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At least 145 records · Page 8Linked to original sources

USGS2011

Compilation of watershed models for tributaries to the Great Lakes, United States, as of 2010, and identification of watersheds for future modeling for the Great Lakes Restoration Initiative

As part of the Great Lakes Restoration Initiative (GLRI) during 2009–10, the U.S. Geological Survey (USGS) compiled a list of existing watershed models that had been created for tributaries within the United States that drain to the Great Lakes. Established Federal programs that are overseen by the National Oceanic and Atmospheric Administration (NOAA) and the U.S. Army Corps of Engineers (USACE) are responsible for most of the existing watershed models for specific tributaries. The NOAA Great Lakes Environmental Research Laboratory (GLERL) uses the Large Basin Runoff Model to provide data for the management of water levels in the Great Lakes by estimating United States and Canadian inflows to the Great Lakes from 121 large watersheds. GLERL also simulates streamflows in 34 U.S. watersheds by a grid-based model, the Distributed Large Basin Runoff Model. The NOAA National Weather Service uses the Sacramento Soil Moisture Accounting model to predict flows at river forecast sites. The USACE created or funded the creation of models for at least 30 tributaries to the Great Lakes to better understand sediment erosion, transport, and aggradation processes that affect Federal navigation channels and harbors. Many of the USACE hydrologic models have been coupled with hydrodynamic and sediment-transport models that simulate the processes in the stream and harbor near the mouth of the modeled tributary. Some models either have been applied or have the capability of being applied across the entire Great Lakes Basin; they are (1) the SPAtially Referenced Regressions On Watershed attributes (SPARROW) model, which was developed by the USGS; (2) the High Impact Targeting (HIT) and Digital Watershed models, which were developed by the Institute of Water Research at Michigan State University; (3) the Long-Term Hydrologic Impact Assessment (L–THIA) model, which was developed by researchers at Purdue University; and (4) the Water Erosion Prediction Project (WEPP) model, which was developed by the National Soil Erosion Research Laboratory of the U.S. Department of Agriculture. During 2010, the USGS used the Precipitation-Runoff Modeling System (PRMS) to create a hydrologic model for the Lake Michigan Basin to assess the probable effects of climate change on future groundwater and surface-water resources. The Water Availability Tool for Environmental Resources (WATER) model and the Analysis of Flows In Networks of CHannels (AFINCH) program also were used to support USGS GLRI projects that required estimates of streamflows throughout the Great Lakes Basin. This information on existing watershed models, along with an assessment of geologic, soils, and land-use data across the Great Lakes Basin and the identification of problems that exist in selected tributary watersheds that could be addressed by a watershed model, was used to identify three watersheds in the Great Lakes Basin for future modeling by the USGS. These watersheds are the Kalamazoo River Basin in Michigan, the Tonawanda Creek Basin in New York, and the Bad River Basin in Wisconsin. These candidate watersheds have hydrogeologic, land-type, and soil characteristics that make them distinct from each other, but that are representative of other tributary watersheds within the Great Lakes Basin. These similarities in the characteristics among nearby watersheds will enhance the usefulness of a model by improving the likelihood that parameter values from a previously modeled watershed could reliably be used in the creation of a model of another watershed in the same region. The software program Hydrological Simulation Program–Fortran (HSPF) was selected to simulate the hydrologic, sedimentary, and water-quality processes in these selected watersheds. HSPF is a versatile, process-based, continuous-simulation model that has been used extensively by the scientific community, has the ongoing technical support of the U.S. Environmental Protection Agency and USGS, and provides a means to evaluate the effects that land-use changes or management practices might have on the simulated processes.

