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

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At least 793 records · Page 44Linked to original sources
USGS1997

Selected trace metals and organic compounds and bioavailability of selected organic compounds in soils, Hackberry Flat, Tillman County, Oklahoma, 1994-95

In 1995 the Oklahoma Department of Wildlife Conservation acquired a drained wetland in southwest Oklahoma known as Hackberry Flat. Following restoration by Wildlife Conservation the wetland will be used by migratory birds and waterfowl. If naturally occurring trace metals and residual organic compounds from agriculture and industry were present, they may have posed a potential biohazard and were a concern for Wildlife Conservation. The U. S. Geological Survey, in cooperation with Wildlife Conservation and the Oklahoma Geological Survey, examined the soils of Hackberry Flat to determine trace metal concentrations, presence of selected organic compounds, and the bioavailability of selected organic compounds in the soils. The purpose of this report is to present the data that establish the baseline concentrations of selected trace metals and organic compounds in the soils of Hackberry Flat prior to wetland restoration. Sampling and analysis were performed using two approaches. One was to collect soil samples and analyze the composition with standard laboratory practices. The second exposed composite soils samples to organic-free water and a semipermeable membrane device that mimics an organism and then analyzed the device. Ten soil samples were collected in 1994 to be analyzed for trace metals, organochlorine pesticides, and polychlorinated biphenyls. Soil samples tested for bioavailability of selected organic compounds were collected in 1995. Most of the 182 soil samples collected were from the center of every 40-acre quarter-quarter section owned by the Wildlife Conservation. The samples were grouped by geographical area with a maximum of 16 sample sites per group. Concentrations of most selected trace metals measured from soils in Hackberry Flat are within the range of mean concentrations measured in cultivated soils within the United States. Organochlorine pesticides, polychlorinated biphenyls, and polyaromatic hydrocarbons were not found at concentrations above the analytical detection levels and, if present, in the soil samples are at concentrations below the detection level of the analytical method used. Organochlorine pesticides, total polychlorinated biphenyls, and polyaromatic hydrocarbons were not detected in any of the semipermeable membrane devices at the analytical detection levels.

Oklahoma↗
USGS2013

Carnivore use of avocado orchards across an agricultural-wildland gradient

Wide-ranging species cannot persist in reserves alone. Consequently, there is growing interest in the conservation value of agricultural lands that separate or buffer natural areas. The value of agricultural lands for wildlife habitat and connectivity varies as a function of the crop type and landscape context, and quantifying these differences will improve our ability to manage these lands more effectively for animals. In southern California, many species are present in avocado orchards, including mammalian carnivores. We examined occupancy of avocado orchards by mammalian carnivores across agricultural-wildland gradients in southern California with motion-activated cameras. More carnivore species were detected with cameras in orchards than in wildland sites, and for bobcats and gray foxes, orchards were associated with higher occupancy rates. Our results demonstrate that agricultural lands have potential to contribute to conservation by providing habitat or facilitating landscape connectivity.

California↗
USGS2002

Historic fire regime in southern California shrublands

Historical variability in fire regime is a conservative indicator of ecosystem sustainability, and thus understanding the natural role of fire in chaparral ecosystems is necessary for proper fire management. It has been suggested that the “natural” fire regime was one of frequent small fires that fragmented the landscape into a fine-grained mixture of age classes that precluded large, catastrophic fires. Some researchers claim that this regime was lost because of highly effective fire suppression and conclude that if fire managers could “restore” a regime of frequent fires with widespread prescription burning, they could eliminate the hazard of catastrophic fires. The primary evidence in support of this model is a study that compared contemporary burning patterns in southern California, U.S.A., a region subject to fire suppression, with patterns in northern Baja California, Mexico, where there is less effective fire suppression. We found that differences in fire regime between these two regions are inconclusive and could not be ascribed conclusively to differences in fire suppression. Historical records suggest that the natural fire regime in southern California shrublands was rather coarse-grained and not substantively different from the contemporary regime. There is no evidence that fire-management policies have created the contemporary fire regime dominated by massive Santa Ana wind-driven fires. Increased expenditures on fire suppression and increased loss of property and lives are the result of human demographic patterns that place increasing demand on fire-suppression forces.

