Search USGS⌕ Search

SEARCH · Search USGS

Results for “Weather Climate and Society”

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 37 records · Page 2Linked to original sources
USGS2018

Effects of distribution, behavior, and climate on mule deer survival

Mule deer ( Odocoileus hemionus hemionus ) populations in North America are a valuable economic wildlife resource, with the managed harvest of this species reflecting societal values and recreational opportunities in many parts of the western United States. Managing mule deer populations while allowing for harvest requires an understanding of the species’ population dynamics, including the specific factors associated with population change. We conducted a 7-year (2005–2012) study designed to investigate habitat use and survival of mule deer in eastern Oregon, USA. We used known-fate data for 408 adult female radio-collared mule deer to estimate monthly survival rates and to investigate factors that might affect these rates, including seasonal distribution, temporal effects (seasonal, annual, and trends across season and year), movement behavior, and local weather and regional climatic covariates. Variation in survival rates of female mule deer was best explained by an additive effect of migration behavior, differences in survival during the fall migration period compared to the rest of the annual cycle, and precipitation levels on winter ranges of individual deer. Estimates of annual survival were higher for migrants (0.81–0.82), compared to residents (0.76–0.77). Survival was lower for migrants and residents during fall migration (Oct–Nov) and higher amounts of winter precipitation increased survival of both groups. The results of our study suggest that migrating to potentially higher quality summer foraging areas outweighed the cost of traveling through unfamiliar habitats and energy expenditure associated with migration. © 2018 The Wildlife Society.

Oregon↗
USGS2015

Climate change and prairie pothole wetlands: mitigating water-level and hydroperiod effects through upland management

Prairie pothole wetlands offer crucial habitat for North America’s waterfowl populations. The wetlands also support an abundance of other species and provide ecological services valued by society. The hydrology of prairie pothole wetlands is dependent on atmospheric interactions. Therefore, changes to the region’s climate can have profound effects on wetland hydrology. The relevant literature related to climate change and upland management effects on prairie pothole wetland water levels and hydroperiods was reviewed. Climate change is widely expected to affect water levels and hydroperiods of prairie pothole wetlands, as well as the biota and ecological services that the wetlands support. In general, hydrologic model projections that incorporate future climate change scenarios forecast lower water levels in prairie pothole wetlands and longer periods spent in a dry condition, despite potential increases in precipitation. However, the extreme natural variability in climate and hydrology of prairie pothole wetlands necessitates caution when interpreting model results. Recent changes in weather patterns throughout much of the Prairie Pothole Region have been in increased precipitation that results in increased water inputs to wetlands above losses associated with warmer temperatures. However, observed precipitation increases are within the range of natural climate variability and therefore, may not persist. Identifying management techniques with the potential to affect water inputs to prairie pothole wetlands would provide increased options for managers when dealing with the uncertainties associated with a changing climate. Several grassland management techniques (for example, grazing and burning) have the potential to affect water levels and hydroperiods of prairie pothole by affecting infiltration, evapotranspiration, and snow deposition.

Prairie Pothole Region↗
USGS1996

Lower and lower Middle Pennsylvanian fluvial to estuarine deposition, central Appalachian basin: Effects of eustasy, tectonics, and climate