Great Lakes Basin↗

USGS2011

Functional profiles reveal unique ecological roles of various biological soil crust organisms

At the heart of the body of research on biodiversity effects on ecosystem function is the debate over whether different species tend to be functionally singular or redundant. When we consider ecosystem multi‐function, the provision of multiple ecosystem functions simultaneously, we may find that seemingly redundant species may in fact play unique roles in ecosystems. 2. Over the last few decades, the significance of biological soil crusts (BSCs) as ecological boundaries and ecosystem engineers, and their multi‐functional nature, has become increasingly well documented. We compiled ‘functional profiles’ of the organisms in this understudied community, to determine whether functional singularity emerges when multiple ecosystem functions are considered. 3. In two data sets, one representing multiple sites around the semi‐arid regions of Spain (regional scale), and another from a single site in central Spain (local scale), we examined correlations between the abundance or frequency of BSC species in a community, and multiple surrogates of ecosystem functioning. There was a wide array of apparent effects of species on specific functions. 4. Notably, in gypsiferous soils and at regional scale, we found that indicators of carbon (C) and phosphorus cycling were apparently suppressed and promoted by the lichens Diploschistes diacapsis and Squamarina lentigera , respectively. The moss Pleurochaete squarrosa appears to promote C cycling in calcareous soils at this spatial scale. At the local scale in gypsiferous soils, D. diacapsis positively correlated with carbon cycling, but negatively with nitrogen cycling, whereas numerous lichens exhibited the opposite profile. 5. We found a high degree of functional singularity, i.e. that species were highly individualistic in their effects on multiple functions. Many functional attributes were not easily predictable from existing functional grouping systems based primarily on morphology. 6. Our results suggest that maintaining species‐rich BSC communities is crucial to maintain the overall functionality of ecosystems dominated by these organisms, and that dominance and the outcome of competition could be highly influential in the determination of such functionality.

Functional Ecology↗

USGS2009

The influence of use-related, environmental, and managerial factors on soil loss from recreational trails

Recreational uses of unsurfaced trails inevitably result in their degradation, with the type and extent of resource impact influenced by factors such as soil texture, topography, climate, trail design and maintenance, and type and amount of use. Of particular concern, the loss of soil through erosion is generally considered a significant and irreversible form of trail impact. This research investigated the influence of several use-related, environmental, and managerial factors on soil loss on recreational trails and roads at Big South Fork National River and Recreation Area, a unit of the U.S. National Park Service. Regression modeling revealed that trail position, trail slope alignment angle, grade, water drainage, and type of use are significant determinants of soil loss. The introduction of individual and groups of variables into a series of regression models provides improved understanding and insights regarding the relative influence of these variables, informing the selection of more effective trail management actions. Study results suggest that trail erosion can be minimized by avoiding “fall-line” alignments, steep grades, and valley-bottom alignments near streams, installing and maintaining adequate densities of tread drainage features, applying gravel to harden treads, and reducing horse and all-terrain vehicle use or restricting them to more resistant routes. This research also sought to develop a more efficient Variable Cross-Sectional Area method for assessing soil loss on trails. This method permitted incorporation of CSA measures in a representative sampling scheme applied to a large (24%) sample of the park's 526 km trail system. The variety of soil loss measures derived from the Variable CSA method, including extrapolated trail-wide soil loss estimates, permit an objective quantification of soil erosion on recreational trails and roads. Such data support relational analyses to increase understanding of trail degradation, and long-term monitoring of the natural and recreational integrity of the trail system infrastructure.

Journal of Environmental Management↗

USGS2004

The effect of fire on mercury cycling in the soils of forested watersheds: Acadia National Park, Maine, U.S.A