Baja California, California↗
USGS2012

Are all intertidal wetlands naturally created equal? Bottlenecks, thresholds and knowledge gaps to mangrove and saltmarsh ecosystems

Intertidal wetlands such as saltmarshes and mangroves provide numerous important ecological functions, though they are in rapid and global decline. To better conserve and restore these wetland ecosystems, we need an understanding of the fundamental natural bottlenecks and thresholds to their establishment and long-term ecological maintenance. Despite inhabiting similar intertidal positions, the biological traits of these systems differ markedly in structure, phenology, life history, phylogeny and dispersal, suggesting large differences in biophysical interactions. By providing the first systematic comparison between saltmarshes and mangroves, we unravel how the interplay between species-specific life-history traits, biophysical interactions and biogeomorphological feedback processes determine where, when and what wetland can establish, the thresholds to long-term ecosystem stability, and constraints to genetic connectivity between intertidal wetland populations at the landscape level. To understand these process interactions, research into the constraints to wetland development, and biological adaptations to overcome these critical bottlenecks and thresholds requires a truly interdisciplinary approach.

Biological Reviews↗
USGS2018

Novel landscape elements within natural gas fields increase densities but not fitness of an important songbird nest predator

Identifying the elements within human-altered landscapes most associated with population and community changes is critical for conservation and management of sensitive species. We investigated which features of habitat change from natural gas development best explained the density of deer mice ( Peromyscus maniculatus ), an important nest predator of declining sagebrush-obligate songbirds. During 2014–2016, we quantified the spatial extent of habitat change (well pads, roads, and reclaimed areas [i.e., reseeded soils]) surrounding 12 sites spanning two natural gas fields in Wyoming, USA. We further tested whether the altered plant communities within reclaimed areas provided benefits to deer mice, by assessing multiple fitness indices. Deer mouse density increased with surrounding reclaimed area. Powder tracking and dietary analyses confirmed that mice moved through and consumed plant species found exclusively within reclaimed areas. Concomitant fitness metrics of mice, however, were neutrally or negatively related to the amount of surrounding reclaimed area. Mice therefore did not derive any apparent fitness benefits associated with living near reclaimed areas, despite the presence of novel food resources, indicating that increased abundance may be a product of mice dispersing toward reseeded soils. Our study contributes mechanistic insights into the complexities of how human-induced changes to landscapes can influence community dynamics. Minimizing total habitat disturbed during construction, expediting reclamation practices, and using only native and regionally-local seed mixes would likely help minimize increases in synanthropic rodent predators within energy fields. More efficient restoration of disturbed habitat, moreover, may help ameliorate altered predator-prey relationships that affect the success of sensitive species.

Wyoming↗
USGS2018

Evaluating the conservation potential of tributaries for native fishes in the Upper Colorado River Basin

We explored the conservation potential of tributaries in the upper Colorado River basin by modeling native fish species richness as a function of river discharge, temperature, barrier‐free length, and distance to nearest free‐flowing main‐stem section. We investigated a historic period prior to large‐scale water development and a contemporary period. In the historic period, species richness was log‐linearly correlated to variables capturing flow magnitude, particularly mean annual discharge. In the contemporary period, the log‐linear relationship between discharge and species richness was still evident but weaker. Tributaries with lower average temperature and separated from free‐flowing main‐stem sections often had fewer native species compared to tributaries with similar discharge but with warmer temperature and directly connected to free‐flowing main stems. Thus, tributaries containing only a small proportion of main‐stem discharge, especially those at lower elevations with warmer temperatures and connected to free‐flowing main stems, can support a relatively high species richness. Tributaries can help maintain viable populations by providing ecological processes disrupted on large regulated rivers, such as natural flow and temperature regimes, and may present unique conservation opportunities. Efforts to improve fish passage, secure environmental flows, and restore habitat in these tributaries could greatly contribute to conservation of native fish richness throughout the watershed.

