Nonstructural leaf carbohydrates dynamics of Pinus edulis during drought-induced tree mortality reveal role for carbon metabolism in mortality mechanism
Henry D. Adams, Matthew J. Germino, David D. Breshears, Greg A. Barron-Gafford, Maite Guardiola-Claramonte, Chris B. Zou, Travis E. Huxman
2013, New Phytologist (197) 1142-1151
* Vegetation change is expected with global climate change, potentially altering ecosystem function and climate feedbacks. However, causes of plant mortality, which are central to vegetation change, are understudied, and physiological mechanisms remain unclear, particularly the roles of carbon metabolism and xylem function. * We report analysis of foliar nonstructural carbohydrates...
Application of the SPARROW model to assess surface-water nutrient conditions and sources in the United States Pacific Northwest
Daniel R. Wise, Henry M. Johnson
2013, Scientific Investigations Report 2013-5103
The watershed model SPARROW (Spatially Referenced Regressions on Watershed attributes) was used to estimate mean annual surface-water nutrient conditions (total nitrogen and total phosphorus) and to identify important nutrient sources in catchments of the Pacific Northwest region of the United States for 2002. Model-estimated nutrient yields were generally higher in...
Uranium redox transition pathways in acetate-amended sediments
John R. Bargar, Kenneth H. Williams, Kate M. Campbell, Philip E. Long, Joanne E. Stubbs, Elenal I. Suvorova, Juan S. Lezama-Pacheco, Daniel S. Alessi, Malgorzata Stylo, Samuel M. Webb, James A. Davis, Daniel E. Giammar, Lisa Y. Blue, Rizlan Bernier-Latmani
2013, PNAS (110) 4506-4511
Redox transitions of uranium [from U(VI) to U(IV)] in low-temperature sediments govern the mobility of uranium in the environment and the accumulation of uranium in ore bodies, and inform our understanding of Earth’s geochemical history. The molecular-scale mechanistic pathways of these transitions determine the U(IV) products formed, thus influencing uranium...
Geologic controls on regional and local erosion rates of three northern Gulf of Mexico barrier-island systems
David C. Twitchell, James G. Flocks, Elizabeth A. Pendleton, Wayne E. Baldwin
2013, Journal of Coastal Research 32-45
The stratigraphy of sections of three barrier island systems in the northeastern Gulf of Mexico (Apalachicola, Mississippi, and Chandeleur) have been mapped using geophysical and coring techniques to assess the influence of geologic variations in barrier lithosomes and adjoining inner shelf deposits on long-term rates of shoreline change at regional...
New thermochronometric constraints on the Tertiary landscape evolution of the central and eastern Grand Canyon, Arizona
John P. Lee, Daniel F. Stockli, S.A. Kelley, J. Pederson, K. E. Karlstrom, T.A. Ehlers
2013, Geosphere (9) 216-228
Thermal histories are modeled from new apatite (U-Th)/He and apatite fission-track data in order to quantitatively constrain the landscape evolution of the Grand Canyon region. Fifty new samples and their associated thermochronometric ages are presented here. Samples span from Lee’s Ferry in the east to Quartermaster Canyon in the west...
Forest cutting and impacts on carbon in the eastern United States
Decheng Zhou, Shuguang Liu, Jennifer Oeding, Shuqing Zhao
2013, Scientific Reports (3)
Forest cutting is a major anthropogenic disturbance that affects forest carbon (C) storage and fluxes. Yet its characteristics and impacts on C cycling are poorly understood over large areas. Using recent annualized forest inventory data, we estimated cutting-related loss of live biomass in the eastern United States was 168 Tg C...
Holocene fire occurrence and alluvial responses at the leading edge of pinyon–juniper migration in the Northern Great Basin, USA
Kerrie N. Weppner, Jennifer L. Pierce, Julio L. Betancourt
2013, Quaternary Research (80) 143-157
Fire and vegetation records at the City of Rocks National Reserve (CIRO), south-central Idaho, display the interaction of changing climate, fire and vegetation along the migrating front of single-leaf pinyon (Pinus monophylla) and Utah juniper (Juniperus osteosperma). Radiocarbon dating of alluvial charcoal reconstructed local fire occurrence and geomorphic...