Interpretations of Pennsylvanian sedimentation and peat accumulation commonly use examples from the Appalachian basin because of the excellent outcrops and large reserve of coal (>100 billion metric tons) in the region. Particularly controversial is the origin of Lower and lower Middle Pennsylvanian quartzose sandstones; beach-barrier, marine-bar, tidal-strait, and fluvial models all have been applied to a series of sand bodies along the western outcrop margin of the basin. Interpretations of these sandstones and their inferred lateral relationships are critical for understanding the relative degree of eustatic, tectonic, and climatic controls on Early Pennsylvanian sedimentation. Cross sections utilizing >1000 subsurface records and detailed sedimentological analysis of the Livingston Conglomerate, Rockcastle Sandstone, Corbin Sandstone, and Pine Creek sandstone (an informal member) of the Breathitt Group were used to show that each of the principal quartzose sandstones on the margin of the central Appalachian basin contains both fluvial and marginal marine facies. The four sandstones are fluvially dominated and are inferred to represent successive bed-load trunk systems of the Appalachian foreland. Base-level rise and an associated decrease in extra-basinal sediment at the end of each fluvial episode led to the development of local estuaries and marine reworking of the tops of the sand belts. Each of the sand belts is capped locally by a coal, regardless of whether the upper surfaces of the sand belts are of fluvial or estuarine origin, suggesting allocyclic controls on deposition. Peats were controlled by a tropical ever-wet climate, which also influenced sandstone composition through weathering of stored sands in slowly aggrading braidplains. Recurrent stacking of thick, coarse-grained, fluvial deposits with extra-basinal quartz pebbles; dominance of bed-load fluvial–lowstand deposits over mixed-load, estuarine-transgressive deposits; thinning of sand belts around tectonic highs and along faults; cratonward shift and amalgamation of successive sand belts on the margin of the basin; and truncation of successive sand belts toward the fault-bound margin of the basin are interpreted as regional responses to Alleghenian tectonism, inferred to have been the dominant control on accommodation space and sediment flux in the Early Pennsylvanian basin.

Geological Society of America Bulletin↗
USGS2008

Effects of weather on survival in populations of boreal toads in Colorado

Understanding the relationships between animal population demography and the abiotic and biotic elements of the environments in which they live is a central objective in population ecology. For example, correlations between weather variables and the probability of survival in populations of temperate zone amphibians may be broadly applicable to several species if such correlations can be validated for multiple situations. This study focuses on the probability of survival and evaluates hypotheses based on six weather variables in three populations of Boreal Toads (Bufo boreas) from central Colorado over eight years. In addition to suggesting a relationship between some weather variables and survival probability in Boreal Toad populations, this study uses robust methods and highlights the need for demographic estimates that are precise and have minimal bias. Capture-recapture methods were used to collect the data, and the Cormack-Jolly-Seber model in program MARK was used for analysis. The top models included minimum daily winter air temperature, and the sum of the model weights for these models was 0.956. Weaker support was found for the importance of snow depth and the amount of environmental moisture in winter in modeling survival probability. Minimum daily winter air temperature was positively correlated with the probability of survival in Boreal Toads at other sites in Colorado and has been identified as an important covariate in studies in other parts of the world. If air temperatures are an important component of survival for Boreal Toads or other amphibians, changes in climate may have profound impacts on populations. Copyright 2008 Society for the Study of Amphibians and Reptiles.

Journal of Herpetology↗
USGS2010

Testing alternative models of climate-mediated extirpations

Biotic responses to climate change will vary among taxa and across latitudes, elevational gradients, and degrees of insularity. However, due to factors such as phenotypic plasticity, ecotypic variation, and evolved tolerance to thermal stress, it remains poorly understood whether losses should be greatest in populations experiencing the greatest climatic change or living in places where the prevailing climate is closest to the edge of the species' bioclimatic envelope (e.g., at the hottest, driest sites). Research on American pikas (Ochotona princeps) in montane areas of the Great Basin during 1994-1999 suggested that 20th-century population extirpations were predicted by a combination of biogeographic, anthropogenic, and especially climatic factors. Surveys during 2005-2007 documented additional extirpations and within-site shifts of pika distributions at remaining sites. To evaluate the evidence in support of alternative hypotheses involving effects of thermal stress on pikas, we placed temperature sensors at 156 locations within pika habitats in the vicinity of 25 sites with historical records of pikas in the Basin. We related these time series of sensor data to data on ambient temperature from weather stations within the Historical Climate Network. We then used these highly correlated relationships, combined with long-term data from the same weather stations, to hindcast temperatures within pika habitats from 1945 through 2006. To explain patterns of loss, we posited three alternative classes of direct thermal stress: (1) acute cold stress (number of days below a threshold temperature); (2) acute heat stress (number of days above a threshold, temperature); and. (3) chronic heat stress (average summer temperature). Climate change was defined as change in our thermal metrics between two 31-y.r periods: 1945-1975 and 1976-2006. We found that patterns of persistence were well predicted by metrics of climate. Our best models suggest some effects of climate change; however, recent and long-term metrics of chronic heat stress and acute cold stress, neither previously recognized as sources of stress for pikas, were some of the best predictors of pika persistence. Results illustrate that extremely rapid distributional shifts can be explained by climatic influences and have implications for conservation topics such as reintroductions and early-warning indicators. ?? 2010 by the Ecological society of America.