This study compares mercury (Hg) and methylmercury (MeHg) distribution in the soils of two forested stream watersheds at Acadia National Park, Maine, U.S.A. Cadillac Brook watershed, which burned in 1947, has thin soils and predominantly deciduous vegetation. It was compared to the unburned Hadlock Brook watershed, with thicker soil and predominantly coniferous vegetation. Soils in both watersheds were primarily well drained. The fire had a significant impact on the Cadillac watershed, by raising the soil pH, altering the vegetation, and reducing carbon and Hg pools. Total Hg content was significantly higher (P < 0.05) in Hadlock soils (0.18 kg Hg ha-1) compared to Cadillac soils (0. 13 kg Hg ha-1). Hadlock O horizon had an average Hg concentration of 134??48 ng Hg g-1 dry weight, compared to 103??23 ng Hg g-1 dry weight in Cadillac O horizon. Soil pH was significantly higher in all soil horizons at Cadillac compared to Hadlock soils. This difference was especially significant in the O horizon, where Cadillac soils had an average pH of 3.41??0.22 compared to Hadlock soils with an average pH of 2.99??0.13. To study the mobilization potential of Hg in the O horizons of the two watersheds, batch adsorption experiments were conducted, and the results were modeled using surface complexation modeling. The results of Hg adsorption experiments indicated that the dissolved Hg concentration was controlled by the dissolved organic carbon (DOC) concentration. The adsorption isotherms suggest that Hg is more mobile in the O horizon of the unburned Hadlock watershed because of higher solubility of organic carbon resulting in higher DOC concentrations in that watershed. Methylmercury concentrations, however, were consistently higher in the burned Cadillac O horizon (0.20??0.13 ng Hg g-1 dry weight) than in the unburned Hadlock O horizon (0.07??0.07 ng Hg g-1 dry weight). Similarly, Cadillac soils possessed a higher MeHg content (0.30 g MeHg ha-1) than Hadlock soils (0.16 g MeHg ha-1). The higher MeHg concentrations in Cadillac soils may reflect generally faster rates of microbial metabolism due to more rapid nutrient cycling and higher soil pH in the deciduous forest. In this research, we have shown that the amount of MeHg is not a function of the total pool of Hg in the watershed. Indeed, MeHg was inversely proportional to total Hg, suggesting that landscape factors such as soil pH, vegetation type, or land use history (e.g., fire) may be the determining factors for susceptibility to high Hg in biota. ?? 2004 Kluwer Academic Publisher. Printed in the Netherlands.

Water, Air, & Soil Pollution↗

USGS2016

Trace elements in stormflow, ash, and burned soil following the 2009 station fire in southern California

Most research on the effects of wildfires on stream water quality has focused on suspended sediment and nutrients in streams and water bodies, and relatively little research has examined the effects of wildfires on trace elements. The purpose of this study was two-fold: 1) to determine the effect of the 2009 Station Fire in the Angeles National Forest northeast of Los Angeles, CA on trace element concentrations in streams, and 2) compare trace elements in post-fire stormflow water quality to criteria for aquatic life to determine if trace elements reached concentrations that can harm aquatic life. Pre-storm and stormflow water-quality samples were collected in streams located inside and outside of the burn area of the Station Fire. Ash and burned soil samples were collected from several locations within the perimeter of the Station Fire. Filtered concentrations of Fe, Mn, and Hg and total concentrations of most trace elements in storm samples were elevated as a result of the Station Fire. In contrast, filtered concentrations of Cu, Pb, Ni, and Se and total concentrations of Cu were elevated primarily due to storms and not the Station Fire. Total concentrations of Se and Zn were elevated as a result of both storms and the Station Fire. Suspended sediment in stormflows following the Station Fire was an important transport mechanism for trace elements. Cu, Pb, and Zn primarily originate from ash in the suspended sediment. Fe primarily originates from burned soil in the suspended sediment. As, Mn, and Ni originate from both ash and burned soil. Filtered concentrations of trace elements in stormwater samples affected by the Station Fire did not reach levels that were greater than criteria established for aquatic life. Total concentrations for Fe, Pb, Ni, and Zn were detected at concentrations above criteria established for aquatic life.

California↗

USGS2016

Can the eastern red-backed salamander (Plethodon cinereus) persist in an acidified landscape?

Hardwood forests of eastern North America have experienced decades of acidic deposition, leading to soil acidification where base cation supply was insufficient to neutralize acid inputs. Negative impacts of soil acidity on amphibians include disrupted embryonic development, lower growth rates, and habitat loss. However, some amphibians exhibit intraspecific variation in acid tolerance, suggesting the potential for local adaptation in areas where soils are naturally acidic. The eastern red-backed salamander ( Plethodon cinereus ) is a highly abundant top predator of the northern hardwood forest floor. Early research found that P. cinereus was sensitive to acidic soils, avoiding substrates with pH < 3.8 and experiencing decreased growth rates in acidic habitats. However, recent studies have documented P. cinereus populations in lower pH conditions than previously observed, suggesting some populations may persist in acidic conditions. Here, we evaluated relationships between organic horizon soil pH and P. cinereus abundance, adult health (body size and condition), and microhabitat selection, based on surveys of 34 hardwood forests in northeastern United States that encompass a regional soil pH gradient. We found no associations between soil pH and P. cinereus abundance or health, and observed that this salamander used substrates with pH similar to that available, suggesting that pH does not mediate their fine-scale distributions. The strongest negative predictor of P. cinereus abundance was the presence of dusky salamanders ( Desmognathus spp.), which were most abundant in the western Adirondacks. Our results indicate that P. cinereus occupies a wider range of soil pH than has been previously thought, which has implications for their functional role in forest food webs and nutrient cycles in acid-impaired ecosystems. Tolerance of P. cinereus for more acidic habitats, including anthropogenically acidified forests, may be due to local adaptation in reproductively isolated populations and/or generalist life history traits that allow them to exploit a wider resource niche.

