Filters: Categories: Publication (X) > Types: Journal Citation (X)3,235 results (8ms)
Spatially explicit modeling of 1992–2100 land cover and forest stand age for the conterminous United States
Information on future land-use and land-cover (LULC) change is needed to analyze the impact of LULC change on ecological processes. The U.S. Geological Survey has produced spatially explicit, thematically detailed LULC projections for the conterminous United States. Four qualitative and quantitative scenarios of LULC change were developed, with characteristics consistent with the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emission Scenarios (SRES). The four quantified scenarios (A1B, A2, B1, and B2) served as input to the forecasting scenarios of land-use change (FORE-SCE) model. Four spatially explicit data sets consistent with scenario storylines were produced for the conterminous United...
Categories: Publication; Types: Journal Citation; Tags: Conterminous United States, Forest stand age, Land use and Land cover, Projections, Spatially-explicit modeling
Multi-decadal increases in dissolved organic carbon and alkalinity flux from the Mackenzie drainage basin to the Arctic Ocean
Riverine exports of organic and inorganic carbon (OC, IC) to oceans are intricately linked to processes occurring on land. Across high latitudes, thawing permafrost, alteration of hydrologic flow paths, and changes in vegetation may all affect this flux, with subsequent implications for regional and global carbon (C) budgets. Using a unique, multi-decadal dataset of continuous discharge coupled with water chemistry measurements for the Mackenzie River, we show major increases in dissolved OC (DOC) and IC (as alkalinity) fluxes since the early 1970s, for a watershed that covers 1.8 M km2 of northwestern Canada, and provides substantial inputs of freshwater and biogeochemical constituents to the Arctic Ocean. Over...
Categories: Publication; Types: Journal Citation; Tags: Alkalinity flux, Arctic Ocean, Carbon flux, Dissolved organic carbon, Mackenzie Drainage Basin,
Soil organic carbon (SOC) storage plays a major role in the global carbon cycle and is affected by many factors including land use/management changes (e.g., biofuel production-oriented changes). However, the contributions of various factors to SOC changes are not well understood and quantified. This study was designed to investigate the impacts of changing farming practices, initial SOC levels, and biological enhancement of grain production on SOC dynamics and to attribute the relative contributions of major driving forces (CO2 enrichment and farming practices) using a fractional factorial modeling design. The case study at a crop site in Iowa in the United States demonstrated that the traditional corn-soybean (CS)...
Categories: Publication; Types: Journal Citation; Tags: Carbon dynamics, Soil carbon, Soil organic carbon
Methods used to parameterize the spatially-explicit components of a state-and-transition simulation model
Spatially-explicit state-and-transition simulation models of land use and land cover (LULC) increase our ability to assess regional landscape characteristics and associated carbon dynamics across multiple scenarios. By characterizing appropriate spatial attributes such as forest age and land-use distribution, a state-and-transition model can more effectively simulate the pattern and spread of LULC changes. This manuscript describes the methods and input parameters of the Land Use and Carbon Scenario Simulator (LUCAS), a customized state-and-transition simulation model utilized to assess the relative impacts of LULC on carbon stocks for the conterminous U.S. The methods and input parameters are spatially explicit...
Categories: Publication; Types: Journal Citation; Tags: Land use and Land cover, Scenarios, Spatially-explicit modeling, State-and-transition simulation model
Projection of corn production and stover-harvesting impacts on soil organic carbon dynamics in the U.S. Temperate Prairies
Terrestrial carbon sequestration potential is widely considered as a realistic option for mitigating greenhouse gas emissions. However, this potential may be threatened by global changes including climate, land use, and management changes such as increased corn stover harvesting for rising production of cellulosic biofuel. Therefore, it is critical to investigate the dynamics of soil organic carbon (SOC) at regional or global scale. This study simulated the corn production and spatiotemporal changes of SOC in the U.S. Temperate Prairies, which covers over one-third of the U.S. corn acreage, using a biogeochemical model with multiple climate and land-use change projections. The corn production (either grain yield...
