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Becker SM, Franz TE, Morris TC, Mullins B. Field Testing of Gamma-Spectroscopy Method for Soil Water Content Estimation in an Agricultural Field. SENSORS (BASEL, SWITZERLAND) 2024; 24:2223. [PMID: 38610435 PMCID: PMC11014223 DOI: 10.3390/s24072223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 03/25/2024] [Accepted: 03/28/2024] [Indexed: 04/14/2024]
Abstract
Gamma-ray spectroscopy (GRS) enables continuous estimation of soil water content (SWC) at the subfield scale with a noninvasive sensor. Hydrological applications, including hyper-resolution land surface models and precision agricultural decision making, could benefit greatly from such SWC information, but a gap exists between established theory and accurate estimation of SWC from GRS in the field. In response, we conducted a robust three-year field validation study at a well-instrumented agricultural site in Nebraska, United States. The study involved 27 gravimetric water content sampling campaigns in maize and soybean and 40K specific activity (Bq kg-1) measurements from a stationary GRS sensor. Our analysis showed that the current method for biomass water content correction is appropriate for our maize and soybean field but that the ratio of soil mass attenuation to water mass attenuation used in the theoretical equation must be adjusted to satisfactorily describe the field data. We propose a calibration equation with two free parameters: the theoretical 40K intensity in dry soil and a, which creates an "effective" mass attenuation ratio. Based on statistical analyses of our data set, we recommend calibrating the GRS sensor for SWC estimation using 10 profiles within the footprint and 5 calibration sampling campaigns to achieve a cross-validation root mean square error below 0.035 g g-1.
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Affiliation(s)
- Sophia M. Becker
- School of Natural Resources, University of Nebraska-Lincoln, Lincoln, NE 68503, USA; (T.E.F.); (T.C.M.)
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Bradford MA, Maynard DS, Crowther TW, Frankson PT, Mohan JE, Steinrueck C, Veen CGF, King JR, Warren RJ. Belowground community turnover accelerates the decomposition of standing dead wood. Ecology 2021; 102:e03484. [PMID: 34289121 DOI: 10.1002/ecy.3484] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 05/27/2021] [Indexed: 11/11/2022]
Abstract
Standing dead trees (snags) decompose more slowly than downed dead wood and provide critical habitat for many species. The rate at which snags fall therefore influences forest carbon dynamics and biodiversity. Fall rates correlate strongly with mean annual temperature, presumably because warmer climates facilitate faster wood decomposition and hence degradation of the structural stability of standing wood. These faster decomposition rates coincide with turnover from fungal-dominated wood decomposer communities in cooler forests to co-domination by fungi and termites in warmer regions. A key question for projecting forest dynamics is therefore whether temperature effects on wood decomposition arise primarily because warmer conditions facilitate faster decomposer metabolism, or are also influenced indirectly by belowground community turnover (e.g. termites exert additional influence beyond fungal-plus-bacterial mediated decomposition). To test between these possibilities, we simulate standing dead trees with untreated, wooden posts and follow them in the field across five years at 12 sites, before measuring buried, soil-air interface and aerial post sections to quantify wood decomposition and organism activities. High termite activities at the warmer sites are associated with rates of post fall that are 3-times higher than at the cooler sites. Termites primarily consume buried wood, with decomposition rates greatest where termite activities are highest. However, where higher microbial and termite activities co-occur, they appear to first compensate for one another and then slow decomposition rates at their highest activities, suggestive of interference competition. If the range of microbial- and termite co-domination of wood decomposer communities expands under climate warming, our data suggest that expansion will accelerate snag fall with consequent effects on forest carbon cycling and biodiversity in forests previously dominated by microbial decomposers.
