 produced slip folds in harzburgite—dunite contacts with axial planes parallel to S 1 . At a later stage, isoclinal folds developed in S 1 , and the present olivine microfabric was probably formed by recrystallization in the stress field that produced the isoclinal folding. In the olivine microfabric, X tends to be perpendicular to the axial planes (S 2 ) of the isoclinal folds and Y and Z tend to form double maxima in S 2 approximately 90° apart. Mg−Fe 2+ distribution between coexisting mineral pairs yields a calculated temperature of formation of approximately 1200 °C. Although this temperature is only a nominal value, it indicates that the mineral pairs equilibrated at a significantly high temperature. In view of the deformation and recrystallization, the calculated temperature possibly represents subsolidus re-equilibration of the minerals during this event. The deformation and recrystallization probably occurred shortly after crystallization while the peridotite was still at a high temperature. A later deep-seated deformation produced small scattered kink folds in S 1 that tend to disrupt the major olivine microfabric. The kink folding was accompanied or followed by the development of kink bands in olivine that reflect intragranular gliding on the system T = [ Okl ], t = [100]. The kink bands probably formed at a minimum temperature of 1000 °C. Following the deep-seated deformation, which probably took place in the mantle, the peridotite mass was tectonically detached and moved upward to its present level in the crust. Cleavages, joints, and faults provided channels for water to pervade the peridotite and allow alteration of the primary minerals.

California↗
USGS1990

Geochemistry and intrusive history of the Ashland pluton, Klamath Mountains, California and Oregon

The Ashland pluton is a calc-alkaline plutonic complex that intruded the western Paleozoic and Triassic belt of the Klamath Mountains in late Middle Jurassic time. The pluton comprises a series of compositionally distinct magma pulses. The oldest rocks are hornblende gabbro and two-pyroxene quartz gabbro with initial 87 Sr/ 86 Sr = 0˙7044, δ 18 O = 8˙7%, and REE patterns with chondrite normalized La/Lu = 7. These units were followed by a suite of tonalitic rocks (La N /Lu N = 7) and then by a suite of K 2 O- and P 2 O 5 rocks of quartz monzodioritic affinity (La N /Lu N = 13–21; La N /Sm N = 2˙4–3˙) The quartz monzodioritic rocks were then intruded by biotite granodiorite and granite with lower REE abundances but more fractionated LREE(La N /Lu N = 13–19; La N /Sm N = 4˙3–6 and they, in turn, were host to dikes and bosses of hornblende diorite. The latest intrusive activity consisted of aplitic and granitic dikes. Combined phase equilibria and mineral composition data, indicate emplacement conditions of approximately P total = 2˙3kb, P H2O between 1˙5 and 2˙2 kb, and f O2 between the nickel-nickel oxide and hematite-magnetite buffers. Successive pulses of magma display increasing SiO 2 together with increasing δ 18 O and decreasing initial 87 Sr/ 86 Sr. The isotopic data are consistent with either (1) combined fractional crystallization of andesitic magma and concurrent assimilation of crustal material characterized by low Sr 1 and high (δ 18 O or, more probably, (2) a series of partial melting events in which sources were successively less radiogenic but richer in 18 O Each intrusive stage displays evidence for some degree of crystal accumulation and/or fractional crystallization but neither process adequately accounts for their compositional differences. Consequently, each stage appears to represent a distinct partial melting or assimilation event. The P 2 O 5 -rich nature of the quartz monzodiorite suite suggests accumulation of apatite. However, the suite contains abundant mafic microgranitoid enclaves and most apatite in the suite is acicular. These observations suggest that magma mixing affected the compositional variation of the quartz monzodiorite suite. Mass balance calculations are consistent with a simple mixing process in which P 2 O 5 -rich alkalic basalt magma (represented by the mafic microgranitoid enclaves) was combined with a crystal-poor felsic magma (represented by the tonalite suite), yielding a quartz monzodioritic magma that then underwent differentiation by crystal fractionation and accumulation.