Nutrient enrichment and fish nutrient tolerance: Assessing biologically relevant nutrient criteria
Michael R. Meador
2013, Journal of the American Water Resources Association (49) 253-263
Relationships between nutrient concentrations and fish nutrient tolerance were assessed relative to established nutrient criteria. Fish community, nitrate plus nitrite (nitrate), and total phosphorus (TP) data were collected during summer low-flow periods in 2003 and 2004 at stream sites along a nutrient-enrichment gradient in an agricultural basin in Indiana and...
The airspace is habitat
Robert H. Diehl
2013, Trends in Ecology and Evolution (28) 377-379
A preconception concerning habitat persists and has gone unrecognized since use of the term first entered the lexicon of ecological and evolutionary biology many decades ago. Specifically, land and water are considered habitats, while the airspace is not. This might at first seem a reasonable, if unintended, demarcation, since years...
Land-use change, economics, and rural well-being in the Prairie Pothole Region of the United States
William R. Gascoigne, Dana L.K. Hoag, Rex R. Johnson, Lynne M. Koontz, Catherine Cullinane Thomas
2013, Fact Sheet 2013-3046
This fact sheet highlights findings included in a comprehensive new report (see USGS Professional Paper 1800) which investigated land-use change, economic characteristics, and rural community well-being in the Prairie Pothole Region of the United States. Once one of the largest grassland-wetlands ecosystems on earth, the North American prairie has experienced...
Revision of Fontes & Garnier's model for the initial 14C content of dissolved inorganic carbon used in groundwater dating
Liang-Feng Han, Niel Plummer
2013, Chemical Geology (351) 105-114
The widely applied model for groundwater dating using 14C proposed by Fontes and Garnier (F&G) (Fontes and Garnier, 1979) estimates the initial 14C content in waters from carbonate-rock aquifers affected by isotopic exchange. Usually, the model of F&G is applied in one of two ways: (1) using a single 13C...
Deforestation trends of tropical dry forests in central Brazil
Carlos A. Bianchi, Susan M. Haig
2013, Biotropica (45) 395-400
Tropical dry forests are the most threatened forest type in the world yet a paucity of research about them stymies development of appropriate conservation actions. The Paranã River Basin has the most significant dry forest formations in the Cerrado biome of central Brazil and is threatened by intense land conversion...
Exploring Hawaiian volcanism
Michael P. Poland, Paul G. Okubo, Ken Hon
2013, Eos, Transactions, American Geophysical Union (94) 72-72
In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided...
Management, morphological, and environmental factors influencing Douglas-fir bark furrows in the Oregon Coast Range
Christopher D. Sheridan, Klaus J. Puettmann, Manuela M.P. Huso, Joan C. Hagar, Kristen R. Falk
2013, Western Journal of Applied Forestry (28) 97-106
Many land managers in the Pacific Northwest have the goal of increasing late-successional forest structures. Despite the documented importance of Douglas-fir tree bark structure in forested ecosystems, little is known about factors influencing bark development and how foresters can manage development. This study investigated the relative importance of tree size,...
U.S. Geological Survey water-resource monitoring activities in support of the Wyoming Landscape Conservation Initiative
Suzanna Soileau, Kirk Miller
2013, WLCI Fact Sheet 4
The quality of the Nation’s water resources are vital to the health and well-being of both our communities and the natural landscapes we value. The U.S. Geological Survey investigates the occurrence, quantity, quality, distribution, and movement of surface water and groundwater and provides this information to engineers, scientists, managers, educators,...
Impact of Late Holocene climate variability and anthropogenic activities on Biscayne Bay (Florida, U.S.A.): Evidence from diatoms
Anna Wachnicka, Evelyn Gaiser, G. Lynn Wingard, Henry Briceno, Peter Harlem
2013, Palaeogeography, Palaeoclimatology, Palaeoecology (371) 80-92
Shallow marine ecosystems are experiencing significant environmental alterations as a result of changing climate and increasing human activities along coasts. Intensive urbanization of the southeast Florida coast and intensification of climate change over the last few centuries changed the character of coastal ecosystems in the semi-enclosed Biscayne Bay, Florida. In...
Hysteresis in suspended sediment to turbidity relations due to changing particle size distributions
Mark N. Landers, Terry W. Sturm
2013, Water Resources Research (49) 5487-5500
Turbidity (T) is the most ubiquitous of surrogate technologies used to estimate suspended-sediment concentration (SSC). The effects of sediment size on turbidity are well documented; however, effects from changes in particle size distributions (PSD) are rarely evaluated. Hysteresis in relations of SSC-to-turbidity (SSC~T) for single stormflow events was observed and...