Upper Colorado River Basin↗
USGS2016

Governance principles for wildlife conservation in the 21st century

Wildlife conservation is losing ground in the U.S. for many reasons. The net effect is declines in species and habitat. To address this trend, the wildlife conservation institution (i.e., all customs, practices, organizations and agencies, policies, and laws with respect to wildlife) must adapt to contemporary social–ecological conditions. Adaptation could be supported by clear guidelines reflecting contemporary expectations for wildlife governance. We combine elements of public trust thinking and good governance to produce a broad set of wildlife governance principles. These principles represent guidance for ecologically and socially responsible wildlife conservation. They address persistent, systemic problems and, if adopted, will bring the institution into line with modern expectations for governance of public natural resources. Implementation will require changes in values, objectives, and processes of the wildlife conservation institution. These changes may be difficult, but promise improved wildlife conservation outcomes and increased support for conservation. We introduce challenges and opportunities associated with the principles, and encourage dialogue about them among scientists, practitioners, and other leaders in U.S. wildlife conservation. The principles alone will not change the course of conservation for the better, but may be necessary for such change to occur.

Conservation Letters↗
USGS2015

Determining climate change management priorities: A case study from Wisconsin

A burgeoning dialogue exists regarding how to allocate resources to maximize the likelihood of long-term biodiversity conservation within the context of climate change. To make effective decisions in natural resource management, an iterative, collaborative, and learning-based decision process may be more successful than a strictly consultative approach. One important, early step in a decision process is to identify priority species or systems. Although this promotes the conservation of select species or systems, it may inadvertently alter the future of non-target species and systems. We describe a process to screen terrestrial wildlife for potential sensitivity to climate change and then use the results to engage natural resource professionals in a process of identifying priorities for monitoring, research, and adaptation strategy implementation. We demonstrate this approach using a case study from Wisconsin. In Wisconsin, experts identified 23 out of 353 species with sufficient empirical research and management understanding to inform targeted action. Habitat management and management of hydrological conditions were the common strategies for targeted action. Although there may be an interest in adaptation strategy implementation for many species and systems, experts considered existing information inadequate to inform targeted action. According to experts, 40% of the vertebrate species in Wisconsin will require near-term intervention for climate adaptation. These results will inform state-wide conservation planning as well as regional efforts.

Wisconsin↗
USGS2012

Conservation implications when the nest predators are known

Conservation and management of passerines has largely focused on habitat manipulation or restoration because the natural communities on which these birds depend have been destroyed and fragmented. However, productivity is another important aspect of avian conservation, and nest predation can be a large source of nesting mortality for passerines. Recent studies using video surveillance to identify nest predators allow researchers to start evaluating what methods could be used to mitigate nest predation to help passerines of conservation concern. From recent studies, we identified latitudinal and habitat-related patterns in the importance of predator groups that depredate passerine nests. We then reviewed how knowledge of specific nest predators can benefit conservation of bird species of concern. Mammals were the dominant predator group in northern grasslands. Snakes were the dominant predator group in southern habitats. Fire ants were only a nest predator in southern latitudes. Differences in the importance of predator species or groups were likely the result of both their geographic patterns of distribution and habitat preferences. Some direct and indirect predator control measures developed for waterfowl management potentially could be used to benefit passerine productivity. We reviewed three examples-cowbirds, snakes in shrublands, and ground squirrels in grasslands-to illustrate how different predator control strategies may be needed in different situations. Mitigation of passerine nest predation will need to be based on knowledge of predator communities to be effective. This requires large samples of predation events with identified predators; video technology is essential for this task.

