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At least 1,441 records · Page 80Linked to original sources
USGS2017

Potential influence of wildfire in modulating climate-induced forest redistribution in a central Rocky Mountain landscape

Introduction Climate change is expected to impose significant tension on the geographic distribution of tree species. Yet, tree species range shifts may be delayed by their long life spans, capacity to withstand long periods of physiological stress, and dispersal limitations. Wildfire could theoretically break this biological inertia by killing forest canopies and facilitating species redistribution under changing climate. We investigated the capacity of wildfire to modulate climate-induced tree redistribution across a montane landscape in the central Rocky Mountains under three climate scenarios (contemporary and two warmer future climates) and three wildfire scenarios (representing historical, suppressed, and future fire regimes). Methods Distributions of four common tree species were projected over 90 years by pairing a climate niche model with a forest landscape simulation model that simulates species dispersal, establishment, and mortality under alternative disturbance regimes and climate scenarios. Results Three species (Douglas-fir, lodgepole pine, subalpine fir) declined in abundance over time, due to climate-driven contraction in area suitable for establishment, while one species (ponderosa pine) was unable to exploit climate-driven expansion of area suitable for establishment. Increased fire frequency accelerated declines in area occupied by Douglas-fir, lodgepole pine, and subalpine fir, and it maintained local abundance but not range expansion of ponderosa pine. Conclusions Wildfire may play a larger role in eliminating these conifer species along trailing edges of their distributions than facilitating establishment along leading edges, in part due to dispersal limitations and interspecific competition, and future populations may increasingly depend on persistence in locations unfavorable for their establishment.

Idaho↗
USGS2021

Predicting wildfire impacts on the prehistoric archaeological record of the Jemez Mountains, New Mexico, USA

Wildfires of uncharacteristic severity, a consequence of climate changes and accumulated fuels, can cause amplified or novel impacts to archaeological resources. The archaeological record includes physical features associated with human activity; these exist within ecological landscapes and provide a unique long-term perspective on human–environment interactions. The potential for fire-caused damage to archaeological materials is of major concern because these resources are irreplaceable and non-renewable, have social or religious significance for living peoples, and are protected by an extensive body of legislation. Although previous studies have modeled ecological burn severity as a function of environmental setting and climate, the fidelity of these variables as predictors of archaeological fire effects has not been evaluated. This study, focused on prehistoric archaeological sites in a fire-prone and archaeologically rich landscape in the Jemez Mountains of New Mexico, USA, identified the environmental and climate variables that best predict observed fire severity and fire effects to archaeological features and artifacts.

New Mexico↗
USGS2022

Modeled interactions of mountain pine beetle and wildland fire under future climate and management scenarios for three western US landscapes

Mountain pine beetle (MPB) is a native disturbance agent across most pine forests in the western US. Climate changes will directly and indirectly impact frequencies and severities of MPB outbreaks, which can then alter fuel characteristics and wildland fire dynamics via changes in stand structure and composition. To investigate the importance of MPB to past and future landscape dynamics, we used the mechanistic, spatially explicit ecosystem process model FireBGCv2 to quantify interactions among climate, MPB, wildfire, fire suppression, and fuel management under historical and projected future climates for three western US landscapes. We compared simulated FireBGCv2 output from three MPB modules (none, simple empirical, and complex mechanistic) using three focus variables and six exploratory variables to evaluate the importance of MPB to landscape dynamics.

Fire Ecology↗
USGS2026

Relationship of satellite-derived fire severity to archaeological fire severity and fire effects in the Jemez Mountains, New Mexico, USA

