David G. Williams

University of Wyoming

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Elise Pendall

Western Sydney University

Travis E. Huxman

University of California, Irvine

Kevin R. Hultine

Desert Botanical Garden

Russell L. Scott

Southwest Watershed Research Center

Jake F. Weltzin

United States Geological Survey

Nathan B. English

Central Queensland University

Jack A. Morgan

Agricultural Research Service - Plains Area

Dana M. Blumenthal

Agricultural Research Service - Plains Area

David L. Dettman

University of Arizona

Víctor Resco de Dios

Universitat de Lleida

Cooperative Institutions

University of Arizona

University of Wyoming

Agricultural Research Service

United States Department of Agriculture

University of Utah

Centre National de la Recherche Scientifique

Ecological Society of America

Colorado State University

Wyoming Department of Education

Centre d'Études Spatiales de la Biosphère

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Shrub encroachment alters sensitivity of soil respiration to temperature and moisture

Journal of Geophysical Research Atmospheres (2011)

Jessica M. Cable G. Barron-Gafford Kiona Ogle Mitchell Pavao‐Zuckerman Russell L. Scott

A greater abundance of shrubs in semiarid grasslands affects the spatial patterns of soil temperature, moisture, and litter, resulting in fertile islands with potentially enhanced soil metabolic activity. The goal of this study was to quantify the microsite specificity of soil respiration in a semiarid riparian ecosystem experiencing shrub encroachment. We quantified the response of soil respiration to different microsite conditions created by big mesquite shrubs (near the trunk and the canopy edge), medium‐sized mesquite, sacaton bunchgrasses, and open spaces. We hypothesized that soil respiration would be more temperature sensitive and less moisture sensitive and have a greater magnitude in shrub microsites compared with grass and open microsites. Field and incubation soil respiration data were simultaneously analyzed in a Bayesian framework to quantify the microsite‐specific temperature and moisture sensitivities and magnitude of respiration. The analysis showed that shrub expansion increases the heterogeneity of respiration. Respiration has greater temperature sensitivity near the shrub canopy edge, and respiration rates are higher overall under big mesquite compared with those of the other microsites. Respiration in the microsites beneath medium‐sized mesquites does not behave like a downscaled version of big mesquite microsites. The grass microsites show more similarity to big mesquite microsites than medium‐sized shrubs. This study shows there can be a great deal of fine‐scale spatial heterogeneity that accompanies shifts in vegetation structure. Such complexity presents a challenge in scaling soil respiration fluxes to the landscape for systems experiencing shrub encroachment, but quantifying this complexity is significantly important in determining overall ecosystem metabolic behavior.

Microsite

Soil respiration

10.1029/2011jg001757

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Citations (38)

Oxygen isotopes in cellulose identify source water for archaeological maize in the American Southwest

Journal of Archaeological Science (2005)

David G. Williams Joan Brenner Coltrain Michael J. Lott Nathan B. English James R. Ehleringer

δ18O

10.1016/j.jas.2005.01.008

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Citations (39)

Soil N enrichment mediates carbon allocation through respiration in a dominant grass during drought

Functional Ecology (2022)

Bo Meng Junqin Li Yuan Yao Jesse B. Nippert David G. Williams

Abstract Carbon (C) allocation strategy plays a critical role in plant adaptability, which are also important to assess the productivity stability under environmental change. Based on optimal partitioning theory, we asked two questions: (1) How is plant C allocation within tissues affected by nutrient enrichment (N addition)? And (2) does long‐term N addition alter how plants allocate C under drought? To address these questions, we conducted a greenhouse experiment using the widespread perennial C 3 grass, Leymus chinensis , under four treatments: ‘Watered’, ‘Dry’, ‘Watered + N’ and ‘Dry + N’. 13 CO 2 pulse labelling was used to trace C transport through the plant–soil system. We found that drought and N addition resulted in additive effects on C allocation. Greater above‐ground biomass under N addition resulted in higher C loss via above‐ground plant respiration, even under drought, which plays a more important role in the adjustment of root:shoot ratio than does the trade‐off between above‐ and below‐ground organs. Compared to the concept of active phenotype adjustment for maximized growth rate in traditional optimal partitioning theory, our results imply that pre‐drought allometry, which changes under long‐term resource addition, also determines how plants respond to drought and their adaptability to changing environmental conditions. Read the free Plain Language Summary for this article on the Journal blog.

