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At least 1,045 records · Page 58Linked to original sources
USGS2019

Seed bank community and soil texture relationships in a cold desert

Sustainable dryland management depends on understanding environmental factors driving composition of current and future ecological communities. While there has been extensive research on aboveground plant communities, less is known about belowground soil seed bank communities, which can reflect both past and potential future communities. In the Colorado Plateau of the western United States, we explored aboveground and belowground plant communities and how they varied across sites with similar climate but contrasting soil textures. We found that aboveground vegetation and belowground seed bank community composition each varied significantly among sites. However, we also observed marked aboveground-belowground compositional dissimilarity across sites, suggesting that the two spatially-associated communities may respond differently to the same environmental gradient. Lastly, we found that cheatgrass seed prevalence (Bromus tectorum) – one of the region’s major exotic invasive plants – varied strongly by soil texture, a finding with potential implications for invasive species management. From our research findings, we highlight two general patterns for dryland managers. Firstly, we show aboveground and belowground plant communities will not always respond to the same environmental changes in a coordinated manner. Secondly, the data underscore a large potential role for soil texture in mediating the plant community responses to other environmental factors.

Utah↗
USGS2025

Bioclimatic, demographic, and anthropogenic correlates of grizzly bear activity patterns in the Greater Yellowstone Ecosystem

Plasticity of diel activity rhythms may be a key element for adaptations of wildlife populations to changing environmental conditions. In the last decades, grizzly bears Ursus arctos in the Greater Yellowstone Ecosystem (GYE) have experienced notable environmental fluctuations, including changes in availability of food sources and severe droughts. Although substantial research has been conducted on grizzly bear diets, space use, and demographic parameters, studies on factors that may influence their diel activity patterns are lacking. We investigated diel activity of grizzly bears in the GYE as a function of anthropogenic landscape modification, maximum daily ambient temperature, drought severity, and bear density. Specifically, we used accelerometry readings of 169 bears (39 females, 130 males) from 2009 to 2022 to compute three complementary activity measures, hourly intensity of activity, daily active minutes, and active bout length, each used as a response variable within a Bayesian modeling framework. Grizzly bears generally exhibited bimodal diel activity, with crepuscular peaks and slight variations across seasons. Females with young (i.e. cubs or yearlings) were an exception, with more pronounced diurnal activity patterns, possibly as a strategy to avoid infanticide by dominant males. Landscape modification and maximum ambient temperature were the factors most strongly associated with activity patterns of grizzly bears, with greater nocturnality observed in lone females and males as these factors increased. Females with young were comparatively less affected. The GYE is changing because of increasing land development, human recreation pressures, and effects of climate change. Given their greater diurnal activity compared with other cohorts, female grizzly bears with dependent offspring may be more constrained in their ability to modify activity patterns. Our findings add to a growing body of research emphasizing the importance of the temporal dimension of wildlife behavior as a critical factor in assessing species adaptability and vulnerability in a changing world.

Idaho, Montana, Wyoming↗
USGS2020

A guidebook to spatial datasets for conservation planning under climate change in the Pacific Northwest

This guidebook provides user-friendly overviews of a variety of spatial datasets relevant to conservation and management of natural resources in the face of climate change in the Pacific Northwest, United States. Each guidebook chapter was created using a standardized template to summarize a spatial dataset or a group of closely related datasets. Datasets were selected according to standardized criteria based on input through a collaborative process involving researchers and natural-resource managers throughout the Pacific Northwest region. In each chapter, basic spatial and temporal information is provided for the dataset, along with a conceptual overview, glossary of key terms, links to download data and supporting documentation, a brief methods summary describing how the dataset was created, guidelines for dataset interpretation, assessment of uncertainties along with evaluation of caveats and simplifying assumptions, and information about potential and actual conservation applications of the dataset. Collectively, this information provides natural-resource managers with “snapshots” of a variety of datasets representing diverse processes and conditions, including climate projections, changes in hydrologic conditions, vegetation and fire-regime shifts, animal habitat changes, species movements, and topographic and soil conditions relevant to climate change. Along with other types of data and site-specific information, the datasets described in this guidebook have the potential to inform management of valued natural resources throughout the Pacific Northwest region in the context of adaptation to changing climate conditions.

