Expansion rate and geometry of floating vegetation mats on the margins of thermokarst lakes, northern Seward Peninsula, Alaska, USA
A.D. Parsekian, Benjamin M. Jones, M. Jones, G. Grosse, Anthony K.M. Walter, L. Slater
2011, Earth Surface Processes and Landforms (36) 1889-1897
Investigations on the northern Seward Peninsula in Alaska identified zones of recent (<50 years) permafrost collapse that led to the formation of floating vegetation mats along thermokarst lake margins. The occurrence of floating vegetation mat features indicates rapid degradation of near‐surface permafrost and lake expansion. This paper reports on the recent...
The GeoClaw software for depth-averaged flows with adaptive refinement
M.J. Berger, D.L. George, R.J. LeVeque, Kyle T. Mandli
2011, Advances in Water Resources (34) 1195-1206
Many geophysical flow or wave propagation problems can be modeled with two-dimensional depth-averaged equations, of which the shallow water equations are the simplest example. We describe the GeoClaw software that has been designed to solve problems of this nature, consisting of open source Fortran programs together with Python tools for...
Landscape features influence postrelease predation on endangered black-footed ferrets
S.A. Poessel, S.W. Breck, E. Biggins, T.M. Livieri, K.R. Crooks, L. Angeloni
2011, Journal of Mammalogy (92) 732-741
Predation can be a critical factor influencing recovery of endangered species. In most recovery efforts lethal and nonlethal influences of predators are not sufficiently understood to allow prediction of predation risk, despite its importance. We investigated whether landscape features could be used to model predation risk from coyotes (Canis latrans)...
Environmental conditions constrain the distribution and diversity of archaeal merA in Yellowstone National Park, Wyoming, U.S.A.
Y. Wang, E. Boyd, S. Crane, P. Lu-Irving, David P. Krabbenhoft, S. King, J. Dighton, G. Geesey, T. Barkay
2011, Microbial Ecology (62) 739-752
The distribution and phylogeny of extant protein-encoding genes recovered from geochemically diverse environments can provide insight into the physical and chemical parameters that led to the origin and which constrained the evolution of a functional process. Mercuric reductase (MerA) plays an integral role in mercury (Hg) biogeochemistry by catalyzing the...
Multivariate analyses with end-member mixing to characterize groundwater flow: Wind Cave and associated aquifers
Andrew J. Long, J.F. Valder
2011, Journal of Hydrology (409) 315-327
Principal component analysis (PCA) applied to hydrochemical data has been used with end-member mixing to characterize groundwater flow to a limited extent, but aspects of this approach are unresolved. Previous similar approaches typically have assumed that the extreme-value samples identified by PCA represent end members. The method presented herein is...
Adaptive resource management and the value of information
B. Kenneth Williams, M.J. Eaton, D.R. Breininger
2011, Ecological Modelling (222) 3429-3436
The value of information is a general and broadly applicable concept that has been used for several decades to aid in making decisions in the face of uncertainty. Yet there are relatively few examples of its use in ecology and natural resources management, and almost none that are framed in...
Multiplexed microsatellite recovery using massively parallel sequencing
T.N. Jennings, B.J. Knaus, T.D. Mullins, S. M. Haig, R.C. Cronn
2011, Molecular Ecology Resources (11) 1060-1067
Conservation and management of natural populations requires accurate and inexpensive genotyping methods. Traditional microsatellite, or simple sequence repeat (SSR), marker analysis remains a popular genotyping method because of the comparatively low cost of marker development, ease of analysis and high power of genotype discrimination. With the availability of massively parallel...
A computer program for flow-log analysis of single holes (FLASH)
F. D. Day-Lewis, C. D. Johnson, Frederick L. Paillet, K. J. Halford
2011, Ground Water (49) 926-931
A new computer program, FLASH (Flow-Log Analysis of Single Holes), is presented for the analysis of borehole vertical flow logs. The code is based on an analytical solution for steady-state multilayer radial flow to a borehole. The code includes options for (1) discrete fractures and (2) multilayer aquifers. Given vertical...