Studies in Avian Biology↗
USGS2000

Heron conservation

Herons are large, popular and, in many cases, spectacular birds found in wetlands world-wide, both tropical and temperate, natural and man-made. Some populations are very small and localized, some have decreased, some have expanded their ranges, and a few are pests of human activities. In the fifteen years since the publication of the latest monographic treatment of the family, The Herons Handbook, there has been a tremendous increase in our knowledge of heron status and conservation requirements, set against a backdrop of increasing concern about the future of the world?s wetland habitats. This book provides a comprehensive update following two distinct threads. The status and conservation needs of herons are first presented on a regional basis, in a series of chapters set at a continental or subcontinental scale. Over 200 biologists and heron conservationists have contributed to the data summarized here, and the very latest census and survey results provide the most up-to-date and detailed picture of heron populations currently available. Chapters discussing several critical issues in heron conservation follow, tending to focus on the international nature of the problems.

Book↗
USGS2017

Patterns and magnitude of flow alteration in California, USA

Quantifying the natural flow regime is essential for management of water resources and conservation of aquatic ecosystems. Understanding the degree to which anthropogenic activities have altered flows is critical for developing effective conservation strategies. Assessing flow alteration requires estimates of flows expected in the absence of human influence and under current land use and water management. There are several techniques to predict flows in streams and rivers; however, none have been applied to make predictions of natural flow conditions over large regions and time periods. We utilised machine learning statistical models to predict natural monthly flows (natural streamflows without the influence of water management or anthropogenic land use) in California from 1950 to 2015, using time-dependent and fixed watershed variables from reference stream gages. These models were then used to make estimates of mean, maximum and minimum monthly flows in all streams in the state. We compared observed flows measured at 540 stream gages across the state with expected natural flows at the same locations, to quantify the type, frequency and magnitude of flow alteration over the past 20 years (1996–2015). A gage was considered altered if an observed flow metric (monthly mean, annual maximum, annual minimum) fell outside the 80% prediction interval of the modelled flow estimate. We found that 95% of the 540 stream gages in California had at least 1 month of altered flows over the past 20 years, and 11% of gages were frequently altered (over two-thirds of the months recorded had evidence of altered flows). The type of alteration varied across the state with flows being either depleted, inflated or a mix of both at different times of the year. Most altered gages (68%) exhibited both depletion and inflation in monthly flows over the time period. Inflation of monthly mean flows was most prevalent during the summer months, while depletion of monthly flows was evident throughout the year. Type, frequency and magnitude of flow alteration varied by region. Flow depletion was present at >80% of gages in the North Coast and Central Coast, flow inflation was measured at >80% of gages in the South Coast and San Francisco Bay and both depletion and inflation were evident at >80% of gages in the Sacramento River and San Joaquin and Tulare regions. Annual maximum flows were consistently depleted and annual minimum flows were commonly inflated in the Sierra Nevada and Central Valley (Sacramento River and San Joaquin and Tulare regions). This is the first study to comprehensively assess flow alteration at stream gages across California. Understanding the patterns and degree of alteration can aid in prioritising streams for environmental flow assessment and developing conservation strategies for native freshwater biota.

California↗
USGS2014

How much land is needed for feral pig hunting in Hawai'i?

Hunting is often considered to be incompatible with conservation of native biota and watershed functions in Hawai'i. Management actions for conservation generally exclude large non-native mammals from natural areas, thereby reducing the amount of land area available for hunting activities and the maintenance of sustainable game populations. An approach which may be useful in addressing the necessary minimum amount of land area allocated for hunting in Hawai'i is to determine the amount of land area necessary for sustaining populations of hunted animals to meet current levels harvested by the public. We ask: What is the total amount of land necessary to provide sustained-yield hunting of game meat for food at the current harvest level on Hawai'i Island if only feral pigs (Sus scrofa) were to be harvested? We used a simplistic analysis to estimate that 1 317.6 km2-1 651.4 km2 would be necessary to produce 187 333.6 kg of feral pig meat annually based on the range of dressed weight per whole pig, the proportion of a pig population that can be sustainably removed annually, and the density of pig populations in the wild. This amount of area comprises 12.6-15.8% of the total land area of Hawai'i Island, but more likely represents 27.6-43.5% of areas that may be compatible with sustained-yield hunting.