Background Archaeological attributes important for determining cultural affiliation, site age, or artifact origin can be damaged or destroyed by wildfires. Satellite-derived fire severity products are used in post-fire rapid response to prioritize and guide stabilization and preservation activities, but their ability to predict archaeological fire impacts has not yet been tested. We compared the severity of fire from Burned Area Reflectance Classification (BARC) maps with ground-based observations of fire severity (“archaeological fire severity”) and archaeological impacts for 904 prehistoric or historic sites within three wildfires in the Jemez Mountains of north-central New Mexico, U.S. Results from this unique study inform archaeological preservation in the context of wildfires and fire management. Results We found a statistically significant, moderately strong association between BARC and archaeological fire severity and a high likelihood that sites with a low BARC fire severity also had a low archaeological fire severity designation. Sites of moderate or high BARC severity were less likely to have a matching severity classification in post-fire assessments, and BARC maps tended to identify as unburned areas where archaeologists determined that sites were burned at low severity. Wildfire of any severity resulted in measurable impacts to archaeological architecture, features, or artifacts at some sites, with increasing proportion of sites impacted at moderate versus low BARC severity, but fire impacts were also observed at sites classified by BARC as unburned. Conclusions Generally, BARC maps provide good assessment of the severity of fire and its effects on archaeological resources, particularly for areas burned at low severity. In areas of moderate or high fire severity, BARC maps may not consistently identify sites with a high need for assessment, and archaeological fire effects can also be present at sites classified by BARC as unburned. Adoption of standardized post-fire archaeological assessments across wildfires and regions, exploration of alternative fire mapping products, and continued research on the fire environments that produce archaeological fire effects can enhance archaeological preservation and post-fire response.

New Mexico↗
USGS2009

Near‐surface evaluation of Ball Mountain Dam, Vermont, using multi‐channel analysis of surface waves (MASW) and refraction tomography seismic methods on land‐streamer data

A limited seismic investigation of Ball Mountain Dam, an earthen dam near Jamaica, Vermont, was conducted using multiple seismic methods including multi‐channel analysis of surface waves (MASW), refraction tomography, and vertical seismic profiling (VSP). The refraction and MASW data were efficiently collected in one survey using a towed land streamer containing vertical‐displacement geophones and two seismic sources, a 9‐kg hammer at the beginning of the spread and a 40‐kg accelerated weight drop one spread length from the geophones, to obtain near‐ and far‐offset data sets. The quality of the seismic data for the purposes of both refraction and MASW analyses was good for near offsets, decreasing in quality at farther offsets, thus limiting the depth of investigation to about 12 m. Refraction tomography and MASW analyses provided 2D compressional (Vp) and shear‐wave (Vs) velocity sections along the dam crest and access road, which are consistent with the corresponding VSP seismic velocity estimates from nearby wells. The velocity sections helped identify zonal variations in both Vp and Vs (rigidity) properties, indicative of material heterogeneity or dynamic processes (e.g. differential settlement) at specific areas of the dam. The results indicate that refraction tomography and MASW methods are tools with significant potential for economical, non‐invasive characterization of construction materials at earthen dam sites.

Vermont↗
USGS2014

Geophysical interpretation of U, Th, and rare earth element mineralization of the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeast Alaska

A prospectivity map for rare earth element (REE) mineralization at the Bokan Mountain peralkaline granite complex, Prince of Wales Island, southeastern Alaska, was calculated from high-resolution airborne gamma-ray data. The map displays areas with similar radioelement concentrations as those over the Dotson REE-vein-dike system, which is characterized by moderately high %K, eU, and eTh (%K, percent potassium; eU, equivalent parts per million uranium; and eTh, equivalent parts per million thorium). Gamma-ray concentrations of rocks that share a similar range as those over the Dotson zone are inferred to locate high concentrations of REE-bearing minerals. An approximately 1300-m-long prospective tract corresponds to shallowly exposed locations of the Dotson zone. Prospective areas of REE mineralization also occur in continuous swaths along the outer edge of the pluton, over known but undeveloped REE occurrences, and within discrete regions in the older Paleozoic country rocks. Detailed mineralogical examinations of samples from the Dotson zone provide a means to understand the possible causes of the airborne Th and U anomalies and their relation to REE minerals. Thorium is sited primarily in thorite. Uranium also occurs in thorite and in a complex suite of ± Ti ± Nb ± Y oxide minerals, which include fergusonite, polycrase, and aeschynite. These oxides, along with Y-silicates, are the chief heavy REE (HREE)-bearing minerals. Hence, the eU anomalies, in particular, may indicate other occurrences of similar HREE-enrichment. Uranium and Th chemistry along the Dotson zone showed elevated U and total REEs east of the Camp Creek fault, which suggested the potential for increased HREEs based on their association with U-oxide minerals. A uranium prospectivity map, based on signatures present over the Ross-Adams mine area, was characterized by extremely high radioelement values. Known uranium deposits were identified in the U-prospectivity map, but the largest tract occurs over a radioelement-rich granite phase within the pluton that is likely not related to mineralization. Neither mineralization type displays a well-defined airborne magnetic signature.