California, Oregon↗
USGS1995

Effects of hydrology on zooplankton communities in high-mountain ponds, Mount Rainier National Park, USA

Ten high-mountain ponds in Mount Rainier National Park, Washington State, were studied from ice-out in June through September1992 to investigate the influences of fluctuating pond volumes on zooplankton communities. All of the ponds were at maximum volume immediately after ice-out. The temporary pond with the shortest wet phase was inhabited by rotifer taxa with short generation times and a crustacean taxon with the ability to encyst as drought-resistant resting bodies at immature stages of development. Dominant zooplankton taxa in three other temporary ponds and six permanent ponds were similar. Rotifer densities typically were lower in temporary ponds relative to those in permanent ponds, although Brachionus urceolaris was abundant shortly before the temporary ponds dried. Large volume loss was associated with large declines in total abundances of crustacean populations. Daphnia rosea was not present in temporary ponds following fall recharge. In deep-permanent ponds, copepods had slower developmental rates, smaller temporal changes in total abundances of crustacean populations and two additional large-bodied crustacean taxa were present relative to the characteristics of crustacean communities in shallow-permanent ponds. Owing to their small sizes and sensitivity to environmental change, collectively ponds such as these may provide an early signal of long-term climate change in aquatic systems.

Journal of Plankton Research↗
USGS2020

Nutrients and warming interact to force mountain lakes into unprecedented ecological state

While deposition of reactive nitrogen (N) in the 20th century has been strongly linked to changes in diatom assemblages in high-elevation lakes, pronounced and contemporaneous changes in other algal groups suggest additional drivers. We explored the origin and magnitude of changes in two mountain lakes from the end of the Little Ice Age at ca. 1850, to ca. 2010, using lake sediments. We found dramatic changes in algal community abundance and composition. While diatoms remain the most abundant photosynthetic organisms, concentrations of diatom pigments decreased while pigments representing chlorophytes increased 200-300% since ca. 1950 and total algal biomass more than doubled. Some algal changes began ca. 1900, but shifts in most sedimentary proxies accelerated ca. 1950 commensurate with many human-caused changes to the Earth system. In addition to N deposition, aeolian dust deposition may have contributed phosphorus. Strong increases in summer air and surface water temperatures since 1983 have direct and indirect consequences for high elevation ecosystems. Such warming could have directly enhanced nutrient use and primary production. Indirect consequences of warming include enhanced leaching of nutrients from geologic and cryosphere sources, particularly as glaciers ablate. While we infer causal mechanisms, changes in primary producer communities appear to be without historical precedent and are commensurate with the post-1950 acceleration of global change.

Proceedings of the Royal Society B: Biological Sci↗
USGS2021

Mineral Mapping of the Battle Mountain District, Nevada, USA, Using AVIRIS-Classic and SpecTIR Inc. AisaFENIX 1K Imaging Spectrometer Datasets

Imaging spectroscopy (hyperspectral imaging) has been used to successfully map minerals at the outcrop, deposit, district, and regional scale. This contribution presents spectral-based mineral maps of the Battle Mountain mining district, Nevada, USA, generated using multi-scale airborne imaging and ground-based point spectrometers. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and AisaFENIX 1K imaging spectrometer data were processed using Atmospheric and Topographic Correction (ATCOR-4) software with an empirical correction multiplier derived from field data. Data were used to generate spectral-based mineral maps with spatial resolutions of 13.5 and 1.8 m. A comparison of the various radiative transfer models used to convert radiance data to reflectance indicated that the ATCOR4 rugged model performed best for these datasets. These mineral maps were then used to spectrally characterize two potential porphyry mineral targets in the district.

Nevada↗
USGS2026

Depositional interplay between the Ancestral Rocky Mountains and Ouachita–Marathon–Sonora orogenies: Insights from provenance records in the late Paleozoic Marfa Basin, West Texas, U.S.A.

