Climate controls on C3 vs. C4 productivity in North American grasslands from carbon isotope composition of soil organic matter
J.C. von Fischer, L.L. Tieszen, D. S. Schimel
2008, Global Change Biology (14) 1141-1155
We analyzed the ??13 C of soil organic matter (SOM) and fine roots from 55 native grassland sites widely distributed across the US and Canadian Great Plains to examine the relative production of C3 vs. C4 plants (hereafter %C4) at the continental scale. Our climate vs. %C4 results agreed well...
Monte Carlo method for determining earthquake recurrence parameters from short paleoseismic catalogs: Example calculations for California
T. Parsons
2008, Journal of Geophysical Research B: Solid Earth (113)
Paleoearthquake observations often lack enough events at a given site to directly define a probability density function (PDF) for earthquake recurrence. Sites with fewer than 10-15 intervals do not provide enough information to reliably determine the shape of the PDF using standard maximum-likelihood techniques (e.g., Ellsworth et al., 1999). In...
New global hydrography derived from spaceborne elevation data
B. Lehner, K.L. Verdin, A. Jarvis
2008, Eos, Transactions, American Geophysical Union (89) 93-94
To study the Earth system and to better understand the implications of global environmental change, there is a growing need for large-scale hydrographic data sets that serve as prerequisites in a variety of analyses and applications, ranging from regional watershed and freshwater conservation planning to global hydrological, climate, biogeochemical, and...
Mesozoic (Upper Jurassic-Lower Cretaceous) deep gas reservoir play, central and eastern Gulf coastal plain
E. A. Mancini, P. Li, D.A. Goddard, V.O. Ramirez, S.C. Talukdar
2008, American Association of Petroleum Geologists Bulletin (92) 283-308
The Mesozoic (Upper Jurassic-Lower Cretaceous) deeply buried gas reservoir play in the central and eastern Gulf coastal plain of the United States has high potential for significant gas resources. Sequence-stratigraphic study, petroleum system analysis, and resource assessment were used to characterize this developing play and to identify areas in the...
Storm-generated coral fragments - A viable source of transplants for reef rehabilitation
V. Garrison, G. Ward
2008, Biological Conservation (141) 3089-3100
Coral reefs throughout the world have been damaged by storms, diseases, coral predators, temperature anomalies, and human activities. During the past three decades, recovery has been limited and patchy. Although a damaged coral reef cannot be restored to its original condition, interest in reef restoration is increasing. In a pilot...
GSTARS computer models and their applications, part I: theoretical development
C.T. Yang, F.J.M. Simoes
2008, International Journal of Sediment Research (23) 197-211
GSTARS is a series of computer models developed by the U.S. Bureau of Reclamation for alluvial river and reservoir sedimentation studies while the authors were employed by that agency. The first version of GSTARS was released in 1986 using Fortran IV for mainframe computers. GSTARS 2.0 was released in 1998...
Biomarkers of mercury exposure at a mercury recycling facility in Ukraine
H.J. Gibb, K. Kozlov, J.P. Buckley, J. Centeno, V. Jurgenson, A. Kolker, K. Conko, E. Landa, B. Panov, Y. Panov, H. Xu
2008, Journal of Occupational and Environmental Hygiene (5) 483-489
This study evaluates biomarkers of occupational mercury exposure among workers at a mercury recycling operation in Gorlovka, Ukraine. The 29 study participants were divided into three occupational categories for analysis: (1) those who worked in the mercury recycling operation (Group A, n = 8), (2) those...
Terrace aggradation during the 1978 flood on Powder River, Montana, USA
J. A. Moody, R.H. Meade
2008, Geomorphology (99) 387-403
Flood processes no longer actively increase the planform area of terraces. Instead, lateral erosion decreases the area. However, infrequent extreme floods continue episodic aggradation of terraces surfaces. We quantify this type of evolution of terraces by an extreme flood in May 1978 on Powder River in southeastern Montana. Within an...
Impact effects and regional tectonic insights: Backstripping the Chesapeake Bay impact structure
T. Hayden, M. Kominz, David S. Powars, Lucy E. Edwards, K.G. Miller, J.V. Browning, A.A. Kulpecz
2008, Geology (36) 327-330
The Chesapeake Bay impact structure is a ca. 35.4 Ma crater located on the eastern seaboard of North America. Deposition returned to normal shortly after impact, resulting in a unique record of both impact-related and subsequent passive margin sedimentation. We use backstripping to show that the impact strongly affected sedimentation...
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...
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...
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...
Effects of scoria-cone eruptions upon nearby human communities
M.H. Ort, M.D. Elson, K.C. Anderson, W. A. Duffield, J.A. Hooten, D.E. Champion, G. Waring
2008, Geological Society of America Bulletin (120) 476-486
Scoria-cone eruptions are typically low in volume and explosivity compared with eruptions from stratovolcanoes, but they can affect local populations profoundly. Scoria-cone eruption effects vary dramatically due to eruption style, tephra blanket extent, climate, types of land use, the culture and complexity of the affected group, and resulting governmental action....
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...
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...
Secrets in the eyes of Black Oystercatchers: A new sexing technique
Brian M. Guzzetti, Sandra L. Talbot, David F. Tessler, Verena A. Gill, Edward C. Murphy
2008, Journal of Field Ornithology (79) 215-223
Sexing oystercatchers in the field is difficult because males and females have identical plumage and are similar in size. Although Black Oystercatchers (Haematopus bachmani) are sexually dimorphic, using morphology to determine sex requires either capturing both pair members for comparison or using discriminant analyses to assign sex probabilistically based on...
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...
A deep crustal fluid channel into the San Andreas Fault system near Parkfield, California
M. Becken, O. Ritter, S. K. Park, P. A. Bedrosian, U. Weckmann, M. Weber
2008, Geophysical Journal International (173) 718-732
Magnetotelluric (MT) data from 66 sites along a 45-km-long profile across the San Andreas Fault (SAF) were inverted to obtain the 2-D electrical resistivity structure of the crust near the San Andreas Fault Observatory at Depth (SAFOD). The most intriguing feature of the resistivity model is a steeply dipping upper...