Repeatable source, site, and path effects on the standard deviation for empirical ground-motion prediction models
P.-S. Lin, B. Chiou, N. Abrahamson, M. Walling, C.-T. Lee, C.-T. Cheng
2011, Bulletin of the Seismological Society of America (101) 2281-2295
In this study, we quantify the reduction in the standard deviation for empirical ground-motion prediction models by removing ergodic assumption.We partition the modeling error (residual) into five components, three of which represent the repeatable source-location-specific, site-specific, and path-specific deviations from the population mean. A variance estimation procedure of these error...
On the use of log-transformation vs. nonlinear regression for analyzing biological power laws
X. Xiao, E.P. White, M.B. Hooten, S.L. Durham
2011, Ecology (92) 1887-1894
Power‐law relationships are among the most well‐studied functional relationships in biology. Recently the common practice of fitting power laws using linear regression (LR) on log‐transformed data has been criticized, calling into question the conclusions of hundreds of studies. It has been suggested that nonlinear regression (NLR) is preferable, but no...
Trophic connections in Lake Superior Part I: the offshore fish community
A.E. Gamble, T.R. Hrabik, J.D. Stockwell, D.L. Yule
2011, Journal of Great Lakes Research (37) 541-549
Detailed diet linkages within the offshore (> 80 m bathymetric depth) food web of Lake Superior are currently not well identified. We used analyses of fish stomach contents to create an empirically based food web model of the Lake Superior offshore fish community. Stomachs were collected seasonally (spring, summer, and...
Refuge habitats for fishes during seasonal drying in an intermittent stream: Movement, survival and abundance of three minnow species
S.W. Hodges, D.D. Magoulick
2011, Aquatic Sciences (73) 513-522
Drought and summer drying can be important disturbance events in many small streams leading to intermittent or isolated habitats. We examined what habitats act as refuges for fishes during summer drying, hypothesizing that pools would act as refuge habitats. We predicted that during drying fish would show directional movement into...
Management intensity alters decomposition via biological pathways
Kyle Wickings, A. Stuart Grandy, Sasha Reed, Cory Cleveland
2011, Biogeochemistry (104) 365-379
Current conceptual models predict that changes in plant litter chemistry during decomposition are primarily regulated by both initial litter chemistry and the stage-or extent-of mass loss. Far less is known about how variations in decomposer community structure (e.g., resulting from different ecosystem management types) could influence litter chemistry during decomposition....
Lower crustal relaxation beneath the Tibetan Plateau and Qaidam Basin following the 2001 Kokoxili earthquake
I. Ryder, R. Burgmann, F. Pollitz
2011, Geophysical Journal International (187) 613-630
In 2001 November a magnitude 7.8 earthquake ruptured a 400 km long portion of the Kunlun fault, northeastern Tibet. In this study, we analyse over five years of post-seismic geodetic data and interpret the observed surface deformation in terms of stress relaxation in the thick Tibetan lower crust. We model...
Mars Global Digital Dune Database (MGD3): North polar region (MC-1) distribution, applications, and volume estimates
R.K. Hayward
2011, Earth Surface Processes and Landforms (36) 1967-1972
The Mars Global Digital Dune Database (MGD3) now extends from 90°N to 65°S. The recently released north polar portion (MC‐1) of MGD3 adds ~844 000 km2 of moderate‐ to large‐size dark dunes to the previously released equatorial portion (MC‐2 to MC‐29) of the database. The database, available in GIS‐ and...
Dynamic habitat selection by two wading bird species with divergent foraging strategies in a seasonally fluctuating wetland
James M. Beerens, Dale E. Gawlik, Garth Herring, Mark I. Cook
2011, The Auk (128) 651-662
Seasonal and annual variation in food availability during the breeding season plays an influential role in the population dynamics of many avian species. In highly dynamic ecosystems like wetlands, finding and exploiting food resources requires a flexible behavioral response that may produce different population trends that vary with a species'...
A mass-balance model to separate and quantify colloidal and solute redistributions in soil
C.R. Bern, O.A. Chadwick, A.S. Hartshorn, L.M. Khomo, J. Chorover
2011, Chemical Geology (282) 113-119
Studies of weathering and pedogenesis have long used calculations based upon low solubility index elements to determine mass gains and losses in open systems. One of the questions currently unanswered in these settings is the degree to which mass is transferred in solution (solutes) versus suspension (colloids). Here we show...