The Marfa Basin in West Texas is a late Palaeozoic synorogenic depocenter associated with regional deformation linked to the Ancestral Rocky Mountains (ARM) and Ouachita–Marathon–Sonora (OMS) orogenies in southwestern Laurentia. Basin strata range in age from Middle Pennsylvanian to the middle Permian and include the Cieneguita, Alta, Pinto Canyon, Rose Mine and Mina Grande Formations. Sandstone petrography and detrital zircon (DZ) U–Pb and (U–Th)/He double dating data from these strata reveal three tectonically driven sedimentation stages: syntectonic ARM deposition, progressive OMS foredeep deposition and an orogenic transition. The Cieneguita and lower part of the Alta Formations exhibit a Mesoproterozoic DZ age signature (~1318 and ~1076 Ma age peaks) and quartzo-feldspathic sandstone compositions sourced from the adjacent ARM-related Diablo Platform basement uplift in the Middle Pennsylvanian to earliest Permian. In contrast, the upper part of the Alta Formation, as well as the Pinto Canyon and Rose Mine Formations, have peri-Gondwanan DZ age signatures, with Mesoproterozoic (~1069–1036 Ma age peaks), Neoproterozoic–Cambrian (~700–490 Ma) and Palaeozoic (~490–300 Ma) age modes and litho-quartzose sandstone compositions derived from the OMS fold-and-thrust belt and orogenic hinterland during the early to middle Permian. The lower to middle parts of the Alta Formation have alternating DZ age signatures and sandstone compositions from both ARM and OMS sources, revealing that the transition in the sediment supply occurred during the middle Wolfcampian. This transition was not characterised by source mixing, but rather by sediment interfingering alternately sourced from the Diablo Platform uplift and the advancing OMS belt. These observations are confirmed by the DZ He ages, which reveal distinct cooling histories for both source terranes. These results document a switch from ARM- to OMS-related syntectonic deposition in southwestern Laurentia during the early Permian, demonstrating that ARM-driven deformation largely preceded the continental collision along the Marathon segment of the OMS orogen.

Texas↗
USGS2022

Defining relevant conservation targets for the endangered Southern California distinct population segment of the mountain yellow-legged frog (Rana muscosa)

The endangered mountain yellow-legged frog ( Rana muscosa ) has been reduced to <10 isolated populations in the wild. Due to frequent catastrophic events (floods, droughts, wildfires), the recent dynamics of these populations have been erratic, making the future of the species highly uncertain. In 2018, a recovery plan was developed to improve the species status by reducing the impacts of various threats (predation, disease, habitat destruction), as well as reinforcing wild populations through the reintroduction of captive-bred frogs. The short-term goal stated in this plan was to reach a minimum of 20 populations of 50 adults each (hereafter, the 20/50 target ), before the species can be considered for downlisting from the U.S. Endangered Species Act. However, there is no guarantee that this 20/50 target will be sufficient to ensure the species persistence in the long run. Using 19 years of mark-recapture data, we estimated populations' demographic trends and assessed the viability of R. muscosa from a starting state of 20 populations of 50 adults each (i.e., the downlisting criteria). Our results reveal that, from this 20/50 state , the species has high chances of persistence only at a short time horizon (50 years). Moreover, >80% of populations would be extinct 50 years later. Therefore, the species will not be able to persist without implementation of the reintroduction program. We found that it is more important to increase the number of suitable sites occupied by R. muscosa than to simply reinforce or augment existing populations. Expanding the current distribution by establishing new populations at suitable sites, even after the “20 populations” mark has been reached, would increase the likelihood of the species' persistence in the longer term.

California↗
USGS2015

Effects of extreme floods on trout populations and fish communities in a Catskill Mountain river

Summary 1. Extreme hydrologic events are becoming more common with changing climate. Although the impacts of winter and spring floods on lotic ecosystems have been well studied, the effects of summer floods are less well known. 2. The Upper Esopus Creek Basin in the Catskill Mountains, NY, experienced severe flooding from Tropical Storm Irene on 28 August 2011, and peak discharges exceeded the 0.01 annual exceedance probability (>100 year flood) in some reaches. Three years of fish community data from pre-flood surveys at nine sites were compared to data from 2 years of post-flood surveys to evaluate changes in fish communities and populations of brown trout ( Salmo trutta ) and rainbow trout ( Oncorhynchus mykiss ). 3. Basinwide, fish assemblages were not strongly impacted and appeared highly resilient to the effects of the flood. Total density and biomass of fish communities were greater at most sites 10-11 months after the flood than 1 month prior to the flood while richness and diversity were generally unchanged. Community composition did not differ significantly between years or between the pre-and post-flood periods. 4. Although the density of mature brown trout was low at most sites (mean density = 146 fish ha-1), young-of-the-year brown trout reached their highest density (mean = 2312 fish ha-1) during 2012. In contrast, rainbow trout densities declined substantially during the 5-year study and the 2012 year class was small (mean density = 222 fish ha-1). 5. Late summer floods may be less damaging to stream fish communities than winter or spring floods as spawning activity is negligible and early life stages of many species are generally larger and less susceptible to displacement and mortality. Additionally, post-flood conditions may be advantageous for brown trout recruitment.