Ecosphere↗

USGS1998

Tracing solute mobility at the Panola Mountain Research Watershed, Georgia, USA: Variations in Na+, Cl-, and H4SiO4 concentrations

Concentration variations of sodium (N+). chloride (Cl-). and dissolved silica (H4SiO4) in rainfall, throughfall, soil water, groundwater and streamwater were evaluated at the Panola Mountain Research Watershed near Atlanta, Georgia, to determine how variations in concentrations of these solutes provide greater understanding of water quality evolution at the hillslope and catchment scales Stormwater moves rapidly to depth along preferred pathways in a deciduous forest hillslope, but the composition of the mobile unsaturated zone water in the hillslope is not reflected in compositional variations of streamwater during rainstorms. The Na+, Cl-, and H4SiO4 concentrations behave similarly in streamwater, decreasing with increasing discharge and increasing with water residence time. Consequently, the lowest flows are associated with the highest concentrations and the oldest water. Streamwater composition is most similar to groundwater and stormflow variations reflect a dilution of groundwater. Subtle differences in the relations among solute concentrations and discharge reflect different sources, especially for Cl-. For example, the residence time of groundwater, as inferred from landscape position, generally is positively related to Na+ and H4SiO4 concentrations, but not to Cl- concentrations. The Na+ and H4SiO4 are derived from mineral weathering and are continuously supplied along hydrological pathways. In contrast, Cl- is derived from atmospheric deposition and is affected only by evapotranspiration (ET) and transport. ET increases Cl- concentrations in matrix soil waters, which are subsequently transported to the saturated zone where Cl- is effectively isolated from further evaporative concentration.

IAHS-AISH Publication↗

USGS1989

Partition and adsorption on soil and mobility of organic pollutants and pesticides

The mechanism for sorption of organic pollutants and pesticides by soil has long been a subject of profound interest because of its direct impacts on the mobility and activity of the compounds in soil. Although a large volume of laboratory and field data on many aspects of soil behavior had been gathered between the 1950s and 1970s, during which period the use of organic pesticides was increased, no general agreement was reached regarding the sorptive mechanism involved. Since the 1970s, the outgrowth of public concern over environmental contamination further stimulated research in this subject. The development of this field of research has now reached a point that the diverse characteristics of soil sorption can be placed in a much better perspective. This enables researchers to reexamine old and new data for consistency and for assessing the activity of organic pollutants and pesticides in soil.

Book chapter↗

USGS1977

Survey of geologic research on Green River oil shale

In the last decade, geologic research on oil-shale deposits and associated rocks of the Green River Formation in Colorado, Utah, and Wyoming has mushroomed largely in response to the Department of the Interior's oil-shale leasing program and to the active interest of private and governmental groups concerned with environmental aspects of an oil-shale industry. Geologic studies, however, are only a small part of the total research effort on Green River oil shale. Investigations covering such diverse topics as archaeology, plant and wildlife, mining and processing, oil-shale law, sociology, and "baseline" studies of soils, water, and air are currently being pursued by researchers from the United States and from as far away as England. Probably noother mineral deposit in the world is being so intensively studied by so many, but it has yet to yield a single barrel of oil commercially.