Century-scale variability in global annual runoff examined using a water balance model
G.J. McCabe, D.M. Wolock
2011, International Journal of Climatology (31) 1739-1748
A monthly water balance model (WB model) is used with CRUTS2.1 monthly temperature and precipitation data to generate time series of monthly runoff for all land areas of the globe for the period 1905 through 2002. Even though annual precipitation accounts for most of the temporal and spatial variability in...
Short-term sandbar variability based on video imagery: Comparison between Time-Average and Time-Variance techniques
R.M.C. Guedes, L.J. Calliari, K. T. Holland, N.G. Plant, P.S. Pereira, F.N.A. Alves
2011, Marine Geology (289) 122-134
Time–exposure intensity (averaged) images are commonly used to locate the nearshore sandbar position (xb), based on the cross-shore locations of maximum pixel intensity (xi) of the bright bands in the images. It is not known, however, how the breaking patterns seen in Variance images (i.e. those created through standard deviation of pixel intensity...
Responses of ecosystem carbon cycling to climate change treatments along an elevation gradient
Zhuoting Wu, George W. Koch, Paul Dijkstra, Matthew A. Bowker, Bruce A. Hungate
2011, Ecosystems (14) 1066-1080
Global temperature increases and precipitation changes are both expected to alter ecosystem carbon (C) cycling. We tested responses of ecosystem C cycling to simulated climate change using field manipulations of temperature and precipitation across a range of grass-dominated ecosystems along an elevation gradient in northern Arizona. In 2002, we transplanted...
Large shift in source of fine sediment in the upper Mississippi River
P. Belmont, K.B. Gran, S.P. Schottler, P.R. Wilcock, S.S. Day, C. Jennings, J.W. Lauer, E. Viparelli, J.K. Willenbring, D.R. Engstrom, G. Parker
2011, Environmental Science & Technology (45) 8804-8810
Although sediment is a natural constituent of rivers, excess loading to rivers and streams is a leading cause of impairment and biodiversity loss. Remedial actions require identification of the sources and mechanisms of sediment supply. This task is complicated by the scale and complexity of large watersheds as well as...
Diffuse Pacific-North American plate boundary: 1000 km of dextral shear inferred from modeling geodetic data
T. Parsons, W. Thatcher
2011, Geology (39) 943-946
Geodetic measurements tell us that the eastern part of the Basin and Range Province expands in an east-west direction relative to stable North America, whereas the western part of the province moves to the northwest. We develop three-dimensional finite element representations of the western United States lithosphere in an effort...
The significance of turbulent flow representation in single-continuum models
Thomas Reimann, C. Rehrl, W.B. Shoemaker, T. Geyer, S. Birk
2011, Water Resources Research (47)
Karst aquifers exhibit highly conductive features caused from rock dissolution processes. Flow within these structures can become turbulent and therefore can be expressed by nonlinear gradient functions. One way to account for these effects is by coupling a continuum model with a conduit network. Alternatively, turbulent flow can be considered...
Transient electromagnetic study of basin fill sediments in the Upper San Pedro Basin, Mexico
M.W. Bultman, F. Gray
2011, Environmental Earth Sciences (64) 2091-2106
The Upper San Pedro River Basin in Mexico and the United States is an important riparian corridor that is coming under increasing pressure from growing populations and the associated increase in groundwater withdrawal. Several studies have produced three-dimensional maps of the basin fill sediments in the US portion of the...
Time-lapse three-dimensional inversion of complex conductivity data using an active time constrained (ATC) approach
M. Karaoulis, A. Revil, D.D. Werkema, B. J. Minsley, W.F. Woodruff, A. Kemna
2011, Geophysical Journal International (187) 237-251
Induced polarization (more precisely the magnitude and phase of impedance of the subsurface) is measured using a network of electrodes located at the ground surface or in boreholes. This method yields important information related to the distribution of permeability and contaminants in the shallow subsurface. We propose a new time-lapse...