Freshwater Biology↗
USGS2011

Evidence from lava flows for complex polarity transitions: The new composite Steens Mountain reversal record

Geomagnetic polarity transitions may be significantly more complex than are currently depicted in many sedimentary and lava-flow records. By splicing together paleomagnetic results from earlier studies at Steens Mountain with those from three newly studied sections of Oregon Plateau flood basalts at Catlow Peak and Poker Jim Ridge 70–90 km to the southeast and west, respectively, we provide support for this interpretation with the most detailed account of a magnetic field reversal yet observed in volcanic rocks. Forty-five new distinguishable transitional (T) directions together with 30 earlier ones reveal a much more complex and detailed record of the 16.7 Ma reversed (R)-to-normal (N) polarity transition that marks the end of Chron C5Cr. Compared to the earlier R-T-N-T-N reversal record, the new record can be described as R-T-N-T-N-T-R-T-N. The composite record confirms earlier features, adds new west and up directions and an entire large N-T-R-T segment to the path, and fills in directions on the path between earlier directional jumps. Persistent virtual geomagnetic pole (VGP) clusters and separate VGPs have a preference for previously described longitudinal bands from transition study compilations, which suggests the presence of features at the core–mantle boundary that influence the flow of core fluid and distribution of magnetic flux. Overall the record is consistent with the generalization that VGP paths vary greatly from reversal to reversal and depend on the location of the observer. Rates of secular variation confirm that the flows comprising these sections were erupted rapidly, with maximum rates estimated to be 85–120 m ka −1 at Catlow and 130–195 m ka −1 at Poker Jim South. Paleomagnetic poles from other studies are combined with 32 non-transitional poles found here to give a clockwise rotation of the Oregon Plateau of 11.4°± 5.6° with respect to the younger Columbia River Basalt Group flows to the north and 14.5°± 4.6° with respect to cratonic North America (95 per cent confidence interval).

Geophysical Journal International↗
USGS2010

Landscape genetics of high mountain frog metapopulations

Explaining functional connectivity among occupied habitats is crucial for understanding metapopulation dynamics and species ecology. Landscape genetics has primarily focused on elucidating how ecological features between observations influence gene flow. Functional connectivity, however, may be the result of both these between‐site (landscape resistance) landscape characteristics and at‐site (patch quality) landscape processes that can be captured using network based models. We test hypotheses of functional connectivity that include both between‐site and at‐site landscape processes in metapopulations of Columbia spotted frogs ( Rana luteiventris ) by employing a novel justification of gravity models for landscape genetics (eight microsatellite loci, 37 sites, n = 441). Primarily used in transportation and economic geography, gravity models are a unique approach as flow (e.g. gene flow) is explained as a function of three basic components: distance between sites, production/attraction (e.g. at‐site landscape process) and resistance (e.g. between‐site landscape process). The study system contains a network of nutrient poor high mountain lakes where we hypothesized a short growing season and complex topography between sites limit R. luteiventris gene flow. In addition, we hypothesized production of offspring is limited by breeding site characteristics such as the introduction of predatory fish and inherent site productivity. We found that R. luteiventris connectivity was negatively correlated with distance between sites, presence of predatory fish (at‐site) and topographic complexity (between‐site). Conversely, site productivity (as measured by heat load index, at‐site) and growing season (as measured by frost‐free period between‐sites) were positively correlated with gene flow. The negative effect of predation and positive effect of site productivity, in concert with bottleneck tests, support the presence of source–sink dynamics. In conclusion, gravity models provide a powerful new modelling approach for examining a wide range of both basic and applied questions in landscape genetics.

Idaho↗
USGS2011

Why replication is important in landscape genetics: American black bear in the Rocky Mountains

We investigated how landscape features influence gene flow of black bears by testing the relative support for 36 alternative landscape resistance hypotheses, including isolation by distance (IBD) in each of 12 study areas in the north central U.S. Rocky Mountains. The study areas all contained the same basic elements, but differed in extent of forest fragmentation, altitude, variation in elevation and road coverage. In all but one of the study areas, isolation by landscape resistance was more supported than IBD suggesting gene flow is likely influenced by elevation, forest cover, and roads. However, the landscape features influencing gene flow varied among study areas. Using subsets of loci usually gave models with the very similar landscape features influencing gene flow as with all loci, suggesting the landscape features influencing gene flow were correctly identified. To test if the cause of the variability of supported landscape features in study areas resulted from landscape differences among study areas, we conducted a limiting factor analysis. We found that features were supported in landscape models only when the features were highly variable. This is perhaps not surprising but suggests an important cautionary note – that if landscape features are not found to influence gene flow, researchers should not automatically conclude that the features are unimportant to the species’ movement and gene flow. Failure to investigate multiple study areas that have a range of variability in landscape features could cause misleading inferences about which landscape features generally limit gene flow. This could lead to potentially erroneous identification of corridors and barriers if models are transferred between areas with different landscape characteristics.