Adaptability

10.1111/1365-2435.14033

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Multi-wavelength synchronous pulse burst generation with a wavelength selective switch

Optics Express (2008)

M.A.F. Roelens J. A. Bolger David G. Williams Benjamin J. Eggleton

We demonstrate simultaneous pulse-shaping at different ports of a rapidly tunable wavelength selective switch at a base rate of 40 GHz, based on Fourier-domain pulse shaping. Various pulse bursts are generated and accurately characterized with a linear spectrographic method.

10.1364/oe.16.010152

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The Future of Large‐Scale Stable Isotope Networks

Deleted Journal (2007)

Debbie Hemming Howard Griffiths Neil J. Loader Alina Marca Iain Robertson

Funding for a large-scale ecosystem research has been notoriously difficult to secure and sustain over more than a few years. Yet it is this information that is, and will become even more vital in order to understand and tackle global environmental changes and their impacts on societies. The measurements of stable isotope ratios present in the important elements of life (hydrogen, carbon, oxygen, nitrogen, and sulphur) provide unique information on the structure and processes associated with ecosystem and biome functioning. To sustain large-scale isotopic monitoring into the future, it is important to identify the key advantages of these networks, particularly when combined with socioeconomic indicators and to explore how these advantages may be maximized in order to secure long-term funding. This chapter addresses these points by giving a brief overview of existing large-scale stable isotope networks, emphasizing some of the key information available from these and discussing the possible application of these data to key international policy issues. While the importance of targeting research toward the current international policy agenda is emphasized, it is also considered essential to balance this with fundamental research that provides vision toward the future potential applications of large-scale isotope data and a focus for the development of new technologies that introduce novel and more accurate information. By successfully integrating these aspects, it is hoped that large-scale stable isotope networks will be an important part of a well-developed and vibrant ecological research field that will be sustained into the future.

Biome

10.1016/s1936-7961(07)01023-8

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A system for scanning data from remote sensing applications when recorded on photographic emulsion

David G. Williams

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Controls on ecosystem respiration in a semi-arid watershed: seasonality and woody plant encroachment

AGU Spring Meeting Abstracts (2005)

J. Cable Daniel L. Potts Russell L. Scott David G. Williams D. C. Goodrich

Seasonality

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Isotopes Reveal Sources and Sinks of Trace Gases

Ecology (2005)

David G. Williams

TRACE (psycholinguistics)

Trace gas

10.1890/0012-9658(2005)86[3131:irsaso]2.0.co;2

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Characterization of forest recovery from fire using Landsat and SAR data

Guoqing Sun L. E. Rocchio J. G. Masek David G. Williams K.J. Ranson

The Forest fire during May 6-June 4, 1987 in Northeastern China burned 1.14 million hectares of forest and nearly 25 million cubic meters of timber. Landsat (5 and 7) and radar data (ERS and JERS-1) in combination with field measurements, were analyzed in terms of forest destruction and recovery and the results were evaluated. Temporal Landsat data enabled the identification of burned regions and the characterization of forest recovery, but sensitivity after 10 years was gradually lost. While the 1993 (and later) C-band SAR data from ERS cannot identify the fire scars, the 1997 JERS-1 L-band data can be used to characterize the burned area.

Forest structure

10.1109/igarss.2002.1025780

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Mid- and long-chain leaf wax δ2H values in modern plants and lake sediments from mid-latitude North America

Geochimica et Cosmochimica Acta (2022)

Ioana C. Stefanescu Chandelle Macdonald Craig S. Cook David G. Williams Bryan N. Shuman

10.1016/j.gca.2022.11.001

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Citations (5)