Categories: Publication; Types: Journal Citation; Tags: Carbon dynamics, Carbon flux, Carbon stock, Soil carbon, Soil organic carbon,
Evaluation of a model framework to estimate soil and soil organic carbon redistribution by water and tillage using 137Cs in two U.S. Midwest agricultural fields
Cultivated lands in the U.S. Midwest have been affected by soil erosion, causing soil organic carbon (SOC) redistribution in the landscape and other environmental and agricultural problems. The importance of SOC redistribution on soil productivity and crop yield, however, is still uncertain. In this study, we used a model framework, which includes the Unit Stream Power-based Erosion Deposition (USPED) and the Tillage Erosion Prediction (TEP) models, to understand the soil and SOC redistribution caused by water and tillage erosion in two agricultural fields in the U.S. Midwest. This model framework was evaluated for different digital elevation model (DEM) spatial resolutions (10-m, 24-m, 30-m, and 56-m) and topographic...
Categories: Publication; Types: Journal Citation; Tags: Cs-137, Deposition, Erosion, Midwest United States, Soil carbon,
Trends in snowpack chemistry and comparison to National Atmospheric Deposition Program results for the Rocky Mountains, US, 1993?2004
Seasonal snowpack chemistry data from the Rocky Mountain region of the US was examined to identify long-term trends in concentration and chemical deposition in snow and in snow-water equivalent. For the period 1993?2004, comparisons of trends were made between 54 Rocky Mountain Snowpack sites and 16 National Atmospheric Deposition Program wetfall sites located nearby in the region. The region was divided into three subregions: Northern, Central, and Southern. A non-parametric correlation method known as the Regional Kendall Test was used. This technique collectively computed the slope, direction, and probability of trend for several sites at once in each of the Northern, Central, and Southern Rockies subregions....
Categories: Publication; Types: Citation, Journal Citation; Tags: Atmospheric Environment, Rocky mountains, atmospheric deposition, chemical trends, nitrogen,
The Status, Habitat, and Response to Grazing of Water Vole Populations in the Big Horn Mountains of Wyoming, U.S.A.
Microtus richardsoni, the water vole, was listed as a sensitive species in Region 2 of the USDA Forest Service in 1994. Historical records indicate water voles were found in the Big Horn Mountains, but little was known about their current status. The purpose of this study was to locate water voles in the Big Horn Mountains of Wyoming, develop a habitat profile, and evaluate the extent to which livestock grazing affects them. Accessible creeks with habitat requirements for water voles were surveyed. Water voles were not captured below 2440 m. Grazed and ungrazed sites occupied by water voles were matched and analyzed for percent plant cover, dry weight biomass, riparian classification, mean stream depth, channel...
Categories: Publication; Types: Citation, Journal Citation; Tags: Arctic, Antarctic, and Alpine Research, WLCI Related Publication
Black-footed ferrets (Mustela nigripes) excavate subsoil from black-tailed prairie dog (Cynomys ludovicianus) burrows and deposit it in unique piles. Black-tailed prairie dogs tend to fill in or "plug" burrows visited or occupied by ferrets (Hillman 1968, Henderson et al. 1969, Fortenbery 1972). In this paper, we describe the configuration, rate of production, persistence, and seasonality of ferret diggings and rate of burrow plugging by prairie dogs within white-tailed prairie dog (C. leucurus) colonies. Published in Journal of Wildlife Management, volume 48, issue 4, on pages 1441 - 1444, in 1984.
Categories: Publication; Types: Citation, Journal Citation; Tags: JSTOR, Journal of Wildlife Management
Sedimentology, stratigraphy, and depositional environment of the crystal geyser dinosaur quarry, East-Central Utah
The Crystal Geyser Dinosaur Quarry, near Green River, Utah, is located at the base of the Lower Cretaceous (Barremian) Yellow Cat Member of the Cedar Mountain Formation. The quarry preserves a nearly monospecific accumulation of a new basal therizinosauroid, Falcarius utahensis. We used field descriptions and petrographic analysis to determine the depositional environment and development of the quarry strata. Results of these analyses suggest that the quarry represents multiple episodes of bone accumulation buried by spring and overbank flood deposits. Evidence for these previously undescribed spring deposits includes calcite macroscopic structures within the quarry strataâ€”such as pisolites and travertine fragmentsâ€”and...