Idaho, Montana, Oregon, Washington↗
USGS2021

Long-term ecosystem and biogeochemical research in Loch Vale watershed, Rocky Mountain National Park, Colorado

Loch Vale watershed was instrumented in 1983 with initial support from the National Acid Precipitation Assessment Program to ask whether ecosystems of Rocky Mountain National Park (RMNP) were affected by acidic atmospheric deposition. Research and monitoring activities were expanded in 1991 by the U.S. Geological Survey Water, Energy, and Biogeochemical Budgets program to understand the processes, and their interactions, controlling water, energy, and biogeochemical fluxes. With help from many collaborators we have characterized trends and patterns in atmospheric deposition, climate, and hydrology, including glaciers and other ice features. Instead of acidic deposition, we documented high atmospheric inputs of reactive nitrogen (Nr), and have studied the ecological consequences in soils, surface water, and vegetation. Using paleolimnology, we documented the onset of human-caused change to lake primary producers ca. 1950 in response to increased Nr deposition and warming. Our results provided the basis for the Colorado Nitrogen Deposition Reduction Plan, a state policy that aims to reduce Nr emissions to protect resources in RMNP by 2032. Carbon cycle research revealed mountain wetlands now release more carbon than they store, and respiration and methane flux occurs even during winter through deep snow packs. Trend analyses found export of Nr to be closely tied to atmospheric inputs, but can lag in response to drought. Current research explores consequences of the combination of warming, changes in precipitation dynamics, and atmospheric deposition of Nr and dust on stream and lake CO 2 dynamics, lake biology and trophic state, and soil carbon composition. Dramatic increases in park visitors have prompted studies on the effects of recreational use on water quality. New tools such as remote sensing and high frequency instream water quality sensors are being applied to lake and stream studies. Monitoring, combined with experiments, models, and spatial comparisons is an essential foundation for science-based resource management.

Colorado↗
USGS2025

Ranking river basins for stream temperature research and monitoring in the contiguous United States

There is a need to prioritize research and data collection in river basins by integrating information from environmental, ecological, and socioeconomic datasets to maintain acceptable water quality for human uses and ecosystem health. Multiple anthropogenic and natural stressors are responsible for driving changes in stream temperatures that can alter ecosystems and degrade water quality. These stressors are variable spatially and temporally, which can be challenging for prioritizing monitoring and research. In this study, an evaluation of variables related to stream temperature was performed for 163 candidate basins of the contiguous United States to highlight potential focal areas. Thirty variables were combined in six components: anthropogenic forcing, natural forcing, climate change, ecological sensitivity, socioeconomic sensitivity, and data availability. The components were incorporated into three themes: vulnerability of streams to thermal change, vulnerability of ecosystems, and vulnerability of communities. By evaluating each theme separately, patterns of vulnerability and potential resiliency were identified as well as consistency in ranks within the themes. For example, results of the national scale ranking indicated the Southern California Coastal basin (within California-Nevada region) was the highest-ranking priority in vulnerability of streams to thermal change and vulnerability of ecosystems. The analysis also identified vulnerable basins with gaps in monitoring. For example, the Missouri-Oahe basin (within the Northern High Plains region) was the highest-ranking priority for vulnerable communities with limitations in data availability. The ranking approach provides insight into basins that are resilient and are ideal candidates for monitoring and research.

Journal of Hydrology↗
USGS2023

Early Pliocene (Zanclean) stratigraphic framework for PRISM5/PlioMIP3 time slices

Global reconstructions of Pliocene climate provide important insights into how the climate system operates under elevated temperatures and atmospheric CO2 levels. These reconstructions have been used extensively in paleoclimate modeling experiments for comparison to simulated conditions, and as boundary conditions.Most previous work focused on the Late Pliocene interval known as the mid Piacenzian Warm Period (mPWP), the interval originally identified by the U.S. Geological Survey Pliocene Research, Interpretation and Synoptic Mapping Project (PRISM) as the PRISM interval or Mid Pliocene Warm Period. The term Mid Pliocene Warm Period is a misnomer due to changes to the geological time scale, and its use should be discontinued. The Pliocene Model Intercomparison Project (PlioMIP), now in its third phase, is expanding to include a focus on the Early Pliocene (Zanclean). PlioMIP3 experiments will allow comparison of environmental and climatic conditions before and after closure of the Central American Seaway (CAS). PlioMIP3 used the annual insolation pattern at the top of the atmosphere to determine time slices in the Zanclean that have orbital configurations that are most similar to modern. Two have been selected by PlioMIP and adopted by PRISM for inclusion in future studies: PRISM5.1 (4.474 Ma) and PRISM5.2 (4.870 Ma). Here we establish the stratigraphic framework for these Early Pliocene time slices and furnish information to help locate these intervals in proxy records of paleoenvironmental data using oxygen isotope stratigraphy, paleomagnetic stratigraphy, biostratigraphy, and biochronology (calibrated planktic foraminifer and calcareous nannofossil events).

