Soil nutrient-landscape relationships in a lowland tropical rainforest in Panama
F.K. Barthold, R.F. Stallard, H. Elsenbeer
2008, Forest Ecology and Management (255) 1135-1148
Soils play a crucial role in biogeochemical cycles as spatially distributed sources and sinks of nutrients. Any spatial patterns depend on soil forming processes, our understanding of which is still limited, especially in regards to tropical rainforests. The objective of our study was to investigate the effects of landscape properties,...
Middle UV to near-IR spectrum of electron-excited SO2
J.M. Ajello, A. Aguilar, R.S. Mangina, G.K. James, P. Geissler, L. Trafton
2008, Journal of Geophysical Research E: Planets (113)
We investigated the electron impact–induced fluorescence spectrum of SO2 to provide excitation cross sections for modeling Io's emission spectrum and analyzing Cassini Imaging Science Subsystem observations. The electron-excited middle-ultraviolet visible optical near-infrared (VOIR) emission spectrum of SO2 gas was generated in the laboratory and studied from 2000 to 11,000 Å at a...
Use of an annular chamber for testing thermal preference of westslope cutthroat trout and rainbow trout
T.E. McMahon, E.A. Bear, A.V. Zale
2008, Journal of Freshwater Ecology (23) 55-63
Remaining populations of westslope cutthroat trout (Oncorhynchus clarkii lewisi) in western North America are primarily confined to cold headwaters whereas nonnative rainbow trout (Oncorhynchus mykiss) predominate in warmer, lower elevation stream sections historically occupied by westslope cutthroat trout. We tested whether differing thermal preferences could account for the spatial segregation...
Efficient implementation of the Metropolis-Hastings algorithm, with application to the Cormack-Jolly-Seber model
W.A. Link, R. J. Barker
2008, Conference Paper, Environmental and Ecological Statistics
Judicious choice of candidate generating distributions improves efficiency of the Metropolis-Hastings algorithm. In Bayesian applications, it is sometimes possible to identify an approximation to the target posterior distribution; this approximate posterior distribution is a good choice for candidate generation. These observations are applied to analysis of the Cormack-Jolly-Seber model and...
Multidecadal climate-induced variability in microseisms
R.C. Aster, D.E. McNamara, P.D. Bromirski
2008, Seismological Research Letters (79) 194-202
Microseisms are the most ubiquitous continuous seismic signals on Earth at periods between approximately 5 and 25 s (Peterson 1993; Kedar and Webb 2005). They arise from atmospheric energy converted to (primarily) Rayleigh waves via the intermediary of wind-driven oceanic swell and occupy a period band that is uninfluenced by...
Use of volatile organic components in scat to identify canid species
E. Burnham, Louis C. Bender, G.A. Eiceman, K.M. Pierce, S. Prasad
2008, Journal of Wildlife Management (72) 792-797
Identification of wildlife species from indirect evidence can be an important part of wildlife management, and conventional +methods can be expensive or have high error rates. We used chemical characterization of the volatile organic constituents (VOCs) in scat as a method to identify 5 species of North American canids from...
More than 400 million years of evolution and some plants still can't make it on their own: Plant stress tolerance via fungal symbiosis
R. Rodriguez, R. Redman
2008, Conference Paper, Journal of Experimental Botany
All plants in natural ecosystems are thought to be symbiotic with mycorrhizal and/or endophytic fungi. Collectively, these fungi express different symbiotic lifestyles ranging from parasitism to mutualism. Analysis of Colletotrichum species indicates that individual isolates can express either parasitic or mutualistic lifestyles depending on the host genotype colonized. The endophyte...
Effect of 3-D viscoelastic structure on post-seismic relaxation from the 2004 M = 9.2 Sumatra earthquake
F. Pollitz, P. Banerjee, K. Grijalva, B. Nagarajan, R. Burgmann
2008, Geophysical Journal International (173) 189-204
The 2004 M=9.2 Sumatra-Andaman earthquake profoundly altered the state of stress in a large volume surrounding the ???1400 km long rupture. Induced mantle flow fields and coupled surface deformation are sensitive to the 3-D rheology structure. To predict the post-seismic motions from this earthquake, relaxation of a 3-D spherical viscoelastic...