Alaska↗
USGS2012

Digital outcrop model of stratigraphy and breccias of the southern Franklin Mountains, El Paso, Texas

This chapter reviews and synthesizes the lithostratigraphy, biostratigraphy, chronostratigraphy, and breccia types of the southwestern part of the great American carbonate bank in the southern Franklin Mountains (SFM), El Paso, Texas. Primary stratigraphic units of focus are the Lower Ordovician El Paso and Upper Ordovician Montoya Groups. These groups preserve breccias formed by collapse of a paleocave system. Precambrian and Silurian units are discussed in the context of breccia clast composition and relative timing of breccia emplacement. Specific attention is paid to the juxtaposition of the top-Sauk second-order supersequence unconformity between the El Paso and Montoya Groups and its relationship to breccias above and below it. The unconformity represents a 10-m.y. exposure event that separates Upper and Lower Ordovician carbonates. The top-Sauk exposure has been previously documented as a significant karst horizon across much of North America. The breccias of the SFM were previously described as the result of collapsed paleocaves that formed during subaerial exposure related to the Sauk-Tippecanoe unconformity. A new approach in this work uses traditional field mapping combined with high-resolution ( 1-m [ 3.3-ft] point spacing) airborne light detection and ranging (LIDAR) data over 24 km 2 (9 mi 2 ) to map breccia and relevant stratal surfaces. Airborne LIDAR data were used to create a digital outcrop model of the SFM from which a detailed (1:2000 scale) geologic map was created. The geologic map includes formation, fault, and breccia contacts. The digital outcrop model was used to interpret three-dimensional spatial relationships of breccia bodies with respect to the current understanding of the tectonic and stratigraphic evolution of the SFM. The data presented here are used to discuss potential stratigraphic, temporal, and tectonic controls on the formation of caves within the study area that eventually collapsed to form the breccias currently exposed in outcrop.

Texas↗
USGS1986

Minturn and Sangre de Cristo formations of Southern Colorado: A prograding fan delta and alluvial fan sequence shed from the ancestral Rocky Mountains

The Middle Pennsylvania!) Minturn Formation and the Pennsylvanian-Permian Sangre de Cristo Formation of the northern Sangre de Cristo Range form a thick progradational sequence of coarse clastic sediments. These sediments were deposited along the western margin of the central Colorado trough during uplift of the late Paleozoic Uncompahgre highland, a major structural and topographic feature of the Ancestral Rocky Mountains. The Minturn is composed mostly of sandstone and shale deposited by fan deltas that prograded into the central Colorado trough. The Minturn of the northern Sangre de Cristo Range is divisible into a turbidite-bearing facies, a limestone-bearing facies, and a redbed facies. The turbidite-bearing facies is interpreted as deposits of fan deltas that prograded onto the sea bottom below wave base. The limestone-bearing facies is interpreted as deposits of fan deltas that prograded onto a shallow sea bottom above wave base. In this facies, sandstones containing deltaic foresets overlie thin shallow marine limestones and are considered diagnostic of that facies. Both facies contain thick intervals of sandstone and shale interpreted as deltaic and alluvial deposits. Where it onlaps the Uncompahgre highland, the lower part of the Minturn Formation contains quartzose and arkosic redbeds of probable alluvial origin. The continental Sangre de Cristo Formation conformably overlies the Minturn Formation basinward, but it unconformably overlies the Minturn and Precambrian basement near the Uncompahgre highland. The Sangre de Cristo contains two facies. A sandstone facies consists of fining-upward cycles of red conglomeratic sandstone and siltstone interpreted as braided stream deposits on distal parts of alluvial fans. A conglomerate facies (Crestone Conglomerate Member) consists of poorly sorted conglomerates interpreted as debris flow and mudflow deposits and sorted conglomerate and sandstone interpreted as streamflow and sheetflow deposits on proximal parts of alluvial fans. The fan deltas and alluvial fans that deposited the Minturn and Sangre de Cristo formations probably developed in response to faulting and uplift of the Uncompahgre highland. The highland rose at least three times from Middle Pennsylvanian to Early Permian time. Later, during the Laramide orogeny, the faulted boundary between the highland and the central Colorado trough was destroyed by thrusting. The boundary faults were not strike-slip, as shown by the distribution of clasts in conglomerates directly downstream from identical Precambrian rocks that represent part of the highland.

