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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.

Filter Total Items: 74362

Carbon isotope trends across a century of herbarium specimens suggest CO2 fertilization of C4 grasses.

Increasing atmospheric CO2 is changing the dynamics of tropical savanna vegetation. C3 trees and grasses are known to experience CO2 fertilization, whereas responses to CO2 by C4 grasses are more ambiguous.Here, we sample stable carbon isotope trends in herbarium collections of South African C4 and C3 grasses to reconstruct 13C discrimination.We found that C3 grasses showed no trends in 13C discri
Authors
Isa del Toro, Madelon Florence Case, Allison Karp, Jasper Slingsby, A. Carla Staver

Thermal transfer rate is slower in bigger fish: How does body size affect response time of small, implantable temperature recording tags?

The recent miniaturisation of implantable temperature recording tags has made measuring the water temperatures fish experience in the wild possible, but there may be a body size-dependent delay in implanted tag response time to changes in external temperature. To determine whether fish body size affects the response rate of implanted temperature tags, we implanted 20 Salvelinus fontinalis (127–228
Authors
Matthew J. O'Donnell, Amy M. Regish, Stephen D. McCormick, Benjamin Letcher

Explosive 2018 eruptions at Kīlauea driven by a collapse-induced stomp-rocket mechanism

Explosive volcanic eruptions produce hazardous atmospheric plumes composed of tephra particles, hot gas and entrained air. Such eruptions are generally driven by magmatic fragmentation or steam expansion. However, an eruption mechanism outside this phreatic–magmatic spectrum was suggested by a sequence of 12 explosive eruptions in May 2018 at Kīlauea, Hawaii, that occurred during the early stages
Authors
Joshua Allen Crozier, Josef Dufek, Leif Karlstrom, Kyle R. Anderson, Ryan Cain Cahalan, Weston Thelen, Mary Catherine Benage, Chao Liang

Impact of Hurricane Irma on coral reef sediment redistribution at Looe Key Reef, Florida, USA

Understanding event-driven sediment transport in coral reef environments is essential to assessing impacts on reef species, habitats, restoration, and mitigation, yet a global knowledge gap remains due to limited quantitative studies. Hurricane Irma made landfall in the Lower Florida Keys with sustained 209 km h−1 winds and waves greater than 8 m on 10 September 2017, directly impacting the Florid
Authors
Kimberly Yates, Zachery Fehr, Selena Anne-Marie Johnson, David G. Zawada

Structural heterogeneity predicts ecological resistance and resilience to wildfire in arid shrublands

ContextDynamic feedbacks between physical structure and ecological function drive ecosystem productivity, resilience, and biodiversity maintenance. Detailed maps of canopy structure enable comprehensive evaluations of structure–function relationships. However, these relationships are scale-dependent, and identifying relevant spatial scales to link structure to function remains challenging.Objectiv
Authors
Andrii Zaiats, Megan E Cattau, David Pilliod, Rongsong Liu, Patricia Kaye T. Dumandan, Ahmad Hojatimalekshah, Donna M. Delparte, Trevor Caughlin

Milkweed and floral resource availability for monarch butterflies (Danaus plexippus) in the United States

The global decline of pollinators, particularly insects, underscores the importance of enhanced monitoring of their populations and habitats. However, monitoring some pollinator habitat is challenging due to widespread species distributions and shifts in habitat requirements through seasons and life stages. The monarch butterfly (Danaus plexippus), a migratory insect pollinator that breeds widely
Authors
Laura Lukens, Jennifer Thieme, Wayne E. Thogmartin

Declining groundwater storage expected to amplify mountain streamflow reductions in a warmer world

Groundwater interactions with mountain streams are often simplified in model projections, potentially leading to inaccurate estimates of streamflow response to climate change. Here, using a high-resolution, integrated hydrological model extending 400 m into the subsurface, we find groundwater an important and stable source of historical streamflow in a mountainous watershed of the Colorado River.
Authors
Rosemary W.H. Carroll, Richard G. Niswonger, Craig Ulrich, Charuleka Varadharajan, Erica Siirila-Woodburn, Kenneth H. Williams

Browsing the literature

For this edition of Browsing the Literature, we have two new papers from Rangeland Ecology & Management, a series of basic ecology papers with an international scope from journals such as the Proceedings of the National Academy of Sciences (USA), Science, and Nature, and several papers advancing our understanding of drought and carbon at global scales. Additionally, several papers on sagebrush-st
Authors
Matthew Germino

Does the extent of glacial cover across watersheds and discharge periods affect dietary resource use of nearshore fishes in the Northern Gulf of Alaska?

Northern high-latitude glaciers impact nearshore marine ecosystems through the discharge of cold and fresh waters, including nutrients and organic matter. Fishes are important integrators of ecosystem processes and hold key positions in the transfer of energy to higher trophic positions in such systems. This study used a natural gradient in space and time, including watershed glacial cover (0–60%)
Authors
Lindsey Stadler, Kristen Gorman, Vanessa R. von Biela, Andrew C. Seitz, Katrin Iken

How to select an objective function using information theory

In machine learning or scientific computing, model performance is measured with an objective function. But why choose one objective over another? According to the information-theoretic paradigm, the “best” objective function is whichever minimizes information loss. To evaluate different objectives, transform them into likelihoods. The ratios of these likelihoods represent how strongly we should pr
Authors
Timothy O. Hodson, Thomas M. Over, Smith Tyler, Lucy A. Marshall

Biodiversity loss reduces global terrestrial carbon storage

Natural ecosystems store large amounts of carbon globally, as organisms absorb carbon from the atmosphere to build large, long-lasting, or slow-decaying structures such as tree bark or root systems. An ecosystem’s carbon sequestration potential is tightly linked to its biological diversity. Yet when considering future projections, many carbon sequestration models fail to account for the role biodi
Authors
Sarah R. Weiskopf, Forest Isbell, Maria Isabel Arce-Plata, Moreno Di Marco, Mike Harfoot, Justin A. Johnson, Susannah B. Lerman, Brian W. Miller, Toni Lyn Morelli, Akira S. Mori, Ensheng Weng, Simon Ferrier

Earthquake relocations delineate discrete a fault network and deformation corridor throughout Southeast Alaska and Southwest Yukon

Deformation in southeastern Alaska and southwest Yukon is governed by the subduction and translation of the Pacific-Yakutat plates relative to the North American plate in the St. Elias region. Despite notable historical seismicity and major regional faults, studies of the region between the Fairweather and Denali faults are complicated by glacial coverage and the remote setting. In the last decade
Authors
Katherine M. Biegel, Jeremy M. Gosselin, Jan Dettmer, Maurice Colpron, Eva Enkelmann, Jonathan Caine