Molecular Ecology↗
USGS2007

Rapid plant diversity assessment using a pixel nested plot design: A case study in Beaver Meadows, Rocky Mountain National Park, Colorado, USA

Geospatial statistical modelling and thematic maps have recently emerged as effective tools for the management of natural areas at the landscape scale. Traditional methods for the collection of field data pertaining to questions of landscape were developed without consideration for the parameters of these applications. We introduce an alternative field sampling design based on smaller unbiased random plot and subplot locations called the pixel nested plot (PNP). We demonstrate the applicability of the PNP design of 15 m x 15 m to assess patterns of plant diversity and species richness across the landscape at Rocky Mountain National Park (RMNP), Colorado, USA in a time (cost)-efficient manner for field data collection. Our results produced comparable results to a previous study in the Beaver Meadow study (BMS) area within RMNP, where there was a demonstrated focus of plant diversity. Our study used the smaller PNP sampling design for field data collection which could be linked to geospatial information data and could be used for landscape-scale analyses and assessment applications. In 2003, we established 61 PNP in the eastern region of RMNP. We present a comparison between this approach using a sub-sample of 19 PNP from this data set and 20 of Modified Whittaker nested plots (MWNP) of 20 m x 50 m that were collected in the BMS area. The PNP captured 266 unique plant species while the MWNP captured 275 unique species. Based on a comparison of PNP and MWNP in the Beaver Meadows area, RMNP, the PNP required less time and area sampled to achieve a similar number of species sampled. Using the PNP approach for data collection can facilitate the ecological monitoring of these vulnerable areas at the landscape scale in a time- and therefore cost-effective manner. ?? 2007 The Authors.

Diversity and Distributions↗
USGS2007

A comparison of delta change and downscaled GCM scenarios for three mountainous basins in the United States

Simulated daily precipitation, temperature, and runoff time series were compared in three mountainous basins in the United States: (1) the Animas River basin in Colorado, (2) the East Fork of the Carson River basin in Nevada and California, and (3) the Cle Elum River basin in Washington State. Two methods of climate scenario generation were compared: delta change and statistical downscaling. The delta change method uses differences between simulated current and future climate conditions from the Hadley Centre for Climate Prediction and Research (HadCM2) General Circulation Model (GCM) added to observed time series of climate variables. A statistical downscaling (SDS) model was developed for each basin using station data and output from the National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis regridded to the scale of HadCM2. The SDS model was then used to simulate local climate variables using HadCM2 output for current and future conditions. Surface climate variables from each scenario were used in a precipitation-runoff model. Results from this study show that, in the basins tested, a precipitation-runoff model can simulate realistic runoff series for current conditions using statistically downscaled NCEP output. But, use of downscaled HadCM2 output for current or future climate assessments are questionable because the GCM does not produce accurate estimates of the surface variables needed for runoff in these regions. Given the uncertainties in the GCMs ability to simulate current conditions based on either the delta change or downscaling approaches, future climate assessments based on either of these approaches must be treated with caution.

California, Colorado, Nevada, Washington↗
USGS2021

Climate change and expanding invasive species drive widespread declines of native trout in the northern Rocky Mountains, USA

Climate change and invasive species are major threats to native biodiversity, but few empirical studies have examined their combined effects at large spatial and temporal scales. Using 21,917 surveys collected over 30 years, we quantified the impacts of climate change on the past and future distributions of five interacting native and invasive trout species throughout the northern Rocky Mountains, USA. We found that the occupancy of native bull trout and cutthroat trout declined by 18 and 6%, respectively (1993–2018), and was predicted to decrease by an additional 39 and 16% by 2080. However, reasons for these occupancy reductions markedly differed among species: Climate-driven increases in water temperature and decreases in summer flow likely caused declines of bull trout, while climate-induced expansion of invasive species largely drove declines of cutthroat trout. Our results demonstrate that climate change can affect ecologically similar, co-occurring native species through distinct pathways, necessitating species-specific management actions.

Montana↗