Colorado↗
USGS2013

An integrated model of environmental effects on growth, carbohydrate balance, and mortality of Pinus ponderosa forests in the southern Rocky Mountains

Climate-induced tree mortality is an increasing concern for forest managers around the world. We used a coupled hydrologic and ecosystem carbon cycling model to assess temperature and precipitation impacts on productivity and survival of ponderosa pine ( Pinus ponderosa ). Model predictions were evaluated using observations of productivity and survival for three ponderosa pine stands located across an 800 m elevation gradient in the southern Rocky Mountains, USA, during a 10-year period that ended in a severe drought and extensive tree mortality at the lowest elevation site. We demonstrate the utility of a relatively simple representation of declines in non-structural carbohydrate (NSC) as an approach for estimating patterns of ponderosa pine vulnerability to drought and the likelihood of survival along an elevation gradient. We assess the sensitivity of simulated net primary production, NSC storage dynamics, and mortality to site climate and soil characteristics as well as uncertainty in the allocation of carbon to the NSC pool. For a fairly wide set of assumptions, the model estimates captured elevational gradients and temporal patterns in growth and biomass. Model results that best predict mortality risk also yield productivity, leaf area, and biomass estimates that are qualitatively consistent with observations across the sites. Using this constrained set of parameters, we found that productivity and likelihood of survival were equally dependent on elevation-driven variation in temperature and precipitation. Our results demonstrate the potential for a coupled hydrology-ecosystem carbon cycling model that includes a simple model of NSC dynamics to predict drought-related mortality. Given that increases in temperature and in the frequency and severity of drought are predicted for a broad range of ponderosa pine and other western North America conifer forest habitats, the model potentially has broad utility for assessing ecosystem vulnerabilities.

Jemez Mountains, Rocky Mountains↗
USGS2015

Photosynthetic and growth response of sugar maple ( Acer saccharum Marsh.) mature trees and seedlings to calcium, magnesium, and nitrogen additions in the Catskill Mountains, NY, USA

Decline of sugar maple in North American forests has been attributed to changes in soil calcium (Ca) and nitrogen (N) by acidic precipitation. Although N is an essential and usually a limiting factor in forests, atmospheric N deposition may cause N-saturation leading to loss of soil Ca. Such changes can affect carbon gain and growth of sugar maple trees and seedlings. We applied a 2 2 factorial arrangement of N and dolomitic limestone containing Ca and Magnesium (Mg) to 12 forest plots in the Catskill Mountain region of NY, USA. To quantify the short-term effects, we measured photosynthetic-light responses of sugar maple mature trees and seedlings two or three times during two summers. We estimated maximum net photosynthesis ( An-max ) and its related light intensity ( PAR at An-max ), apparent quantum efficiency ( A qe ), and light compensation point ( LCP ). To quantify the long-term effects, we measured basal area of living mature trees before and 4 and 8 years after treatment applications. Soil and foliar chemistry variables were also measured. Dolomitic limestone increased Ca, Mg, and pH in the soil Oe horizon. Mg was increased in the B horizon when comparing the plots receiving N with those receiving CaMg. In mature trees, foliar Ca and Mg concentrations were higher in the CaMg and N+CaMg plots than in the reference or N plots; foliar Ca concentration was higher in the N+CaMg plots compared with the CaMg plots, foliar Mg was higher in the CaMg plots than the N+CaMg plots; An-max was maximized due to N+CaMg treatment; A qe decreased by N addition; and PAR at An-max increased by N or CaMg treatments alone, but the increase was maximized by their combination. No treatment effect was detected on basal areas of living mature trees four or eight years after treatment applications. In seedlings, An-max was increased by N+CaMg addition. The reference plots had an open herbaceous layer, but the plots receiving N had a dense monoculture of common woodfern in the forest floor, which can impede seedling survival.