Ecological Applications↗
USGS2023

Extracting exotic annual grass phenology and climate relations in western U.S. rangeland ecoregions

This research builds upon the extensive body of work to model exotic annual grass (EAG) characteristics and invasion. EAGs increase wildland fire risk and intensifies wildland fire behavior in western U.S. rangelands. Therefore, understanding characteristics of EAG growth increases understanding of its dynamics and can inform rangeland management decisions. To better understand EAG phenology and spatial distribution, monthly weather (precipitation, minimum and maximum temperature) variables were analyzed for 24 level III ecoregions. This research characterizes EAGs’ phenology identified by a normalized difference vegetation index (NDVI) threshold-based interpolation technique. An EAG phenology metric model was used to estimate a growing season dynamic for the years 2017–2021 for shrub and herbaceous land cover types in the western conterminous United States (66% of the area). The EAG phenology metrics include six growing season metrics such as start of season time, end of season time, and time of maximum NDVI during the growing season. The models’ cross validation results for Pearson’s r ranged from 0.88 to 0.95. Increased understanding of the effects that weather conditions have on EAG growth and spatial distribution can help land managers develop time-sensitive plans to protect entities deemed valuable to society like native habitat, wildlife, recreational areas, and air quality.

western rangeland ecoregions↗
USGS2019

Soil warming effects on tropical forests with highly weathered soils

The tropics are a region encircling the equator, delineated to the north by the Tropic of Cancer (23°26′14.0″N) and to the south by the Tropic of Capricorn (23°26′14.0″S). While we often think of the tropics as consistently warm and wet throughout the year, in reality, the tropics maintain a myriad of climates. Of the 116 Holdridge life zones (a global bioclimatic classification scheme), the tropics contain more life zones than the sum of all the planet's other geographic regions combined ( Holdridge, 1967 ). In addition to high climatic diversity, the tropics support a wide range of parent materials, landforms, geomorphic characteristics, and soil ages, and maintain all 12 soil types of the USDA soil taxonomy system ( Palm et al., 2007 ; Porder et al., 2007 ; Quesada et al., 2010 ; Richter and Babbar, 1991 ; Sanchez, 1977 ; Soil Survey Staff, 2006 ; Townsend et al., 2008 ). Accordingly, there is no single representative tropical ecosystem. Given the diversity of tropical biomes, this chapter will focus specifically on tropical forested ecosystems and their responses to warming because of their global importance, potential sensitivity to change, and the fact that an improved understanding of how these ecosystems may respond to warmer climate conditions is of significant importance to ecology and society. Furthermore, while generally considering all tropical forest types, emphasis in this chapter is on the humid tropics for which we have most data.

Book chapter↗
USGS1971

An evaluation of procedures used in computing chemical denudation rates

Computations of chemical denudation rates (that is, the average rate of lowering of the earth's crust by chemical processes) should be based only upon those components of dissolved loads of streams that are derived from chemical weathering of rocks and soils, even though identification of those components is difficult and imprecise. Past computations of chemical denudation rates exaggerated by 1.4 to 2.4 times the significance of this process because they were calculated from total dissolved loads. Identification of separate denudation and nondenudation components in a water analysis can be done most readily for streams in crystalline silicate rock terrane where commonly 25 to 55 percent of the dissolved solids are HCO 3 −1 , SO 4 −2 , Cl −1 , and NO 3 −1 that cannot be derived from the underlying rock; instead these ions are derived either directly from the atmosphere or from atmosphere-biosphere interactions. Most of the remaining solutes are derived from chemical weathering or rainfall, or both. Existing data are often insufficient to separate these two components, but atmospheric contributions to dissolved loads of dilute natural waters are substantial. The commonly observed increased concentration of dissolved solids in chemically polluted rivers is produced by concentration of natural dissolved loads by evaporation, and by addition of solutes not present in natural waters. Concentration of natural solutes represents a modification of natural denudation processes that does not change the rate of denudation. Addition of new solutes represents man-induced, accelerated chemical denudation. Extrapolation of modern chemical denudation rates to geologic situations is extremely imprecise because of uncertainties in assessing man's influence on present dissolved loads, in reconstructing the number and magnitude of past climatic changes, and in evaluating the effects of evolving flora and fauna.