Colorado, Utah, Wyoming↗

USGS1976

Progress in remote sensing (1972-1976)

This report concerns the progress in remote sensing during the period 1972–1976. Remote sensing has been variously defined but is basically the art or science of telling something about an object without touching it. During the past four years, the major research thrusts have been in three areas: (1) computer-assisted enhancement and interpretation systems; (2) earth science applications of Landsat data; (3) and investigations of the usefulness of observations of luminescence, thermal infrared, and microwave energies. Based on the data sales at the EROS Data Center, the largest users of the Landsat data are industrial companies, followed by government agencies (both national and foreign), and academic institutions. Thermal surveys from aircraft have become largely operational, however, significant research is being undertaken in the field of thermal modeling and analysis of high altitude images. Microwave research is increasing rapidly and programs are being developed for satellite observations. Microwave research is concentrating on oil spill detection, soil moisture measurement, and observations of ice distributions. Luminescence investigations offer promise for becoming a quantitative method of assessing vegetation stress and pollutant concentrations.

Photogrammetria↗

USGS2016

Predicting the occurrence of cave-inhabiting fauna based on features of the earth surface environment

One of the most challenging fauna to study in situ is the obligate cave fauna because of the difficulty of sampling. Cave-limited species display patchy and restricted distributions, but it is often unclear whether the observed distribution is a sampling artifact or a true restriction in range. Further, the drivers of the distribution could be local environmental conditions, such as cave humidity, or they could be associated with surface features that are surrogates for cave conditions. If surface features can be used to predict the distribution of important cave taxa, then conservation management is more easily obtained. We examined the hypothesis that the presence of major faunal groups of cave obligate species could be predicted based on features of the earth surface. Georeferenced records of cave obligate amphipods, crayfish, fish, isopods, beetles, millipedes, pseudoscorpions, spiders, and springtails within the area of Appalachian Landscape Conservation Cooperative in the eastern United States (Illinois to Virginia and New York to Alabama) were assigned to 20 x 20 km grid cells. Habitat suitability for these faunal groups was modeled using logistic regression with twenty predictor variables within each grid cell, such as percent karst, soil features, temperature, precipitation, and elevation. Models successfully predicted the presence of a group greater than 65% of the time (mean = 88%) for the presence of single grid cell endemics, and for all faunal groups except pseudoscorpions. The most common predictor variables were latitude, percent karst, and the standard deviation of the Topographic Position Index (TPI), a measure of landscape rugosity within each grid cell. The overall success of these models points to a number of important connections between the surface and cave environments, and some of these, especially soil features and topographic variability, suggest new research directions. These models should prove to be useful tools in predicting the presence of species in understudied areas.

Appalachian Landscape Conservation Cooperative↗

USGS2001

U.S. Geological Survey programs and investigations related to soil and water conservation

The U.S. Geological Survey has a rich tradition of collecting hydrologic data, especially for fluxes of water and suspended sediment, that provide a foundation for studies of soil and water conservation. Applied and basic research has included investigations of the effects of land use on rangelands, croplands, and forests; hazards mapping; derivation of flood and drought frequency, and other statistics related to streamflow and reservoir storage; development and application of models of rainfall-runoff relations, chemical quality, and sediment movement; and studies of the interactive processes of overland and channel flow with vegetation. Networks of streamgaging stations and (or) sampling sites within numerous drainage basins are yielding information that extends databases and enhances the ability to use those data for interpretive studies.

International Journal of Sediment Research↗

USGS2014

Potential environmental effects of pack stock on meadow ecosystems of the Sierra Nevada, USA

Pack and saddle stock, including, but not limited to domesticated horses, mules, and burros, are used to support commercial, private and administrative activities in the Sierra Nevada. The use of pack stock has become a contentious and litigious issue for land management agencies in the region inter alia due to concerns over effects on the environment. The potential environmental effects of pack stock on Sierra Nevada meadow ecosystems are reviewed and it is concluded that the use of pack stock has the potential to influence the following: (1) water nutrient dynamics, sedimentation, temperature, and microbial pathogen content; (2) soil chemistry, nutrient cycling, soil compaction and hydrology; (3) plant individuals, populations and community dynamics, non-native invasive species, and encroachment of woody species; and (4) wildlife individuals, populations and communities. It is considered from currently available information that management objectives of pack stock should include the following: minimise bare ground, maximise plant cover, maintain species composition of native plants, minimise trampling, especially on wet soils and stream banks, and minimise direct urination and defecation by pack stock into water. However, incomplete documentation of patterns of pack stock use and limited past research limits current understanding of the effects of pack stock, especially their effects on water, soils and wildlife. To improve management of pack stock in this region, research is needed on linking measurable monitoring variables (e.g. plant cover) with environmental relevancy (e.g. soil erosion processes, wildlife habitat use), and identifying specific environmental thresholds of degradation along gradients of pack stock use in Sierra Nevada meadows.