New York↗
USGS2014

Reanalysis of historical U.S. Geological Survey sediment samples for geochemical data from the western part of the Wrangellia terrane, Anchorage, Gulkana, Healy, Mt. Hayes, Nabesna, and Talkeetna Mountains quadrangles, Alaska

The State of Alaska’s Strategic and Critical Minerals (SCM) Assessment project, a State-funded Capital Improvement Project (CIP), is designed to evaluate Alaska’s statewide potential for SCM resources. The SCM Assessment is being implemented by the Alaska Division of Geological & Geophysical Surveys (DGGS), and involves obtaining new airborne-geophysical, geological, and geochemical data. For the geochemical part of the SCM Assessment, thousands of historical geochemical samples from DGGS, U.S. Geological Survey (USGS), and U.S. Bureau of Mines archives are being reanalyzed by DGGS using modern, quantitative, geochemical-analytical methods. The objective is to update the statewide geochemical database to more clearly identify areas in Alaska with SCM potential. The USGS is also undertaking SCM-related geologic studies in Alaska through the federally funded Alaska Critical Minerals cooperative project. DGGS and USGS share the goal of evaluating Alaska’s strategic and critical minerals potential and together created a Letter of Agreement (signed December 2012) and a supplementary Technical Assistance Agreement (#14CMTAA143458) to facilitate the two agencies’ cooperative work. Under these agreements, DGGS contracted the USGS in Denver to reanalyze historical USGS sediment samples from Alaska. For this report, DGGS funded reanalysis of 1,682 historical USGS sediment samples from the statewide Alaska Geochemical Database Version 2.0 (AGDB2; Granitto and others, 2013). Samples were chosen from an area covering the western half of the Wrangellia Terrane in the Anchorage, Gulkana, Healy, Mt. Hayes, Nabesna, and Talkeetna Mountains quadrangles of south-central Alaska (fig. 1). USGS was responsible for sample retrieval from the Denver warehouse through the final quality assurance/quality control (QA/QC) of the geochemical analyses obtained through the USGS contract lab. The new geochemical data are published in this report as a coauthored DGGS report, and will be incorporated into the statewide geochemical databases of both agencies.

Alaska↗
USGS2019

U-Pb and Lu-Hf isotope, age, and trace-element data from zircons at four sites in the western Alaska Range and Talkeetna Mountains, Alaska

This Division of Geological & Geophysical Surveys (DGGS) Raw Data File presents U-Pb geochronology and Lu-Hf isotopic compositions, age-dating results, and additional trace-elemental composition of zircons from four granitoids sampled during investigations by DGGS geologists in the western Alaska Range and the Talkeetna Mountains. The purpose of the Lu-Hf and U-Pb isotopic study was to better understand the Jurassic through early Tertiary magmatic and tectonic evolution of the Alaska Range and the significance of that magmatism for the formation of metallic mineral deposits. The U-Pb isotopic data also serve to further refine the crystallization age of plutons, which were previously ambiguous in 40Ar/39Ar geochronology studies.

Alaska↗
USGS2020

U-Pb geochronology of igneous and detrital zircon samples from the Tok River area, eastern Alaska Range, and Talkeetna Mountains, Alaska

This Alaska Division of Geological & Geophysical Surveys (DGGS) Raw Data File presents U-Pb zircon geochronology results from selected igneous, meta-igneous, and metasedimentary rocks collected during the Tok River and Wrangellia geologic mapping projects in the eastern Alaska Range and the northwestern Talkeetna Mountains, Alaska. The purpose of these analyses is to better constrain the age of select geologic units encountered during the mapping projects.

Alaska↗
USGS2013

Spatial variation in breeding habitat selection by Cerulean Warblers ( Setophaga cerulea ) throughout the Appalachian Mountains