Stratigraphy↗
USGS2025

Clarifying the trophic state concept to advance macroscale freshwater science and management

For over a century, ecologists have used the concept of trophic state (TS) to characterize an aquatic ecosystem's biological productivity. However, multiple TS classification schemes, each relying on a variety of measurable parameters as proxies for productivity, have emerged to meet use-specific needs. Frequently, chlorophyll a, phosphorus, and Secchi depth are used to classify TS based on autotrophic production, whereas phosphorus, dissolved organic carbon, and true color are used to classify TS based on both autotrophic and heterotrophic production. Both classification approaches aim to characterize an ecosystem's function broadly, but with varying degrees of autotrophic and heterotrophic processes considered in those characterizations. Moreover, differing classification schemes can create inconsistent interpretations of ecosystem integrity. For example, the US Clean Water Act focuses exclusively on algal threats to water quality, framed in terms of eutrophication in response to nutrient loading. This usage lacks information about non-algal threats to water quality, such as dystrophication in response to dissolved organic carbon loading. Consequently, the TS classification schemes used to identify eutrophication and dystrophication may refer to ecosystems similarly (e.g., oligotrophic and eutrophic), yet these categories are derived from different proxies. These inconsistencies in TS classification schemes may be compounded when interdisciplinary projects employ varied TS frameworks. Even with these shortcomings, TS can still be used to distill information on complex aquatic ecosystem function into a set of generalizable expectations. The usefulness of distilling complex information into a TS index is substantial such that usage inconsistencies should be explicitly addressed and resolved. To emphasize the consequences of diverging TS classification schemes, we present three case studies for which an improved understanding of the TS concept advances freshwater research, management efforts, and interdisciplinary collaboration. To increase clarity in TS, the aquatic sciences could benefit from including information about the proxy variables, ecosystem type, as well as the spatiotemporal domains used to classify TS. As the field of aquatic sciences expands and climatic irregularity increases, we highlight the importance of re-evaluating fundamental concepts, such as TS, to ensure their compatibility with evolving science.

Ecosphere↗
USGS2023

Increased salinity decreases annual gross primary productivity at a Northern California brackish tidal marsh

Tidal marshes sequester 11.4–87.0 Tg C yr −1 globally, but climate change impacts can threaten the carbon capture potential of these ecosystems. Tidal marshes occur across a wide range of salinity, with brackish marshes (0.5–18 ppt (parts per thousand)) dominating global tidal marsh extents. A diverse mix of freshwater- and saltwater-tolerant plant and microbial communities has led researchers to predict that carbon cycling in brackish wetlands may be less sensitive to changes in salinity than fresh- or saltwater wetlands. Rush Ranch, a well-monitored brackish tidal wetland of the San Francisco Bay National Estuarine Research Reserve, experiences highly variable annual salinity regimes. Within a five-year period (2014–2018), Rush Ranch experienced particularly extreme drought-induced salinization during the 2014 and 2015 growing seasons. During drought years, tidal channel salinity rose from a 15 year baseline of 4.7 ppt to growing season peaks of 10.3 ppt and 12.5 ppt. Continuous eddy covariance data from 2014 to 2018 demonstrate that during drought summers, gross primary productivity (GPP) decreased by 24%, whereas ecosystem respiration remained similar among all five years. Stepwise linear regression revealed that salinity, not air temperature or tidal height, was the dominant driver of annual GPP. A random forest model trained to predict GPP based on environmental data from low salinity years (i.e. naive to salinization) significantly over predicted GPP in drought years. When growing season salinities were doubled, annual estimates of net ecosystem exchange of CO 2 decreased by up to 30%. These results provide ecosystem-scale evidence that increased salinity influences CO 2 fluxes dominantly through reductions in GPP. This relationship provides a starting point for incorporating the effect of changes in salinity in wetland carbon models, which could improve wetland carbon forecasting and management for climate resilience.

