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The USGS provides unbiased, objective, and impartial scientific information upon which our audiences, including resource managers, planners, and other entities, rely.
Browse more than 65,000 articles authored by our scientists over the past 100+ year history of the USGS and refine search by topic, location, year, and advanced search.
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Can the impact of canopy trees on soil and understory be altered using litter additions? Can the impact of canopy trees on soil and understory be altered using litter additions?
Trees can have large effects on soil nutrients in ways that alter succession, particularly in the case of nitrogen-(N)-fixing trees. In Hawaiʻi, forest restoration relies heavily on use of a native N-fixing tree, Acacia koa (koa), but this species increases soil-available N and likely facilitates competitive dominance of exotic pasture grasses. In contrast, Metrosideros polymorpha (‘ōhi...
Authors
Stephanie G. Yelenik, Evan M Rehm, Carla M. D’Antonio
Active neutron interrogation experiments and simulation verification using the SIngle-scintillator Neutron and Gamma-Ray spectrometer (SINGR) for geosciences Active neutron interrogation experiments and simulation verification using the SIngle-scintillator Neutron and Gamma-Ray spectrometer (SINGR) for geosciences
We present a new SIngle-scintillator Neutron and Gamma Ray spectrometer (SINGR) instrument for use with both passive and active measurement techniques. Here we discuss the application of SINGR for planetary exploration missions, however, hydrology, nuclear non-proliferation, and resource prospecting are all potential areas where the instrument could be applied. SINGR uses an elpasolite
Authors
Lena E. Heffern, Craig J. Hardgrove, Ann Parsons, E. B. Johnson, R. Starr, G. Stoddard, R. E. Blakeley, Thomas H. Prettyman, Travis S.J. Gabriel, H. Barnaby, J. Christian, M.A. Unzueta, C. Tate, Alynn Martin, J. Moersch
Central-West Siberian-breeding Bar-tailed Godwits (Limosa lapponica) segregate in two morphologically distinct flyway populations Central-West Siberian-breeding Bar-tailed Godwits (Limosa lapponica) segregate in two morphologically distinct flyway populations
Long-distance migratory species often include multiple breeding populations, with distinct migration routes, wintering areas and annual-cycle timing. Detailed knowledge on population structure and migratory connectivity provides the basis for studies on the evolution of migration strategies and for species conservation. Currently, five subspecies of Bar-tailed Godwits Limosa lapponica...
Authors
Roeland A. Bom, Jesse R. Conklin, Yvonne I. Verkuil, Jose A. Alves, Jimmy De Fouw, Anne Dekinga, Chris J. Hassell, Raymond H. G. Klaassen, Eldar Rakhimberdiev, Andy Y. Kwarteng, Afonso Rocha, Job ten Horn, T. Lee Tibbitts, Pavel S. Tomkovich, Reginald Victor, Theunis Piersma
Influence of permafrost type and site history on losses of permafrost carbon after thaw Influence of permafrost type and site history on losses of permafrost carbon after thaw
We quantified permafrost peat plateau and post-thaw carbon (C) stocks across a chronosequence in Interior Alaska to evaluate the amount of C lost with thaw. Macrofossil reconstructions revealed three stratigraphic layers of peat: (1) a base layer of fen/marsh peat, (2) peat from a forested peat plateau (with permafrost) and, (3) collapse-scar bog peat (at sites where permafrost thaw has...
Authors
Kristen L. Manies, Miriam C. Jones, Mark Waldrop, Mary-Catherine Leewis, Christopher C. Fuller, Robert S. Cornman, Kristen Hoefke
Retention and dimensional changes of evergreen brush piles within a flood control reservoir Retention and dimensional changes of evergreen brush piles within a flood control reservoir
Brush piles (i.e., trees and large woody debris) are often installed in reservoirs to supplement fish habitat. The retention and dimensional change of brush piles after installation is important information that can be used to maximize the effectiveness of this management action. We evaluated the retention and dimensional change of 70 eastern red cedar Juniperus virginiana and bald...
Authors
C.A. Aldridge, D.M. Norris, H.R. Hatcher, G. Coppola, M.E. Colvin, Leandro E. Miranda
Joint effects of climate, tree size, and year on annual tree growth derived using tree-ring records of ten globally distributed forests Joint effects of climate, tree size, and year on annual tree growth derived using tree-ring records of ten globally distributed forests
Tree rings provide an invaluable long-term record for understanding how climate and other drivers shape tree growth and forest productivity. However, conventional tree-ring analysis methods were not designed to simultaneously account for the effects of climate, tree size, and other drivers on individual growth, which has limited the potential to use tree rings to understand forest...