Rangeland Journal↗

USGS2023

Global dataset of soil organic carbon in tidal marshes

Tidal marshes store large amounts of organic carbon in their soils. Field data quantifying soil organic carbon (SOC) stocks provide an important resource for researchers, natural resource managers, and policy-makers working towards the protection, restoration, and valuation of these ecosystems. We collated a global dataset of tidal marsh soil organic carbon (MarSOC) from 99 studies that includes location, soil depth, site name, dry bulk density, SOC, and/or soil organic matter (SOM). The MarSOC dataset includes 17,454 data points from 2,329 unique locations, and 29 countries. We generated a general transfer function for the conversion of SOM to SOC. Using this data we estimated a median (± median absolute deviation) value of 79.2 ± 38.1 Mg SOC ha −1 in the top 30 cm and 231 ± 134 Mg SOC ha −1 in the top 1 m of tidal marsh soils globally. This data can serve as a basis for future work, and may contribute to incorporation of tidal marsh ecosystems into climate change mitigation and adaptation strategies and policies.

Scientific Data↗

USGS1999

NEOCHIM: An electrochemical method for environmental application

Ion migration and electroosmosis are the principal processes underlying electrokinetic remediation of hazardous wastes from soils. These processes are a response of charged species to an applied electrical current and they are accompanied by electrolysis of water at the electrodes through which the current is applied. Electrolysis results in the formation of OH- at the cathode and H+ at the anode. The current drives the OH- and H+ thus formed from the electrodes, through the soil and to the electrode of opposite charge. Introduction of OH- and H+ into the soil being treated modifies soil chemistry and can interfere with either the collection or immobilization of hazardous waste ions. The introduction of either OH- or H+ to the soil can be problematic to electrokinetic remediation but the problem caused by OH- has been the focus of most researchers. The problem has been addressed by flushing the OH- from the soil near the cathode or treating the soil with buffers. These treatments would apply as well to soils affected by H+. With the NEOCHIM technology, developed by the U.S. Geological Survey (USGS) for use as a sampling technique in exploration for buried ore deposits, OH- and H+ are retained in the inner compartment of two-compartment electrodes and are thus prevented from reaching the soil. This enables the extraction of cations and anions, including anionic forms of toxic metals such as HAsO42-. One of the principal attributes of NEOCHIM is the large volume of soil from which ions can be extracted. It is mathematically demonstrable that NEOCHIM extraction volumes can be orders of magnitude greater than volumes typically sampled in more conventional geochemical exploration methods or for environmental sampling. The technology may also be used to introduce selected ions into the soil that affect the solubility of ceratin ions present in the soil. Although field tests for mineral exploration have shown NEOCHIM extraction efficiencies of about 25-35%, laboratory experiments suggest that significantly higher efficiencies are possible. The attributes of NEOCHIM combined with relatively low cost of electrical power, indicate that the technology may be useful for remediation and monitoring of hazardous waste sites. Of particular importance is that NEOCHIM extractions affect only dissolved and electrically charged species, hence those prone to move in groundwater.The U.S. Geological Survey (USGS) has developed a technology called NEOCHIM for use as a sampling technique in exploration for buried deposits. With this technology, OH- and H+ are retained in the inner compartment of two-compartment electrodes and are thus prevented from reaching the soil. This enables the extraction of cations and anions. Laboratory experiments suggest extraction efficiencies higher than 25-35%.