Late-stage sulfides and sulfarsenides in Lower Cambrian black shale (stone coal) from the Huangjiawan mine, Guizhou Province, People's Republic of China
H. E. Belkin, K. Luo
2008, Mineralogy and Petrology (92) 321-340
The Ni-Mo Huangjiawan mine, Guizhou Province, People's Republic of China, occurs in Lower Cambrian black shale (stone coal) in an area where other mines have recently extracted ore from the same horizon. Detailed electron microprobe (EMPA) and scanning electron microscope (SEM) analyses of representative thin sections have revealed a complex...
Creation of a continent recorded in zircon zoning
D.E. Moser, J. R. Bowman, J. Wooden, J.W. Valley, F. Mazdab, N. Kita
2008, Geology (36) 239-242
We have discovered a robust microcrystalline record of the early genesis of North American lithosphere preserved in the U-Pb age and oxygen isotope zoning of zircons from a lower crustal paragneiss in the Neoarchean Superior province. Detrital igneous zircon cores with ??18O values of 5.1???-7.1??? record creation of primitive to...
Broadband seismic measurements of degassing activity associated with lava effusion at Popocatépetl Volcano, Mexico
Alejandra Arciniega-Ceballos, Bernard A. Chouet, Phillip Dawson, Guenter Asch
2008, Journal of Volcanology and Geothermal Research (170) 12-23
From November 1999 through July 2000, a broadband seismic experiment was carried out at Popocatépetl Volcano to record seismic activity over a wide period range (0.04–100 s). We present an overview of the seismicity recorded during this experiment and discuss results of analyses of long-period (LP) and very-long-period (VLP) seismic signals...
Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems
G.P. Waite, B. A. Chouet, P.B. Dawson
2008, Journal of Geophysical Research B: Solid Earth (113)
The current eruption at Mount St. Helens is characterized by dome building and shallow, repetitive, long-period (LP) earthquakes. Waveform cross-correlation reveals remarkable similarity for a majority of the earthquakes over periods of several weeks. Stacked spectra of these events display multiple peaks between 0.5 and 2 Hz that are common...
Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations
N. K. Ganju, N. Knowles, D. H. Schoellhamer
2008, Journal of Hydrology (349) 512-523
In this study we used hydrologic proxies to develop a daily sediment load time-series, which agrees with decadal sediment load estimates, when integrated. Hindcast simulations of bathymetric change in estuaries require daily sediment loads from major tributary rivers, to capture the episodic delivery of sediment during multi-day freshwater flow pulses....
Gender identification of Caspian Terns using external morphology and discriminant function analysis
Joshua T. Ackerman, John Y. Takekawa, J.D. Bluso, J.L. Yee, Collin A. Eagles-Smith
2008, Wilson Journal of Ornithology (120) 378-383
Caspian Tern (Sterna caspia) plumage characteristics are sexually monochromatic and gender cannot easily be distinguished in the field without extensive behavioral observations. We assessed sexual size dimorphism and developed a discriminant function to assign gender in Caspian Terns based on external morphology. We collected and measured Caspian Terns in San...
Evidence for fish dispersal from spatial analysis of stream network topology
N.P. Hitt, P. L. Angermeier
2008, Journal of the North American Benthological Society (27) 304-320
Developing spatially explicit conservation strategies for stream fishes requires an understanding of the spatial structure of dispersal within stream networks. We explored spatial patterns of stream fish dispersal by evaluating how the size and proximity of connected streams (i.e., stream network topology) explained variation in fish assemblage structure and how...
Are fractal dimensions of the spatial distribution of mineral deposits meaningful?
G. L. Raines
2008, Natural Resources Research (17) 87-97
It has been proposed that the spatial distribution of mineral deposits is bifractal. An implication of this property is that the number of deposits in a permissive area is a function of the shape of the area. This is because the fractal density functions of deposits are dependent on the...
Representing general theoretical concepts in structural equation models: The role of composite variables
J.B. Grace, K.A. Bollen
2008, Environmental and Ecological Statistics (15) 191-213
Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we...