Bulletin of the Geological Society of America↗
USGS2011

Cold-climate slope deposits and landscape modifications of the Mid-Atlantic Coastal Plain, Eastern USA

The effects of Pleistocene cold-climate geomorphology are distributed across the weathered and eroded Mid-Atlantic Coastal Plain uplands from the Wisconsinan terminal moraine south to Tidewater Virginia. Cold-climate deposits and landscape modifications are superimposed on antecedent landscapes of old, weathered Neogene upland gravels and Pleistocene marine terraces that had been built during warm periods and sea-level highstands. In New Jersey, sequences of surficial deposits define a long history of repeating climate change events. To the south across the Delmarva Peninsula and southern Maryland, most antecedent topography has been obscured by Late Pleistocene surficial deposits. These are spatially variable and are collectively described as a cold-climate alloformation. The cold-climate alloformation includes time-transgressive details of climate deterioration from at least marine isotope stage (MIS) 4 through the end of MIS 2. Some deposits and landforms within the alloformation may be as young as the Younger Dryas. Southwards along the trend of the Potomac River, these deposits and their climatic affinities become diffused. In Virginia, a continuum of erosion and surficial deposits appears to be the product of ‘normal’ temperate, climate-forced processes. The cold-climate alloformation and more temperate deposits in Virginia are being partly covered by Holocene alluvium and bay mud.

Geological Society Special Publication↗
USGS2013

Perception, experience, and indigenous knowledge of climate change and variability: the case of Accra, a sub-Saharan African city

Several recent international assessments have concluded that climate change has the potential to reverse the modest economic gains achieved in many developing countries over the past decade. The phenomenon of climate change threatens to worsen poverty or burden populations with additional hardships, especially in poor societies with weak infrastructure and economic well-being. The importance of the perceptions, experiences, and knowledge of indigenous peoples has gained prominence in discussions of climate change and adaptation in developing countries and among international development organizations. Efforts to evaluate the role of indigenous knowledge in adaptation planning, however, have largely focused on rural people and their agricultural livelihoods. This paper presents the results of a study that examines perceptions, experiences, and indigenous knowledge relating to climate change and variability in three communities of metropolitan Accra, which is the capital of Ghana. The study design is based on a three-part conceptual framework and interview process involving risk mapping, mental models, and individual stressor cognition. Most of the residents interviewed in the three communities of urban Accra attributed climate change to the combination of deforestation and the burning of firewood and rubbish. None of the residents associated climate change with fossil fuel emissions from developed countries. Numerous potential adaptation strategies were suggested by the residents, many of which have been used effectively during past drought and flood events. Results suggest that ethnic residential clustering as well as strong community bonds in metropolitan Accra have allowed various groups and long-settled communities to engage in the sharing and transmission of knowledge of weather patterns and trends. Understanding and building upon indigenous knowledge may enhance the design, acceptance, and implementation of climate change adaptation strategies in Accra and urban regions of other developing nations.