California↗
USGS2017

Deep-sea coral research and technology program: Alaska deep-sea coral and sponge initiative final report

Deep-sea coral and sponge ecosystems are widespread throughout most of Alaska’s marine waters. In some places, such as the central and western Aleutian Islands, deep-sea coral and sponge resources can be extremely diverse and may rank among the most abundant deep-sea coral and sponge communities in the world. Many different species of fishes and invertebrates are associated with deep-sea coral and sponge communities in Alaska. Because of their biology, these benthic invertebrates are potentially impacted by climate change and ocean acidification. Deepsea coral and sponge ecosystems are also vulnerable to the effects of commercial fishing activities. Because of the size and scope of Alaska’s continental shelf and slope, the vast majority of the area has not been visually surveyed for deep-sea corals and sponges. NOAA’s Deep Sea Coral Research and Technology Program (DSCRTP) sponsored a field research program in the Alaska region between 2012–2015, referred to hereafter as the Alaska Initiative. The priorities for Alaska were derived from ongoing data needs and objectives identified by the DSCRTP, the North Pacific Fishery Management Council (NPFMC), and Essential Fish Habitat-Environmental Impact Statement (EFH-EIS) process. This report presents the results of 15 projects conducted using DSCRTP funds from 2012-2015. Three of the projects conducted as part of the Alaska deep-sea coral and sponge initiative included dedicated at-sea cruises and fieldwork spread across multiple years. These projects were the eastern Gulf of Alaska Primnoa pacifica study, the Aleutian Islands mapping study, and the Gulf of Alaska fish productivity study. In all, there were nine separate research cruises carried out with a total of 109 at-sea days conducting research. The remaining projects either used data and samples collected by the three major fieldwork projects or were piggy-backed onto existing research programs at the Alaska Fisheries Science Center (AFSC).

NOAA Technical Memorandum↗
USGS2010

Ecoregions and stream morphology in eastern Oklahoma

Broad-scale variables (i.e., geology, topography, climate, land use, vegetation, and soils) influence channel morphology. How and to what extent the longitudinal pattern of channel morphology is influenced by broad-scale variables is important to fluvial geomorphologists and stream ecologists. In the last couple of decades, there has been an increase in the amount of interdisciplinary research between fluvial geomorphologists and stream ecologists. In a historical context, fluvial geomorphologists are more apt to use physiographic regions to distinguish broad-scale variables, while stream ecologists are more apt to use the concept of an ecosystem to address the broad-scale variables that influence stream habitat. For this reason, we designed a study using ecoregions, which uses physical and biological variables to understand how landscapes influence channel processes. Ecoregions are delineated by similarities in geology, climate, soils, land use, and potential natural vegetation. In the fluvial system, stream form and function are dictated by processes observed throughout the fluvial hierarchy. Recognizing that stream form and function should differ by ecoregion, a study was designed to evaluate how the characteristics of stream channels differed longitudinally among three ecoregions in eastern Oklahoma, USA: Boston Mountains, Ozark Highlands, and Ouachita Mountains. Channel morphology of 149 stream reaches was surveyed in 1st- through 4th-order streams, and effects of drainage area and ecoregion on channel morphology was evaluated using multiple regressions. Differences existed (?????0.05) among ecoregions for particle size, bankfull width, and width/depth ratio. No differences existed among ecoregions for gradient or sinuosity. Particle size was smallest in the Ozark Highlands and largest in the Ouachita Mountains. Bankfull width was larger in the Ozark Highlands than in the Boston Mountains and Ouachita Mountains in larger streams. Width/depth ratios of the Boston Mountains and Ozark Highlands were not statistically different. Significant differences existed, however, between the Boston Mountains and Ozark Highlands when compared individually to the Ouachita Mountains. We found that ecoregions afforded a good spatial structure that can help in understanding longitudinal trends in stream reach morphology surveyed at the reach scale. The hierarchy of the fluvial system begins within a broad, relatively homogenous setting that imparts control on processes that affect stream function. Ecoregions provide an adequate regional division to begin a large-scale geomorphic study of processes in stream channels. ?? 2010 Elsevier B.V.