Hawai'i↗
USGS2018

Broad‐scale occurrence of a subsidized avian predator: reducing impacts of ravens on sage‐grouse and other sensitive prey

Expanding human enterprise across remote environments impacts numerous wildlife species. Anthropogenic resources provide subsidies for generalist predators that can lead to cascading effects on prey species at lower trophic levels. A fundamental challenge for applied ecologists is to disentangle natural and anthropogenic influences on species occurrence, and subsequently develop spatially explicit models to help inform management and conservation decisions. Using Bayesian hierarchical occupancy models, we mapped the broad‐scale occurrence of common ravens Corvus corax as a function of natural and anthropogenic landscape covariates using >15,000 point count surveys performed during 2007–2016 within the Great Basin region, USA. Raven abundance and distribution is substantially increasing across the American west due to unintended anthropogenic resource subsidies. Importantly, ravens prey on eggs and chicks of numerous species including greater sage‐grouse Centrocercus urophasianus , an indicator species whose decline is at the centre of national conservation strategies and land use policies.Anthropogenic factors that contributed to greater raven occurrence were: increased road density, presence of transmission lines, agricultural activity, and presence of roadside rest areas. Natural landscape characteristics included lower elevations with greener vegetation (NDVI), greater stream and habitat edge densities, and lower percentages of big sagebrush A. tridentata spp . Interactions between anthropogenic sources of nesting substrate and food subsidies suggested that raven occurrence increased multiplicatively when these resource subsidies co‐occurred. Overall, the average probability of raven occurrence estimated within sagebrush ecosystems of the study area was ~0.83. Synthesis and applications . We demonstrate how anthropogenic factors can be disentangled from natural effects when making spatially‐explicit predictions of subsidized predators occurring across expansive landscapes. This approach can guide management decisions where subsidized predators overlap sensitive prey habitats. For example, we identify areas where elevated raven occurrence coincides with breeding sage‐grouse concentration areas and appears to be largely driven by anthropogenic factors. Management applications could focus on reducing raven access to anthropogenic subsidies in these areas, while prioritizing habitat improvements for sage‐grouse elsewhere. Our approach is applicable to other species where widespread survey data are available.

Journal of Applied Ecology↗
USGS2018

The natural capital accounting opportunity: Let's really do the numbers

The nation’s economic accounts provide objective, regular, and standardized information routinely relied upon by public and private decision makers. But they are incomplete. The U.S. and many other nations currently do not account for the natural capital — such as the wildlife, forests, grasslands, soils, and water bodies—upon which all other economic activity rests. By creating formal natural capital accounts (NCA) and ecosystem goods and services (EGS) accounts, governments and businesses can better understand the past, peer into the future, innovate, conserve, and plan for environmental shocks. They would standardize, regularly repeat, and aggregate diverse natural resource, environmental, and social and economic data and could thereby play a significant role in advancing the science of coupled biophysical and social systems.

BioScience↗
USGS1998

Impact of alternative regeneration methods on genetic diversity in coastal Douglas-fir