Accra↗
USGS2023

CONUS404: The NCAR-USGS 4-km long-term regional hydroclimate reanalysis over the CONUS

A unique, high-resolution, hydroclimate reanalysis, 40-plus-year (October 1979–September 2021), 4 km (named as CONUS404), has been created using the Weather Research and Forecasting Model by dynamically downscaling of the fifth-generation European Centre for Medium-Range Weather Forecasts (ECMWF) atmospheric reanalysis of the global climate dataset (ERA5) over the conterminous United States. The paper describes the approach for generating the dataset, provides an initial evaluation, including biases, and indicates how interested users can access the data. The motivation for creating this National Center for Atmospheric Research (NCAR)–U.S. Geological Survey (USGS) collaborative dataset is to provide research and end-user communities with a high-resolution, self-consistent, long-term, continental-scale hydroclimate dataset appropriate for forcing hydrological models and conducting hydroclimate scientific analyses over the conterminous United States. The data are archived and accessible on the USGS Black Pearl tape system and on the NCAR supercomputer Campaign storage system.

Continental United States↗
USGS2009

Variability of the Southern California wave climate and implications for sediment transport

We analyzed wave and wind data from 18 buoys in the Southern California Bight to characterize the spatial and temporal variability of the regional wave climate. Point Conception shelters most of the Bight from being directly impacted by North Pacific weather. The wave height inside the sheltered zone and to the east of the Channel Islands is less than half the wave height in the open ocean to the west. Within the sheltered Bight, storm waves (by proxy of being greater than the 95th percentile wave height for more than 6 hours) are mainly from the west, but long period swells (T p >15 seconds) are mainly from the south-southwest. There are on average two to four storms during each winter month (November-March) and fewer than two storms per month for the rest of the year. The Channel Islands selectively block the westerly swells and make the wave climate in the Santa Barbara Channel different from the rest of the sheltered Bight. A statistically significant wave-height minimum exists in the area offshore Dana Point and Oceanside. The multiyear (2-23 years) wave-data records from all 18 buoys show negligible temporal trend, positive or negative. Like the wave climate, the long-term probability of sediment transport on the continental shelves of the Bight displays large difference between the sheltered and open-ocean (near Point Conception) sites. The return period of incipient sediment motion on the sheltered shelf breaks (one to five months) is at least two orders of magnitude longer than that on the Point Conception shelf break (0.6 day). Similar to the spatial distribution of wave heights, there is a systematic return-period maximum on the shelf off Dana Point and Oceanside. ?? 2009 The Geological Society of America.

Special Paper of the Geological Society of America↗
USGS2018

Land cover and land use change

Climate can affect and be affected by changes in land cover (the physical features that cover the land such as trees or pavement) and land use (human management and activities on land, such as mining or recreation). A forest, for instance, would likely include tree cover but could also include areas of recent tree removals currently covered by open grass areas. Land cover and use are inherently coupled: changes in land-use practices can change land cover, and land cover enables specific land uses. Understanding how land cover, use, condition, and management vary in space and time is challenging. Changes in land cover can occur in response to both human and climate drivers. For example, demand for new settlements often results in the permanent loss of natural and working lands, which can result in localized changes in weather patterns, temperature, and precipitation. Aggregated over large areas, these changes have the potential to influence Earth’s climate by altering regional and global circulation patterns, changing the albedo (reflectivity) of Earth’s surface, and changing the amount of carbon dioxide (CO 2 ) in the atmosphere. Conversely, climate change can also influence land cover, resulting in a loss of forest cover from climate-related increases in disturbances, the expansion of woody vegetation into grasslands, and the loss of beaches due to coastal erosion amplified by rises in sea level. Land use is also changed by both human and climate drivers. Land-use decisions are traditionally based on short-term economic factors. Land-use changes are increasingly being influenced by distant forces due to the globalization of many markets. Land use can also change due to local, state, and national policies, such as programs designed to remove cultivation from highly erodible land to mitigate degradation, legislation to address sea level rise in local comprehensive plans, or policies that reduce the rate of timber harvest on federal lands. Technological innovation has also influenced land-use change, with the expansion of cultivated lands from the development of irrigation technologies and, more recently, decreases in demand for agricultural land due to increases in crop productivity. The recent expansion of oil and gas extraction activities throughout large areas of the United States demonstrates how policy, economics, and technology can collectively influence and change land use and land cover. Decisions about land use, cover, and management can help determine society’s ability to mitigate and adapt to climate change.