Geomorphology↗
USGS2020

High‐resolution dynamically downscaled rainfall and temperature projections for ecological life zones within Puerto Rico and for the U.S. Virgin Islands

The weather research and forecasting (WRF) model and a combination of the regional spectral model (RSM) and the Japanese Meteorological Agency Non‐Hydrostatic Model (NHM) were used to dynamically downscale selected CMIP5 global climate models to provide 2‐km projections with hourly model output for Puerto Rico and the U.S. Virgin Islands. Two 20‐year time slices were downscaled for historical (1986–2005) and future (2041–2060) periods following RCP8.5. Projected changes to mean and extreme temperature and precipitation were quantified for Holdridge life zones within Puerto Rico and for the U.S. Virgin Islands. The evaluation reveals a persistent cold bias for all islands in the U.S. Caribbean, a dry bias across Puerto Rico, and a wet bias on the windward side of mountains within the U.S. Virgin Islands. Despite these biases, model simulations show a robust drying pattern for all islands that is generally larger for Puerto Rico (25% annual rainfall reduction for some life zones) than the U.S. Virgin Islands (12% island average). The largest precipitation reductions are found during the more convectively active afternoon and evening hours. Within Puerto Rico, the model uncertainty increases for the wetter life zones, especially for precipitation. Across the life zones, both models project unprecedented maximum and minimum temperatures that may exceed 200 days annually above the historical baseline with only small changes to the frequency of extreme rainfall. By contrast, in the U.S. Virgin Islands, there is no consensus on the location of the largest drying relative to the windward and leeward side of the islands. However, the models project the largest increases in maximum temperature on the southern side of St. Croix and in higher elevations of St. Thomas and St. John.

Puerto Rico↗
USGS2024

Hurricane wave energy dissipation and wave-driven currents over a fringing reef

In 2018, two successive tropical cyclones, Hurricane Hector and Hurricane Lane, generated waves that impacted the Hawaiian Islands. This study investigates wave breaking over a broad fringing reef and aims to quantify the magnitudes and length scales of the corresponding wave-driven circulation using detailed field observations and numerical models corresponding to these wave events. Detailed wave and current measurements were collected across a 1200-m wide cross-reef transect off the coral reef-lined south coast of Moloka’i, Hawai’i. High-resolution numerical model grids were developed to resolve reef features and the coupled Delft3D-SWAN modeling system was applied to simulate spectral wave transformation and wave-driven currents for these two energetic ocean wave events generated by distant passing hurricanes. The results indicate that the wave-driven circulation is generally weak, with current speeds typically less than 0.15 m/s for the wave conditions generated by Hurricane Lane, with significant wave heights up to 1.9 m. Higher energy dissipation rates from larger waves up to 2.5 m breaking during Hurricane Hector resulted in stronger observed currents up to approximately 0.3 m/s. However, the model results show that these currents are confined to the wave-breaking region over the upper fore reef in a narrow (100–300 m) region near the reef crest, and weaker flows of less than 0.1 m/s are generated over the shallow and wide reef flat. Wave heights across the reef flat are less than 0.5 m and are controlled by the tidal water levels. The coral reef structures therefore provide significant protection for the coastline even during large wave and variable sea level conditions. Climate change is likely to increase sea level and storm intensity, the combination of which will influence wave transmission over fringing reefs that may degrade habitat, fueling the need for further research on changing conditions on coral reef-lined coasts.

Hawaii↗
USGS2008

Sediment and nutrient delivery from thermokarst features in the foothills of the North Slope, Alaska: Potential impacts on headwater stream ecosystems

Permafrost is a defining characteristic of the Arctic environment. However, climate warming is thawing permafrost in many areas leading to failures in soil structure called thermokarst. An extensive survey of a 600 km2 area in and around the Toolik Lake Natural Research Area (TLNRA) revealed at least 34 thermokarst features, two thirds of which were new since ???1980 when a high resolution aerial survey of the area was done. Most of these thermokarst features were associated with headwater streams or lakes. We have measured significantly increased sediment and nutrient loading from thermokarst features to streams in two well-studied locations near the TLNRA. One small thermokarst gully that formed in 2003 on the Toolik River in a 0.9 km2 subcatchment delivered more sediment to the river than is normally delivered in 18 years from 132 km2 in the adjacent upper Kuparuk River basin (a long-term monitoring reference site). Ammonium, nitrate, and phosphate concentrations downstream from a thermokarst feature on Imnavait Creek increased significantly compared to upstream reference concentrations and the increased concentrations persisted over the period of sampling (1999-2005). The downstream concentrations were similar to those we have used in a long-term experimental manipulation of the Kuparuk River and that have significantly altered the structure and function of that river. A subsampling of other thermokarst features from the extensive regional survey showed that concentrations of ammonium, nitrate, and phosphate were always higher downstream of the thermokarst features. Our previous research has shown that even minor increases in nutrient loading stimulate primary and secondary production. However, increased sediment loading could interfere with benthic communities and change the responses to increased nutrient delivery. Although the terrestrial area impacted by thermokarsts is limited, the aquatic habitat altered by these failures can be extensive. If warming in the Arctic foothills accelerates thermokarst formation, there may be substantial and wide-spread impacts on arctic stream ecosystems that are currently poorly understood. Copyright 2008 by the American Geophysical Union.