Development of a geodatabase for springs within and surrounding outcrops of the Trinity aquifer in northern Bexar County, Texas, 2010-11
Allan K. Clark, Diane E. Pedraza
2013, Fact Sheet 2013-3044
The Trinity aquifer is an important source of groundwater in central Texas, including Bexar County, where population growth has resulted in an increased demand for water (Ashworth, 1983; Mace and others, 2000). Numerous springs issue from rock outcrops within and surrounding the Trinity aquifer in northern Bexar County (fig. 1)....
Software for analysis of chemical mixtures--composition, occurrence, distribution, and possible toxicity
Jonathon C. Scott, Kenneth A. Skach, Patricia L. Toccalino
2013, Scientific Investigations Report 2013-5030
The composition, occurrence, distribution, and possible toxicity of chemical mixtures in the environment are research concerns of the U.S. Geological Survey and others. The presence of specific chemical mixtures may serve as indicators of natural phenomena or human-caused events. Chemical mixtures may also have ecological, industrial, geochemical, or toxicological effects....
Variability common to first leaf dates and snowpack in the western conterminous United States
Gregory J. McCabe, Julio L. Betancourt, Gregory T. Pederson, Mark D. Schwartz
2013, Earth Interactions (17)
Singular value decomposition is used to identify the common variability in first leaf dates (FLDs) and 1 April snow water equivalent (SWE) for the western United States during the period 1900–2012. Results indicate two modes of joint variability that explain 57% of the variability in FLD and 69% of the...
Controls on recent Alaskan lake changes identified from water isotopes and remote sensing
Lesleigh Anderson, Jean Birks, Jennifer R. Rover, Nikki Guldager
2013, Geophysical Research Letters (40) 3413-3418
High-latitude lakes are important for terrestrial carbon dynamics and waterfowl habitat driving a need to better understand controls on lake area changes. To identify the existence and cause of recent lake area changes in the Yukon Flats, a region of discontinuous permafrost in north central Alaska, we evaluate remotely sensed imagery with lake water isotope compositions...
The National Water-Quality Assessment (NAWQA) Program planned monitoring and modeling activities for Texas, 2013–23
Patricia Ging
2013, Fact Sheet 2013-3038
The U.S. Geological Survey’s (USGS) National Water-Quality Assessment (NAWQA) Program was established by Congress in 1992 to answer the following question: What is the status of the Nation’s water quality and is it getting better or worse? Since 1992, NAWQA has been a primary source of nationally consistent data and...
Linear extension rates of massive corals from the Dry Tortugas National Park (DRTO), Florida
Adis Muslic, Jennifer A. Flannery, Christopher D. Reich, Daniel K. Umberger, Joseph M. Smoak, Richard Z. Poore
2013, Open-File Report 2013-1121
Colonies of three coral species, Montastraea faveolata, Diploria strigosa, and Siderastrea siderea, located in the Dry Tortugas National Park (DRTO), Florida, were sampled and analyzed to evaluate annual linear extension rates. Montastraea faveolata had the highest average linear extension and variability in (DRTO: C2 = 0.67 centimeters/year (cm yr-1) ± 0.04, B3 = 0.85 cm...
Source and transport of human enteric viruses in deep municipal water supply wells
Kenneth R. Bradbury, Mark A. Borchardt, Madeline Gotkowitz, Susan K. Spencer, Jun Zhu, Randall J. Hunt
2013, Environmental Science & Technology (47) 4096-4103
Until recently, few water utilities or researchers were aware of possible virus presence in deep aquifers and wells. During 2008 and 2009 we collected a time series of virus samples from six deep municipal water-supply wells. The wells range in depth from approximately 220 to 300 m and draw water...
Phylogeography and population genetic structure of double-crested cormorants (Phalacrocorax auritus)
Dacey Mercer, Susan M. Haig, Daniel D. Roby
2013, Conservation Genetics (14) 823-836
We examined the genetic structure of doublecrested cormorants (Phalacrocorax auritus) across their range in the United States and Canada. Sequences of the mitochondrial control region were analyzed for 248 cormorants from 23 breeding sites. Variation was also examined at eight microsatellite loci for 409 cormorants from the same sites. The mitochondrial...