Report↗
USGS2017

Engaging the user community for advancing societal applications of the Surface Water Ocean Topography mission

Scheduled for launch in 2021, the Surface Water and Ocean Topography (SWOT) mission will be a truly unique mission that will provide high-temporal-frequency maps of surface water extents and elevation variations of global water bodies (lakes/reservoirs, rivers, estuaries, oceans, and sea ice) at higher spatial resolution than is available with current technologies (Biancamaria et al. 2016; Alsdorf et al. 2007). The primary instrument on SWOT is based on a Ka-band radar interferometer (KaRIN), which uses radar interferometery technology. The satellite will fly two radar antennas at either end of a 10-m (33 ft) mast, allowing it to measure the elevation of the surface along a 120-km (75 mi)-wide swath below. The availability of high-frequency and high-resolution maps of elevations and extents for surface water bodies and oceans will present unique opportunities to address numerous societally relevant challenges around the globe (Srinivasan et al. 2015). These opportunities may include such diverse and far-ranging applications as fisheries management, flood inundation mapping/risk mitigation/forecasting, wildlife conservation, global data assimilation for improving forecast of ocean tides and weather, reservoir management, climate change impacts and adaptation, and river discharge estimation, among others. Although SWOT is a research mission and not scheduled for launch for another 4 years, there is a need to build engagement within the application community now and to explore how best to advance the societal relevance and benefits of the SWOT mission from concept to reality. The SWOT Applications Working Group organized a workshop on 5–6 April 2017 at the U.S. Geological Survey (USGS) headquarters in Reston, Virginia. The goal of the workshop was to understand and communicate how the applications community can use SWOT data to address problems of profound societal relevance.

Bulletin of the American Meteorological Society↗
USGS2001

Impact of climate and parent material on chemical weathering in Loess-derived soils of the Mississippi River valley

Peoria Loess-derived soils on uplands east of the Mississippi River valley were studied from Louisiana to Iowa, along a south-to-north gradient of decreasing precipitation and temperature. Major element analyses of deep loess in Mississippi and Illinois show that the composition of the parent material is similar in the northern and southern parts of the valley. We hypothesized that in the warmer, wetter parts of the transect, mineral weathering should be greater than in the cooler, drier parts of the transect. Profile average values of CaO/TiO 2 , MgO/TiO 2 , K 2 O/TiO 2 and Na 2 O/TiO 2 , Sr/Zr, Ba/Zr, and Rb/Zr represent proxies for depletion of loess minerals such as calcite, dolomite, hornblende, mica, and plagioclase. All ratios show increases from south to north, supporting the hypothesis of greater chemical weathering in the southern part of the valley. An unexpected result is that profile average values of Al 2 O 3 /TiO 2 and Fe 2 O 3 /TiO 2 (proxies for the relative abundance of clay minerals) show increases from south to north. This finding, while contrary to the evidence of greater chemical weathering in the southern part of the transect, is consistent with an earlier study which showed higher clay contents in Bt horizons of loess-derived soils in the northern part of the transect. We hypothesize that soils in the northern part of the valley received fine-grained loess from sources to the west of the Mississippi River valley either late in the last glacial period, during the Holocene or both. In contrast, soils in the southern part of the valley were unaffected by such additions.

Arkansas, Illinois, Iowa, Kentucky, Louisiana, Mis↗
USGS1993

Relict colluvial boulder deposits as paleoclimatic indicators in the Yucca Mountain region, southern Nevada