Comparative study of transport processes of nitrogen, phosphorus, and herbicides to streams in five agricultural basins, USA
Joseph L. Domagalski, S. Ator, R. Coupe, K. McCarthy, D. Lampe, Mark W. Sandstrom, N. Baker
2008, Journal of Environmental Quality (37) 1158-1169
Agricultural chemical transport to surface water and the linkage to other hydrological compartments, principally ground water, was investigated at five watersheds in semiarid to humid climatic settings. Chemical transport was affected by storm water runoff, soil drainage, irrigation, and how streams were linked to shallow ground water systems. Irrigation practices...
Efficacy of algal metrics for assessing nutrient and organic enrichment in flowing waters
S. D. Porter, D. K. Mueller, N.E. Spahr, M.D. Munn, N. M. Dubrovsky
2008, Freshwater Biology (53) 1036-1054
1. Algal-community metrics were calculated for periphyton samples collected from 976 streams and rivers by the U.S. Geological Survey’s National Water-Quality Assessment (NAWQA) Programme during 1993–2001 to evaluate national and regional relations with water chemistry and to compare whether algal-metric values differ significantly among undeveloped and developed land-use classifications. 2. Algal...
Comparison of Mexican wolf and coyote diets in Arizona and New Mexico
R. Carrera, W. Ballard, P. Gipson, B.T. Kelly, P.R. Krausman, M.C. Wallace, C. Villalobos, D.B. Wester
2008, Journal of Wildlife Management (72) 376-381
Interactions between wolves (Canis lupus) and coyotes (C. latrans) can have significant impacts on their distribution and abundance. We compared diets of recently translocated Mexican wolves (C. l. baileyi) with diets of resident coyotes in Arizona and New Mexico, USA. We systematically collected scats during 2000 and 2001. Coyote diet...
The influence of cryogenic processes on the erosional Arctic shoreface
F. Are, E. Reimnitz, M. Grigoriev, H.-W. Hubberten, V. Rachold
2008, Journal of Coastal Research (24) 110-121
Coastal dynamics and shoreface relief in ice-free seas are a function of hydrodynamic interactions between the sea and bottom sediments. In the Arctic, additional, cryogenic factors such as permafrost and the action of sea ice influence coastal processes. The goal of our paper is to assess this influence, mainly on...
Cost-effective management alternatives for Snake river chinook salmon: A biological-economic synthesis
D.L. Halsing, M.R. Moore
2008, Conservation Biology (22) 338-350
The mandate to increase endangered salmon populations in the Columbia River Basin of North America has created a complex, controversial resource-management issue. We constructed an integrated assessment model as a tool for analyzing biological-economic trade-offs in recovery of Snake River spring- and summer-run chinook salmon (Oncorhynchus tshawytscha). We merged 3...
Post-wildfire erosion response in two geologic terrains in the western USA
J. A. Moody, D.A. Martin, S.H. Cannon
2008, Geomorphology (95) 103-118
Volumes of eroded sediment after wildfires vary substantially throughout different geologic terrains across the western United States. These volumes are difficult to compare because they represent the response to rainstorms and runoff with different characteristics. However, by measuring the erosion response as the erodibility efficiency of water to detach and...
Innovations in individual feature history management - The significance of feature-based temporal model
J. Choi, J.C. Seong, B. Kim, E.L. Usery
2008, GeoInformatica (12) 1-20
A feature relies on three dimensions (space, theme, and time) for its representation. Even though spatiotemporal models have been proposed, they have principally focused on the spatial changes of a feature. In this paper, a feature-based temporal model is proposed to represent the changes of both space and theme independently....
Rethinking avian response to Tamarix on the lower Colorado River: A threshold hypothesis
Charles van Riper III, K.L. Paxton, C. O'brien, P.B. Shafroth, L.J. McGrath
2008, Restoration Ecology (16) 155-167
Many of the world's large river systems have been greatly altered in the past century due to river regulation, agriculture, and invasion of introduced Tamarix spp. (saltcedar, tamarisk). These riverine ecosystems are known to provide important habitat for avian communities, but information on responses of birds to differing levels of...