Categories: Publication; Types: Citation, Journal Citation; Tags: PALAIOS
The pollen of three Ephedra taxa, Ephedra torreyana, E. trifurca and E. funerealeft right double arrowE. torreyana, showed a marked pollen dimorphism when examined using scanning electron microscopy. Typical pollen grains in all of these taxa have straight ridges, but the variant forms exhibit a highly folded ectexine. In addition, previously used characters such as the presence or absence of bifurcating valley structure do not appear to be uniform, even within a single microsporangium, suggesting that their value to taxonomic study should be reassessed. Published in Review of Palaeobotany and Palynology, volume 124, issue 3-4, on pages 325 - 334, in 2003.
Categories: Publication; Types: Citation, Journal Citation; Tags: Ephedra, Review of Palaeobotany and Palynology, pollen dimorphism, section Alatae
Increased Lesser Earless Lizard (Holbrookia maculata) Abundance on Gunnison's Prairie Dog Colonies and Short Term Responses to Artificial Prairie Dog Burrows
Our studies of the association between the lesser earless lizard (Holbrookia maculata) and Gunnison's prairie dogs (Cynomys gunnisoni) revealed: (1) the lesser earless lizard was more abundant on prairie dog colonies than off, (2) lesser earless lizard abundance was positively correlated with prairie dog burrow abundance; (3) lesser carless lizards responded positively to artificial burrows created on noncolonized areas; and (4) lesser earless lizards used prairie dog burrows as refuges from predators; however, the relative use of burrows was greatest at high and low temperature extremes. Although prairie dogs alter habitat in many ways, our study suggests that burrows are an important mechanism involved in the...
Categories: Publication; Types: Citation, Journal Citation; Tags: American Midland Naturalist, The University of Notre Dame
The synthesis of glycosaminoglycans (GAG) in a freshwater mussel was studied in organ culture using labeled precursors. The major GAGs synthesized were determined and characterized by chemical and enzymatic methods. They were shown to be heparin and an unusual type of heparan sulfate. Gills produced about 50% of each polymer; mantles synthesized little heparin and mostly the heparan-sulfate-like compound, which is similar to a GAG isolated previously from lobsters. No significant amounts of chondroitin sulfates were present. Histological data showed that the sulfate-labeled GAGs were present mainly in exterior pericellular and basement membrane locations of gills and mantle. That is, they would be in contact with...
Categories: Publication; Types: Citation, Journal Citation; Tags: The Biological Bulletin
The length of gestation is the number of days between fertilization and parturition, and the length of lactation is the number of days between parturition and weaning. Determination of these lengths is difficult for ground-dwelling squirrels such as prairie dogs, marmots, and ground squirrels that usually copulate, give birth, and nurse offspring underground. For Gunnison's prairie dogs (Cynomys gunnisoni), the mean +1 SD length of gestation is 29.3 ? 0.53 days (n = 124). The approximate length of lactation, estimated from the mean +1 SD duration between parturition and the first emergence of juveniles from the natal burrow, is 38.6 ? 2.08 days (n = 112). Published in Journal of Mammalogy, volume 78, issue 1, on...
Categories: Publication; Types: Citation, Journal Citation; Tags: Cynomys gunnisoni, Gunnison's prairie dog, Journal of Mammalogy, gestation, lactation,
Theoverthrust belt of western North America extends from British Columbiato southern Nevada. Large anticlines lie on thrust sheets alongthe length of this overthrust trend. Many oil and gasfields have been discovered on these structures in Canada, butsignificant hydrocarbon production in the United States has been primarilylimited to a productive salient in southwestern Wyoming and northeasternUtah (Figure 1). On 23 December 2003, Wolverine Gas andOil-Kings Meadow Ranches well 17-1 drilled into a 487-ft oilcolumn in the Navajo Sandstone in Sevier County, Utah. Thisnew significant oil reservoir is 146 miles southwest of thenearest thrust belt production at Pineview Field in Summit County,Utah. The discovery of what...
