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This article presents an application of a risk assessment approach in characterising the risks associated with safety violations in underground bituminous mines in Pennsylvania using the Mine Safety and Health Administration (MSHA) citation database. The MSHA database on citations provides an opportunity to assess risks in mines through scrutiny of violations of mandatory safety standards. In this study, quantitative risk assessment is performed, which allows determination of the frequency of occurrence of safety violations (through associated citations) as well as the consequences of them in terms of penalty assessments. Focus is on establishing risk matrices on citation experiences of mines, which can give early...
We simulate three types of forced-gradient tracer tests (converging radial flow, unequal strength two well, and equal strength two well) and natural-gradient tracer tests in multiple realizations of heterogeneous two-dimensional aquifers with a hydraulic conductivity distribution characterized by a spherical variogram. We determine longitudinal dispersivities (αL) by analysis of forced-gradient test breakthrough curves at the pumped well and by spatial moment analysis of tracer concentrations during the natural-gradient tests. Results show that among the forced-gradient tests, a converging radial-flow test tends to yield the smallest αL, an equal strength two-well test tends to yield the largest αL, and an unequal...
In this study, we have integrated a suite of Holocene paleoclimatic proxies with mathematical modeling in an attempt to obtain a comprehensive picture of how watersheds respond to past climate change. A three-dimensional surface-water–groundwater model was developed to assess the effects of mid-Holocene climate change on water resources within the Crow Wing Watershed, Upper Mississippi Basin in north central Minnesota. The model was first calibrated to a 50 yr historical record of average annual surface-water discharge, monthly ground-water levels, and lake-level fluctuations. The model was able to reproduce reasonably well long-term historical records (1949–1999) of water-table and lake-level fluctuations across...
Ecological processes of low-productivity ecosystems have long been considered to be driven by abiotic controls with biotic interactions playing an insignificant role. However, existing studies present conflicting evidence concerning the roles of these factors, in part due to the short temporal extent of most data sets and inability to test indirect effects of environmental variables modulated by biotic interactions. Using structural equation modeling to analyze 65 years of perennial vegetation change in the Sonoran Desert, we found that precipitation had a stronger positive effect on recruitment beneath existing canopies than in open microsites due to reduced evaporation rates. Variation in perennial canopy cover...
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This dataset represents presence of Red Pine (Pinus resinosa) at year 0 (1995) in Minnesota (USA) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Restoration harvest rates and intensities were simulated.
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This dataset represents presence of Black Spruce (Picea mariana) at year 150 (2145) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Restoration harvest rates and intensities were simulated.
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This dataset represents presence of Sugar Maple (Acer saccharum) at year 100 (2095) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Restoration harvest rates and intensities were simulated.
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This dataset represents presence of Red Pine (Pinus resinosa) at year 50 (2045) in Minnesota (USA) from a single model run of LANDIS-II. The simulation assumed Intergovernmental Panel on Climate Change (IPCC) B2 emissions (moderate) and used the Hadley 3 global circulation model. Contemporary harvest rates and intensities were simulated.
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This dataset shows modelled habitat suitability for the Pacific-slope Flycatcher (Empidonax difficilis) under current and projected future conditions. We built habitat suitability models for 237 bird, 117 mammal, and 12 amphibian species. Species were chosen for inclusion in the study based on a simple set of criteria. For a species to be included in the study, it had to be primarily associated with terrestrial habitats, have a digital map of its current range, and have some portion of its current distribution intersect with the study area extent. In addition, we restricted the list of species used in the study to those for which a well-performing continental-scale model could be built. Digital species range maps...
Abstract (from http://journals.ametsoc.org/doi/abs/10.1175/JHM-D-14-0236.1): Global climate model (GCM) output typically needs to be bias corrected before it can be used for climate change impact studies. Three existing bias correction methods, and a new one developed here, are applied to daily maximum temperature and precipitation from 21 GCMs to investigate how different methods alter the climate change signal of the GCM. The quantile mapping (QM) and cumulative distribution function transform (CDF-t) bias correction methods can significantly alter the GCM’s mean climate change signal, with differences of up to 2°C and 30% points for monthly mean temperature and precipitation, respectively. Equidistant quantile...
Abstract (from http://link.springer.com/article/10.1007%2Fs10980-015-0294-1): Context Tree species distribution and abundance are affected by forces operating at multiple scales. Niche and biophysical process models have been commonly used to predict climate change effects at regional scales, however, these models have limited capability to include site-scale population dynamics and landscape-scale disturbance and dispersal. We applied a landscape modeling approach that incorporated three levels of spatial hierarchy (pixel, landtype, and ecological subsection) to model regional-scale shifts in forest composition under climate change. Objective To determine (1) how importance value of individual species will...
An accurate and management sensitive simulation model for tile-drained Midwestern soils is needed to optimize the use of agricultural management practices (e.g., winter cover crops) to reduce nitrate leaching without adversely affecting corn yield. Our objectives were to enhance the Agricultural Production Systems Simulator (APSIM) for tile drainage, test the modified model for several management scenarios, and then predict nitrate leaching with and without winter wheat cover crop. Twelve years of data (1990–2001) from northeast Iowa were used for model testing. Management scenarios included continuous corn and corn–soybean rotations with single or split N applications. For 38 of 44 observations, yearly drain flow...