Journal of Geophysical Research G: Biogeosciences↗
USGS2014

Long-term citizen-collected data reveal geographical patterns and temporal trends in lake water clarity

We compiled a lake-water clarity database using publicly available, citizen volunteer observations made between 1938 and 2012 across eight states in the Upper Midwest, USA. Our objectives were to determine (1) whether temporal trends in lake-water clarity existed across this large geographic area and (2) whether trends were related to the lake-specific characteristics of latitude, lake size, or time period the lake was monitored. Our database consisted of >140,000 individual Secchi observations from 3,251 lakes that we summarized per lake-year, resulting in 21,020 summer averages. Using Bayesian hierarchical modeling, we found approximately a 1% per year increase in water clarity (quantified as Secchi depth) for the entire population of lakes. On an individual lake basis, 7% of lakes showed increased water clarity and 4% showed decreased clarity. Trend direction and strength were related to latitude and median sample date. Lakes in the southern part of our study-region had lower average annual summer water clarity, more negative long-term trends, and greater inter-annual variability in water clarity compared to northern lakes. Increasing trends were strongest for lakes with median sample dates earlier in the period of record (1938–2012). Our ability to identify specific mechanisms for these trends is currently hampered by the lack of a large, multi-thematic database of variables that drive water clarity (e.g., climate, land use/cover). Our results demonstrate, however, that citizen science can provide the critical monitoring data needed to address environmental questions at large spatial and long temporal scales. Collaborations among citizens, research scientists, and government agencies may be important for developing the data sources and analytical tools necessary to move toward an understanding of the factors influencing macro-scale patterns such as those shown here for lake water clarity.

Illinois, Indiana, Iowa, Michigan, Minnesota, Miss↗
USGS2015

Effects of climate change on long-term population growth of pronghorn in an arid environment

Climate often drives ungulate population dynamics, and as climates change, some areas may become unsuitable for species persistence. Unraveling the relationships between climate and population dynamics, and projecting them across time, advances ecological understanding that informs and steers sustainable conservation for species. Using pronghorn ( Antilocapra americana ) as an ecological model, we used a Bayesian approach to analyze long-term population, precipitation, and temperature data from 18 populations in the southwestern United States. We determined which long-term (12 and 24 months) or short-term (gestation trimester and lactation period) climatic conditions best predicted annual rate of population growth (λ). We used these predictions to project population trends through 2090. Projections incorporated downscaled climatic data matched to pronghorn range for each population, given a high and a lower atmospheric CO 2 concentration scenario. Since the 1990s, 15 of the pronghorn populations declined in abundance. Sixteen populations demonstrated a significant relationship between precipitation and λ, and in 13 of these, temperature was also significant. Precipitation predictors of λ were highly seasonal, with lactation being the most important period, followed by early and late gestation. The influence of temperature on λ was less seasonal than precipitation, and lacked a clear temporal pattern. The climatic projections indicated that all of these pronghorn populations would experience increased temperatures, while the direction and magnitude of precipitation had high population-specific variation. Models predicted that nine populations would be extirpated or approaching extirpation by 2090. Results were consistent across both atmospheric CO 2 concentration scenarios, indicating robustness of trends irrespective of climatic severity. In the southwestern United States, the climate underpinning pronghorn populations is shifting, making conditions increasingly inhospitable to pronghorn persistence. This realization informs and steers conservation and management decisions for pronghorn in North America, while exemplifying how similar research can aid ungulates inhabiting arid regions and confronting similar circumstances elsewhere.