Categories: Publication; Types: Citation, Journal Citation; Tags: SEG, The Leading Edge
Sage-grouse (Centrocercus spp.) were abundant in all of Utah's 29 counties at the time of European settlement wherever sagebrush (Artemisia spp.) occurred. Greater Sage-Grouse (G. urophasianus) inhabited areas north and west of the Colorado River, and Gunnison Sage-Grouse (G. minimus) occupied suitable habitat south and east of the Colorado River. The largest Greater Sage-Grouse populations in Utah are currently restricted to suitable habitats in Box Elder, Garfield, Rich, Uintah, and Wayne Counties. A remnant breeding population of Gunnison Sage-Grouse occurs in eastern San Juan County. We stratified Greater Sage-Grouse populations (1971-2000) by counties where the 1996 to 2000 moving average for estimated spring...
Categories: Publication; Types: Citation, Journal Citation; Tags: Artemisia tridentata, Centrocercus minimus, Centrocercus urophasianus, DemoAtomFeed, Gunnison sage-grouse,
An accounting procedure is developed which determines a flow regime that is capable of transporting an amount of bedload sediment necessary to ensure channel stability downstream. The method allows for sediment buildup in the channel within geomorphic threshold limits during low flow periods. During periods of high runoff, enough water is bypassed to transport the stored sediment. The procedure utilizes only those flows of sufficient magnitude to maintain channel stability over the long run (25â€“50+ years). An example is presented which determines the volume of water and frequency of release for channel maintenance purposes downstream from a hypothetical water diversion project. Of some 1,200,000 acre feet generated...
As an estimate of species-level differences in the capacity to take up different forms of N, we measured plant uptake of 15N-NH4+, 15N-NO3- and 15N, -13C glycine within a set of herbaceous species collected from three alpine community types. Plants grown from cuttings in the greenhouse showed similar growth responses to the three forms of N but varied in the capacity to take up NH4+, NO3- and glycine. Glycine uptake ranged from approximately 42% to greater than 100% of NH4+ uptake; however, four out of nine species showed significantly greater uptake of either NH4+ or NO3- than of glycine. Relative concentrations of exchangeable N at the sites of plant collection did not correspond with patterns of N uptake among...
Categories: Publication; Types: Citation, Journal Citation; Tags: Plant and Soil, Springer Netherlands, ammonium, glycine, nitrate
Acidobacteria phylum sequences in uranium-contaminated subsurface sediments greatly expand the known diversity within the phylum
The abundance and composition of bacteria of the phylum Acidobacteria were surveyed in subsurface sediments from uranium-contaminated sites using amplification of 16S rRNA genes followed by clone/sequence analysis. Analysis of sequences from this study and public databases produced a revised and greatly expanded phylogeny of the Acidobacteria phylum consisting of 26 subgroups. Published in Applied and Environmental Microbiology, volume 73, issue 9, on pages 3113 - 6, in 2007.
Categories: Publication; Types: Citation, Journal Citation; Tags: Applied and Environmental Microbiology
A 40,000-year woodrat-midden record of vegetational and biogeographical dynamics in north-eastern Utah, USA
Aim: A conspicuous climatic and biogeographical transition occurs at 40?45� N in western North America. This pivot point marks a north?south opposition of wet and dry conditions at interannual and decadal time-scales, as well as the northern and southern limits of many dominant western plant species. Palaeoecologists have yet to focus on past climatic and biotic shifts along this transition, in part because it requires comparisons across dissimilar records [i.e. pollen from lacustrine sediments to the north and plant macrofossils from woodrat (Neotoma) middens to the south]. To overcome these limitations, we are extending the woodrat-midden record northward into the lowlands of the central Rocky Mountains. Published...
Categories: Publication; Types: Citation, Journal Citation; Tags: Holocene, Journal of Biogeography, extinction, glacial, invasions,