Early to middle Pleistocene boulder deposits are common features on southern Nevada hillslopes. These darkly varnished, ancient colluvial deposits stand but in stark contrast to the underlying light-colored bedrock of volcanic tuffs, and they serve as minor divides between drainage channels on modern hillslopes. To demonstrate the antiquity of these stable hillslope features, six colluvial boulder deposits from Yucca Mountain, Nye County, Nevada, were dated by cation- ratio dating of rock varnish accreted on boulder surfaces. Estimated minimum ages of these boulder deposits range from 760 to 170 ka. Five additional older deposits on nearby Skull and Little Skull Mountains and Buckboard Mesa yielded cation-ratio minimum-age estimates of 1.38 Ma to 800 ka. An independent cosmogenic chlorine-36 surface exposure date was obtained on one deposit, which confirms an estimated early to middle Quaternary age. These deposits have provided the oldest age estimates for unconsolidated hillslope deposits in the southwestern United States. We suggest that the colluvial boulder deposits were produced during early and middle Pleistocene glacial/pluvial episodes and were stabilized during the transition to drier interglacial climates. By comparison to modern periglacial environments, winter minimum monthly temperatures of -3 to -5 °C were necessary to initiate freeze-thaw conditions of such vigor to physically weather relatively large volumes of large boulders from the upper hillslopes of the Yucca Mountain area. These conditions imply that early and middle Pleistocene glacial winter temperatures were at least 1 to 3 °C colder than existed during the last Pleistocene glacial episode and 7 to 9 °C colder than present. We conclude that at least several early and middle Pleistocene glacial episodes were colder, and perhaps wetter, than glacial episodes of the late Pleistocene in the southern Great Basin. Geomorphic processes necessary to form these colluvial boulder deposits are not active on modern hillslopes in the southern Great Basin. In addition, the lack of young, relatively unvarnished colluvial boulder deposits on these hillslopes suggests that boulder-forming conditions did not exist during the late Pleistocene in this region. Modern semiarid hillslope processes primarily erode colluvium during infrequent high-intensity storms. The preservation of old, thin hillslope deposits and the less-than-2-m incision by hillslope runoff adjacent to these deposits, however, indicate that extremely low denudation rates have occurred on resistant volcanic hillslopes in the southern Great Basin during Quaternary time.

Nevada↗
USGS2025

Spring weather influences breeding propensity, the most important productivity component for Arctic-nesting lesser snow geese

Animal reproduction is composed of several stages, which collectively determine overall productivity. Yet, it is not fully understood how different productivity components contribute to population change. To bridge this gap, we leveraged integrated population modelling and transient life-table response experiments, together with population-level data on lesser snow geese ( Anser caerulescens caerulescens ) breeding on Wrangel Island, Russia, from 1970 to 2022. We assessed contributions of breeding propensity, clutch size, nest success, egg survival, hatching success and pre-fledging survival to population change, and tested hypotheses about the effects of environmental drivers and density dependence on different components. Breeding propensity contributed the most to variation in population growth, followed by nest success. These two components were negatively affected by the timing of snow melt. We found no overall deleterious effects of climate change on productivity. Density dependence had a positive effect on multiple productivity components, likely through predator swamping. Our results show the importance of breeding propensity to the population dynamics of this long-lived animal, which is notable because this productivity component is often overlooked. Our results also demonstrate that the effects of environmental conditions and density dependence can differ among animal populations of different sizes, locations and life histories.

Wrangel Island↗
USGS2016

Analysis of hydrologic and geochemical time-series data at James Cave, Virginia: Implications for epikarst influence on recharge in Appalachian karst aquifers

The epikarst, which consists of highly weathered rock in the upper vadose zone of exposed karst systems, plays a critical role in determining the hydrologic and geochemical characteristics of recharge to an underlying karst aquifer. This study utilized time series (2007–2014) of hydrologic and geochemical data of drip water collected within James Cave, Virginia, to examine the influence of epikarst on the quantity and quality of recharge in a mature, doline-dominated karst terrain. Results show a strong seasonality of both hydrology and geochemistry of recharge, which has implications for management of karst aquifers in temperate climatic zones. First, recharge (discharge from the epikarst to the underlying aquifer) reaches a maximum between late winter and early spring, with the onset of the recharge season ranging from as early as December to as late as March during the study period. The timing and duration of the recharge season were found to be a function of precipitation in excess of evapotranspiration on a seasonal time scale. Secondly, seasonally variable residence times for water in the epikarst influence rock-water interaction and, hence, the geochemical characteristics of recharge. Overall, results highlight the strong and complex influence that the epikarst has on karst recharge, which requires long-term and high-resolution data sets to accurately understand and quantify.

Virginia↗