Studies of habitat selection are often of limited utility because they focus on small geographic areas, fail to examine behavior at multiple scales, or lack an assessment of the fitness consequences of habitat decisions. These limitations can hamper the identification of successful site-specific management strategies, which are urgently needed for severely declining species like Cerulean Warblers ( Setophaga cerulea ). We assessed how breeding habitat decisions made by Cerulean Warblers at multiple scales, and the subsequent effects of these decisions on nest survival, varied across the Appalachian Mountains. Selection for structural habitat features varied substantially among areas, particularly at the territory scale. Males within the least-forested landscapes selected microhabitat features that reflected more closed-canopy forest conditions, whereas males in highly forested landscapes favored features associated with canopy disturbance. Selection of nest-patch and nest-site attributes by females was more consistent across areas, with females selecting for increased tree size and understory cover and decreased basal area and midstory cover. Floristic preferences were similar across study areas: White Oak ( Quercus alba ), Cucumber-tree ( Magnolia acuminata ), and Sugar Maple ( Acer saccharum ) were preferred as nest trees, whereas red oak species (subgenus Erythrobalanus ) and Red Maple ( A. rubrum ) were avoided. The habitat features that were related to nest survival also varied among study areas, and preferred features were negatively associated with nest survival at one area. Thus, our results indicate that large-scale spatial heterogeneity may influence local habitat-selection behavior and that it may be necessary to articulate site-specific management strategies for Cerulean Warblers.

Ohio, Kentucky, Tennessee, West Virginia↗
USGS1960

The stoneroller, Campostoma anomalum (Rafinesque), in Great Smoky Mountains National Park

The stoneroller (Campostoma anomalum) is one of the more important fish in Great Smoky Mountains National Park because of its abundance and habits. Although esteemed locally as a food and a bait fish, the stoneroller is exploited but little since the fishing regulations which govern the utilization of game fishes afford it a large measure of protection. Distribution is controlled by gradient with an upper limit of 4.4 percent. Stonerollers limit reproduction of rainbow trout (Salmo gairdneri) by destroying trout redds. Artificial reduction of stoneroller populations is not considered a necessary management procedure.

North Carolina, Tennessee↗
USGS2003

Evidence of sexually dimorphic introgression in Pinaleno Mountain Apache trout

The high-elevation headwater streams of the Pinaleno Mountains support small populations of threatened Apache trout Oncorhynchus apache that were stocked following the chemical removal of nonnative salmonids in the 1960s. A fisheries survey to assess population composition, growth, and size structure confirmed angler reports of infrequent occurrences of Oncorhynchus spp. exhibiting the external morphological characteristics of both Apache trout and rainbow trout O. mykiss. Nonlethal tissue samples were collected from 50 individuals in the headwaters of each stream. Mitochondrial DNA (mtDNA) sequencing and amplification of nuclear microsatellite loci were used to determine the levels of genetic introgression by rainbow trout in Apache trout populations at these locations. Sexually dimorphic introgression from the spawning of male rainbow trout with female Apache trout was detected using mtDNA and microsatellites. Estimates of the degree of hybridization based on three microsatellite loci were 10-88%. The use of nonlethal DNA genetic analyses can supplement information obtained from standard survey methods and be useful in assessing the relative importance of small and sensitive populations with a history of nonnative introductions.

North American Journal of Fisheries Management↗
USGS2008

Distribution, occupancy, and habitat correlates of American martens (Martes americana) in Rocky Mountain National Park, Colorado

A clear understanding of habitat associations of martens (Martes americana) is necessary to effectively manage and monitor populations. However, this information was lacking for martens in most of their southern range, particularly during the summer season. We studied the distribution and habitat correlates of martens from 2004 to 2006 in Rocky Mountain National Park (RMNP) across 3 spatial scales: site-specific, home-range, and landscape. We used remote-sensored cameras from early August through late October to inventory occurrence of martens and modeled occurrence as a function of habitat and landscape variables using binary response (BR) and binomial count (BC) logistic regression, and occupancy modeling (OM). We also assessed which was the most appropriate modeling technique for martens in RMNP. Of the 3 modeling techniques, OM appeared to be most appropriate given the explanatory power of derived models and its incorporation of detection probabilities, although the results from BR and BC provided corroborating evidence of important habitat correlates. Location of sites in the western portion of the park, riparian mixed-conifer stands, and mixed-conifer with aspen patches were most frequently positively correlated with occurrence of martens, whereas more xeric and open sites were avoided. Additionally, OM yielded unbiased occupancy values ranging from 91% to 100% and 20% to 30% for the western and eastern portions of RMNP, respectively. ?? 2008 American Society of Mammalogists.

Journal of Mammalogy↗