Genetic implications of natural and artificial regeneration following three regeneration methods (group selection, shelterwood, and clearcut) were investigated in coastal Douglas-fir ( Pseudotsuga menziesii var. menziesii [Mirb.] Franco) using genetic markers (17 allozyme loci). In general, harvesting followed by either natural or artificial regeneration resulted in offspring populations little altered from those in the previous generation. Cutting the smallest trees to form shelterwoods, however, resulted in the removal of rare, presumably deleterious, alleles, such that slightly fewer alleles per locus were observed among residual trees (2.76) and natural regeneration (2.75) than found in uncut (control) stands (2.86). Thus, although the shelterwood regime appears quite compatible with gene conservation, it would be best to leave parent trees of a range of sizes in shelterwoods designated as gene conservation reserves, in order to maximize the number of alleles (regardless of current adaptive value) in naturally regenerated offspring. Seedling stocks used for artificial regeneration in clearcut, shelterwood, and group selection stands (7 total) had significantly greater levels of genetic diversity, on average, than found in natural regeneration. This is probably because the seeds used in artificial seedling stocks came from many wild stands and thus, sampled more diversity than found in single populations. For. Sci. 44(3): 390-396.

Forest Science↗
USGS2022

Forbs included in conservation seed mixes exhibit variable blooming detection rates and cost-effectiveness: Implications for pollinator habitat design

Although forb-rich plantings for pollinator habitat are becoming more common, natural resource managers lack insight on the cost-effectiveness of forbs seeded in private land conservation programs. Additional information on the possible benefits of including more forb species in a mix may help guide the design of future pollinator habitat. We examined the detection of blooming forbs from seed mixes, colonization of non-seeded blooming forbs, and bee utilization of forbs on private lands enrolled in United States Department of Agriculture (USDA) conservation programs. By obtaining the original seed mixes used on conservation program lands and sampling forbs and bees, we provide a first-hand evaluation of the cost-effectiveness of USDA conservation plantings in a field setting. We identified seeded forbs with the highest blooming detection rates and the most common colonizing forbs across 27 sites, the majority of which were considered young conservation plantings. We additionally designated 16 forbs as the most cost-effective due to their higher-than-average blooming detection rate and lower-than-average seed cost. We found a positive association between seed mix richness and number of blooming, seeded forbs detected and found a negative association with blooming, non-native colonizing forbs, which highlights potential benefits of increasing forb richness in seed mixes. However, we did not observe an association between seed mix richness and wild bee or honey bee counts. Examining the cost-effectiveness of seeded forbs on USDA conservation enrollments and subsequent bee utilization can inform land managers in designing seed mixes for pollinator habitat.

Restoration Ecology↗
USGS2011

Resolving structural uncertainty in natural resources management using POMDP approaches

In recent years there has been a growing focus on the uncertainties of natural resources management, and the importance of accounting for uncertainty in assessing management effectiveness. This paper focuses on uncertainty in resource management in terms of discrete-state Markov decision processes (MDP) under structural uncertainty and partial observability. It describes the treatment of structural uncertainty with approaches developed for partially observable resource systems. In particular, I show how value iteration for partially observable MDPs (POMDP) can be extended to structurally uncertain MDPs. A key difference between these process classes is that structurally uncertain MDPs require the tracking of system state as well as a probability structure for the structure uncertainty, whereas with POMDPs require only a probability structure for the observation uncertainty. The added complexity of the optimization problem under structural uncertainty is compensated by reduced dimensionality in the search for optimal strategy. A solution algorithm for structurally uncertain processes is outlined for a simple example in conservation biology. By building on the conceptual framework developed for POMDPs, natural resource analysts and decision makers who confront structural uncertainties in natural resources can take advantage of the rapid growth in POMDP methods and approaches, and thereby produce better conservation strategies over a larger class of resource problems.

Ecological Modelling↗
USGS1976

Nature . . . an environmental yardstick

To one who has spent his professional career in geologic science, conservation always has had special meaning. In the measurements so necessary to his work the geologist develops an integrity in the use of numbers and in the qualifications attending the validity of numbers. Scientific analysis of geologic events and sequence develops a keen sense of what is coincidental, correlative, and consequential. The geologist applies his science in evaluating hazards to man as natural catastrophes and/or benefits to man such as earth materials that form the resource base of his society. But more than these the geologist has acquired a deep appreciation for the planet as a whole, its inner structure, its landscape, and the living things that abound.

Information and Technology Report↗