This study set out to answer the question: “What data and modeling frameworks are needed to provide scientists reliable, climate-informed, water temperature estimates for freshwater ecosystems that can assist watershed management decision making?” To accomplish this, researchers gathered existing stream temperature data, identified data gaps, deployed stream temperature monitoring devices, and developed and tested a stream temperature model that could be regionalized across the Northeast Climate Science Center (NE CSC) domain. Polebitski and colleagues partnered with another NE CSC funded project team, NorEaST-Stream Temperature Web Portal Demonstration and Application, led by Jana Stewart (USGS Wisconsin Water...
Boreal soils in permafrost regions contain vast quantities of frozen organic material that is released to terrestrial and aquatic environments via subsurface flow paths as permafrost thaws. Longer flow paths may allow chemical reduction of solutes, nutrients, and contaminants, with implications for greenhouse gas emissions and aqueous export. Predicting boreal catchment runoff is complicated by soil heterogeneities related to variability in active layer thickness, soil type, fire history, and preferential flow potential. By coupling measurements of permeability, infiltration potential, and water chemistry with a stream chemistry end-member mixing model, we tested the hypothesis that organic soils and burned slopes...
To accurately represent subsurface flow in a hydrologic model of permafrost terrain during spring thaw, an understanding of soil thaw and soil thaw rates is required. Research was conducted on an organic-covered hillslope in Granger Basin, Yukon Territory, to quantify relationships between net radiation, snowmelt and soil thaw energy. The infiltration and freezing of meltwater into the soil may contribute to pre-thaw warming. When this energy (1.82 MJ·m -2 ·d-1 ) is taken into account, the daily mean contribution to soil thaw from net radiation is approximately 9%. Measured and estimated soil thaw depths compared well (R2 = 0.75) when energy was distributed across the hillslope. This research contributes to the...
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Old Crow Flats is a 5600 km2 glaciolacustrine plain that straddles the forest-tundra ecotone in northern Yukon. Continuous taiga corridors occur in the entrenched river valleys, where annual mean ground temperatures (Tg) at the depth of zero annual amplitude at two locations were ?3.1 and ?4.0ºC in 2013. On the Flats, the vegetation cover is patchy, and Tg varied between ?5.1 and ?2.6ºC. Annual mean near-surface permafrost temperatures (Tps) measured on the Flats between 2008 and 2011 in patches of taiga, tall shrubs and low shrubs were correlated with local snow depth. Snow depth was controlled by vegetation height if the snow supply was not limited, for example, where low shrubs and large lakes dominate the landscape....
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Ecosystem-scale methane (CH 4 ) exchange was observed in a poorly-drained black spruce forest over permafrost in interior Alaska during the snow-free seasons of 2011–2013, using the eddy covariance technique. The magnitude of average CH 4 exchange differed depending on wind direction, reflecting spatial variation in soil moisture condition around the observation tower, due to elevation change within the small catchment. In the drier upper position, the seasonal variation in CH 4 emission was explained by the variation in soil water content only. In the wetter bottom, however, in addition to soil temperature and soil water content, seasonal thaw depth of frozen soil was also an important variable explaining the seasonal...
Intensification of permafrost thaw has increased the frequency and magnitude of large permafrost slope disturbances (mega slumps) in glaciogenic terrain of northwestern Canada. Individual thermokarst disturbances up to 40 ha in area have made large volumes of previously frozen, highly weatherable fine-grained sediments available for leaching and transport to adjacent streams, significantly increasing sediment and solute loads in these systems. To test the effects of this climate-sensitive disturbance regime on the ecology of Arctic streams, we explored the relationship between physical and chemical variables and benthic macroinvertebrate communities in disturbed and undisturbed stream reaches in the Peel Plateau...


map background search result map search result map Pacific-slope Flycatcher (Empidonax difficilis) Habitat Suitability Change Models Minnesota (USA) Climate Change Project: Red Pine at Year 0 (1995), assuming emissions scenario B2, Hadley3 GCM, restoration harvest rates and intensity Minnesota (USA) Climate Change Project: Red Pine at Year 50 (2045), assuming emissions scenario B2, Hadley3 GCM, contemporary harvest rates and intensity Minnesota (USA) Climate Change Project: Black Spruce at Year 150 (2145), assuming emissions scenario B2, Hadley3 GCM, restoration harvest rates and intensity Minnesota (USA) Climate Change Project: Sugar Maple at Year 100 (2095), assuming emissions scenario B2, Hadley 3 GCM, restoration harvest rates and intensity Vegetation-Permafrost Relations within the Forest-Tundra Ecotone near Old Crow, Northern Yukon, Canada Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen Methane exchange in a poorly-drained black spruce forest over permafrost observed using the eddy covariance technique Seasonal ice and hydrologic controls on dissolved organic carbon and nitrogen concentrations in a boreal-rich fen Minnesota (USA) Climate Change Project: Red Pine at Year 0 (1995), assuming emissions scenario B2, Hadley3 GCM, restoration harvest rates and intensity Minnesota (USA) Climate Change Project: Red Pine at Year 50 (2045), assuming emissions scenario B2, Hadley3 GCM, contemporary harvest rates and intensity Minnesota (USA) Climate Change Project: Black Spruce at Year 150 (2145), assuming emissions scenario B2, Hadley3 GCM, restoration harvest rates and intensity Minnesota (USA) Climate Change Project: Sugar Maple at Year 100 (2095), assuming emissions scenario B2, Hadley 3 GCM, restoration harvest rates and intensity Methane exchange in a poorly-drained black spruce forest over permafrost observed using the eddy covariance technique Vegetation-Permafrost Relations within the Forest-Tundra Ecotone near Old Crow, Northern Yukon, Canada Pacific-slope Flycatcher (Empidonax difficilis) Habitat Suitability Change Models