Ecosphere↗
USGS2017

U.S. Geological Survey Cooperative Fish and Wildlife Research Units Program—2016–2017 Research Abstracts

The U.S. Geological Survey (USGS) has several strategic goals that focus its efforts on serving the American people. The USGS Ecosystems Mission Area has responsibility for the following objectives under the strategic goal of “Science to Manage and Sustain Resources for Thriving Economies and Healthy Ecosystems”: Understand, model, and predict change in natural systems Conserve and protect wildlife and fish species and their habitats Reduce or eliminate the threat of invasive species and wildlife disease This report provides abstracts of the majority of ongoing research investigations of the USGS Cooperative Fish and Wildlife Research Units program and is intended to complement the 2016 Cooperative Research Units Program Year in Review Circular 1424 ( https://doi.org/10.3133/cir1424 ). The report is organized by the following major science themes that contribute to the objectives of the USGS: Advanced Technologies Climate Science Decision Science Ecological Flows Ecosystem Services Endangered Species Conservation, Recovery, and Proactive Strategies Energy Human Dimensions Invasive Species Landscape Ecology Species of Greatest Conservation Need Species Population, Habitat, and Harvest Management Wildlife Health and Disease

Circular↗
USGS2018

Characterization and evaluation of controls on post-fire streamflow response across western U.S. watersheds

This research investigates the impact of wildfires on watershed flow regimes, specifically focusing on evaluation of fire events within specified hydroclimatic regions in the western United States, and evaluating the impact of climate and geophysical variables on response. Eighty-two watersheds were identified with at least 10 years of continuous pre-fire daily streamflow records and 5 years of continuous post-fire daily flow records. Percent change in annual runoff ratio, low flows, high flows, peak flows, number of zero flow days, baseflow index, and Richards–Baker flashiness index were calculated for each watershed using pre- and post-fire periods. Independent variables were identified for each watershed and fire event, including topographic, vegetation, climate, burn severity, percent area burned, and soils data. Results show that low flows, high flows, and peak flows increase in the first 2 years following a wildfire and decrease over time. Relative response was used to scale response variables with the respective percent area of watershed burned in order to compare regional differences in watershed response. To account for variability in precipitation events, runoff ratio was used to compare runoff directly to PRISM precipitation estimates. To account for regional differences in climate patterns, watersheds were divided into nine regions, or clusters, through k-means clustering using climate data, and regression models were produced for watersheds grouped by total area burned. Watersheds in Cluster 9 (eastern California, western Nevada, Oregon) demonstrate a small negative response to observed flow regimes after fire. Cluster 8 watersheds (coastal California) display the greatest flow responses, typically within the first year following wildfire. Most other watersheds show a positive mean relative response. In addition, simple regression models show low correlation between percent watershed burned and streamflow response, implying that other watershed factors strongly influence response. Spearman correlation identified NDVI, aridity index, percent of a watershed's precipitation that falls as rain, and slope as being positively correlated with post-fire streamflow response. This metric also suggested a negative correlation between response and the soil erodibility factor, watershed area, and percent low burn severity. Regression models identified only moderate burn severity and watershed area as being consistently positively/negatively correlated, respectively, with response. The random forest model identified only slope and percent area burned as significant watershed parameters controlling response. Results will help inform post-fire runoff management decisions by helping to identify expected changes to flow regimes, as well as facilitate parameterization for model application in burned watersheds.

Hydrology and Earth System Sciences↗
USGS2016

A simple rubric for Stratigraphic Fidelity (β) of paleoenvironmental time series

The Pliocene, specifically the late Pliocene, has been a focus of paleoclimate research formore than 25 years. Synoptic regional and global reconstructions along with high-resolution time-series have produced nuanced conceptual models of paleoenvironmental conditions and enhanced our understanding of climate variability and climate sensitivity from the Late Pliocene, the most recent interval of global warmth similar to what is projected for the end of the 21st century. These data are used as a source of boundary conditions for climate models as well as ameans of verification of global climate model experiments. In this note, we introduce a measure of stratigraphic fidelity, ß, used to characterize the chronology and achievable resolution of an ever-growing library of Pliocene paleoenvironmental time-series. The ß index serves as an aid to end-users by allowing selection of time-series that meet the stratigraphic requirements of a particular study.

Stratigraphy↗