Authors
Kristina J. Anderson-Teixeira, Valentine Herrmann, Christy Rollinson, Bianca Gonzales, Erika B. Gonzalez-Akre, Neil Pederson, M. Ross Alexander, Craig D. Allen, Raquel Alfaro-Sanchez, Tala Awada, Jennifer L. Baltzer, Patrick J. Baker, Joseph D. Birch, Sarayudh Bunyavejchewin, Paolo Cherubini, Stewart J. Davies, Cameron Dow, Ryan Helcoski, Jakub Kaspar, James A. Lutz, Ellis Q. Margolis, Justin Maxwell, Sean M. McMahon, Camille Piponiot, Sabrina E. Russo, Pavel Šamonil, Anastasia E. Sniderhan, Alan J. Tepley, Ivana Vasickova, Mart Vlam, Pieter A. Zuidema
Habitat diversity influences puma (Puma concolor) diet in the Chihuahuan Desert Habitat diversity influences puma (Puma concolor) diet in the Chihuahuan Desert
Habitat heterogeneity and corresponding diversity in potential prey species should increase the diet breadth of generalist predators. Many previous studies describing puma Puma concolor diets in the arid regions of the southwestern United States were focused within largely xeric locations, overlooking the influence of heterogeneity created by riparian forests. Such habitat heterogeneity...
Authors
Charles H. Prude, James W. Cain
Landscape- and local- level variables affect monarchs in Midwest grasslands Landscape- and local- level variables affect monarchs in Midwest grasslands
Context
Authors
Anna Skye Bruce, Wayne E. Thogmartin, Chris Trosen, Karen Oberhauser, Claudio Gratton
Quantifying status and trends from monitoring surveys: Application to Pygmy Whitefish (Prosopium coulterii) in Lake Superior Quantifying status and trends from monitoring surveys: Application to Pygmy Whitefish (Prosopium coulterii) in Lake Superior
Population assessments of fish species often rely on data from surveys with different objectives, such as measuring biodiversity or community dynamics. These surveys often contain spatial–temporal dependencies that can greatly influence conclusions drawn from analyses. Pygmy whitefish (PWF, Prosopium coulterii) populations in Lake Superior were recently assessed as Threatened by the...
Authors
Adam S van der Lee, Mark R. Vinson, Marten A. Koops
A common garden super-experiment: An impossible dream to inspire possible synthesis A common garden super-experiment: An impossible dream to inspire possible synthesis
Global change threatens plant diversity and disrupts its interrelationship with ecosystem structure and function. This disruption in turn undermines confidence in the knowledge ecologists produce, and whether it will translate into multidisciplinary research settings or guide the effective management of natural lands.To address this challenge, ecology needs to consider the interactions...
Authors
Travis E. Huxman, Daniel E. Winkler, Kailen A. Mooney
Aquatic foods to nourish nations Aquatic foods to nourish nations
Despite contributing to healthy diets for billions of people, aquatic foods are often undervalued as a nutritional solution because their diversity is often reduced to the protein and energy value of a single food type (‘seafood’ or ‘fish’)1,2,3,4. Here we create a cohesive model that unites terrestrial foods with nearly 3,000 taxa of aquatic foods to understand the future impact of...
Authors
Christopher D. Golden, J. Zachary Koehn, Alon Shepon, Simone Passarelli, Christopher M. Free, Daniel Viana, Holger Matthey, Jacob G. Eurich, Jessica A. Gephart, Etienne Fluet-Chouinard, Elizabeth A. Nyboer, Abigail J. Lynch, Marian Kjellevold, Sabri Bromage, Pierre Charlebois, Manuel Barange, Stefania Vannuccini, Ling Cao, Kristin Kleisner, Eric Rimm, Goodarz Danaei, Camille DeDisto, Heather Kelahan, Kathryn J. Fiorella, David C. Little, Edward H. Allison, Jessica Fanzo, Shakuntala H. Thilsted
Lethal impacts of selenium counterbalance the potential reduction in mercury bioaccumulation for freshwater organisms☆ Lethal impacts of selenium counterbalance the potential reduction in mercury bioaccumulation for freshwater organisms☆
Mercury (Hg), a potent neurotoxic element, can biomagnify through food webs once converted into methylmercury (MeHg). Some studies have found that selenium (Se) exposure may reduce MeHg bioaccumulation and toxicity, though this pattern is not universal. Se itself can also be toxic at elevated levels. We experimentally manipulated the relative concentrations of dietary MeHg and Se (as
Authors
Jacqueline R. Gerson, Rebecca A. Consbrock, Collin A. Eagles-Smith, Emily S. Bernhardt, David Walters