Journal of Geochemical Exploration↗

USGS2006

The potential roles of biological soil crusts in dryland hydrologic cycles

Biological soil crusts (BSCs) are the dominant living cover in many drylands of the world. They possess many features that can influence different aspects of local hydrologic cycles, including soil porosity, absorptivity, roughness, aggregate stability, texture, pore formation, and water retention. The influence of biological soil crusts on these factors depends on their internal and external structure, which varies with climate, soil, and disturbance history. This paper presents the different types of biological soil crusts, discusses how crust type likely influences various aspects of the hydrologic cycle, and reviews what is known and not known about the influence of biological crusts on sediment production and water infiltration versus runoff in various drylands around the world. Most studies examining the effect of biological soil crusts on local hydrology are done by comparing undisturbed sites with those recently disturbed by the researchers. Unfortunately, this greatly complicates interpretation of the results. Applied disturbances alter many soil features such as soil texture, roughness, aggregate stability, physical crusting, porosity, and bulk density in ways that would not necessarily be the same if crusts were not naturally present. Combined, these studies show little agreement on how biological crusts affect water infiltration or runoff. However, when studies are separated by biological crust type and utilize naturally occurring differences among these types, results indicate that biological crusts in hyperarid regions reduce infiltration and increase runoff, have mixed effects in and regions, and increase infiltration and reduce runoff in semiarid cool and cold drylands. However, more studies are needed before broad generalizations can be made on how biological crusts affect infiltration and runoff. We especially need studies that control for sub-surface soil features such as bulk density, micro- and macropores, and biological crust structure. Unlike the mixed effects of biological crusts on infiltration and runoff among regions, almost all studies show that biological crusts reduce sediment production, regardless of crust or dryland type.

Hydrological Processes↗

USGS2005

Animating the biodynamics of soil thickness using process vector analysis: A dynamic denudation approach to soil formation

This paper expands the dynamic denudation framework of landscape evolution by providing new process insights and details on how soil and its signature morphological feature, the biomantle, form and function in the environment. We examine soils and their biomantles from disparate parts of the world, from the tropics through midlatitudes and hyperarid through perhumid, a range that exhibits varying environments for, and of, life. We then explicate the process pathways that cause soils to thicken and thin, and to even disappear, then reform. We do this by examining thickness relationships, where soil thickness stand biomantle thickness bt are functions of upbuilding u and deepening d minus removal r processes, hence st/bt=f(u+d-r). Upbuilding has two subsets, u1, which includes all exogenous (allochthonous-outside) mineral and/or organic inputs to the soil system, and u2, which includes all endogenous (autochthonous-in situ) processes and productions, including weathering. Exogenous u1 inputs include eolian and slopewash inputs (sedimentations) of mineral and organic materials, mass wasting accumulations and the like. Endogenous u2 processes and productions include the sum of in situ bioturbations, biosynthetic productions, organic accumulations, biovoid productions, weathering and volume increases caused by their sum. Endogenous upbuildings, which dominantly occur in the biomantle, are basically biodynamic bd processes and productions, hence u2=bd. Therefore, if exogenous upbuildings u1 are minimal or zero, then biomantle thickness bt is expressed by bt=f(u2-r) or bt=f(bd-r). Drawing on these relationships, we employ a graphic-conceptual device called process vector analysis in a digital animation (see supplementary materials or cf. https://netfiles.uiuc.edu/jdomier/www/temp/ biomantle.html) that illustrates the main pathways that form both Earth's soil and its unique epidermis, the biomantle. We then discuss the main elements of the animation using still frames that represent thickness turning points. We end by encouraging researchers, instructors and students to view Earth's landforms and soils as integrated dynamic entities that are constantly coevolving elements of a global subaerial-subaqueous continuum. ?? 2004 Elsevier B.V. All rights reserved.

Geomorphology↗

USGS1998

Recreation ecology research findings: Implications for wilderness and park managers

Recreationists unintentionally trample vegetation, erode soil, and disturb wildlife. Such human-related impacts present a dilemma for managers charged with the dual objectives of providing recreational opportunities and preserving natural environments. This paper presents some of the principal findings and management implications from research on visitor impacts to protected areas, termed recreation ecology research. This field of study seeks to identify the type and extent of resource impacts and to evaluate relationships between use-related, environmental, and managerial factors. The capabilities and managerial utility of recreation impact monitoring are also described.

Book chapter↗