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Affiliation(s)
- Mark A Bradford
- The Forest School, Yale School of the Environment, Yale University, 195 Prospect St, New Haven, CT, 06511, USA
| | - Daniel S Maynard
- Institute of Integrative Biology, ETH Zurich, Univeritätstrasse 16, 8006, Zürich, Switzerland
| | - Thomas W Crowther
- Institute of Integrative Biology, ETH Zurich, Univeritätstrasse 16, 8006, Zürich, Switzerland
| | - Paul T Frankson
- Odum School of Ecology, University of Georgia, Athens, GA, 30601, USA
| | | | | | - Ciska G F Veen
- Department of Terrestrial Ecology, Netherlands Institute of Ecology, PO Box 50, 6700 AB, Wageningen, The Netherlands
| | - Joshua R King
- Biology Department, University of Central Florida, 4110 Libra Drive, Orlando, FL, 32816, USA
| | - Robert J Warren
- Department of Biology, SUNY Buffalo State, 1300 Elmwood Avenue, Buffalo, NY, 14222, USA
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A Three-Dimensional Assessment of Soil δ13C in a Subtropical Savanna: Implications for Vegetation Change and Soil Carbon Dynamics. SOIL SYSTEMS 2019. [DOI: 10.3390/soilsystems3040073] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Tree/shrub encroachment into drylands is a geographically widespread vegetation change that often modifies soil organic carbon (SOC) storage and dynamics, and represents an important yet uncertain aspect of the global carbon (C) cycle. We quantified spatial patterns of soil δ13C to 1.2 m depth in a subtropical savanna to evaluate the magnitude and timing of woody encroachment, and its impacts on SOC dynamics. Woody encroachment dramatically altered soil δ13C spatial patterns throughout the profile; values were lowest in the interiors of woody patches, increased towards the peripheries of those patches, and reached highest values in the surrounding grasslands. Soil δ13C and 14C revealed this landscape was once dominated by C4 grasses. However, a rapid vegetation change occurred during the past 100–200 years, characterized by (1) the formation and expansion of woody patches across this landscape, and (2) increased C3 forb abundance within remnant grasslands. Tree/shrub encroachment has substantially increased SOC and the proportion of new SOC derived from C3 plants in the SOC pool. These findings support the emerging perspective that vegetation in many dryland ecosystems is undergoing dramatic and rapid increases in SOC storage, with implications for the C cycle at regional and global scales.
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Pedersen KB, Jensen PE, Ottosen LM, Barlindhaug J. Applying multivariate analysis for optimising the electrodialytic removal of Cu and Pb from shooting range soils. JOURNAL OF HAZARDOUS MATERIALS 2019; 368:869-876. [PMID: 30322811 DOI: 10.1016/j.jhazmat.2018.10.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 09/20/2018] [Accepted: 10/03/2018] [Indexed: 06/08/2023]
Abstract
Multivariate analysis was applied to simultaneously evaluate the influence of soil properties and experimental variables on electrodialytic removal of Cu and Pb from three shooting range soils. Both stationary and stirred set-ups in laboratory scale were tested, representing in-situ and ex-situ remediation conditions, respectively. Within the same experimental space, higher removal of the targeted metals, Cu and Pb, were observed in the stirred set-up (9-81%) compared to the stationary set-up (0-41%). Multivariate analysis (projections onto latent structures) revealed that the influence of soil type on the remediation efficiency was dependent on the metal and varied in the stationary and stirred set-ups. Optimising the removal of Cu by adjusting the experimental settings was easier to achieve in the stirred set-up and could be done by increasing the current density. Optimising the removal of Pb could be done by prolonging the treatment and in the stirred set-up also by increasing the current density.
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Affiliation(s)
- Kristine B Pedersen
- Akvaplan-niva AS, High North Research Centre for Climate and the Environment, Hjalmar Johansens Gate 14, 9007, Tromsø, Norway.
| | - Pernille E Jensen
- Arctic Technology Centre, Department of Civil Engineering, Technical University of Denmark, Building 118, 2800, Lyngby, Denmark
| | - Lisbeth M Ottosen
- Arctic Technology Centre, Department of Civil Engineering, Technical University of Denmark, Building 118, 2800, Lyngby, Denmark
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Consistent trade-offs in fungal trait expression across broad spatial scales. Nat Microbiol 2019; 4:846-853. [DOI: 10.1038/s41564-019-0361-5] [Citation(s) in RCA: 67] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Accepted: 01/06/2019] [Indexed: 12/27/2022]
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Wieder WR, Hartman MD, Sulman BN, Wang YP, Koven CD, Bonan GB. Carbon cycle confidence and uncertainty: Exploring variation among soil biogeochemical models. GLOBAL CHANGE BIOLOGY 2018; 24:1563-1579. [PMID: 29120516 DOI: 10.1111/gcb.13979] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 10/18/2017] [Indexed: 06/07/2023]
Abstract
Emerging insights into factors responsible for soil organic matter stabilization and decomposition are being applied in a variety of contexts, but new tools are needed to facilitate the understanding, evaluation, and improvement of soil biogeochemical theory and models at regional to global scales. To isolate the effects of model structural uncertainty on the global distribution of soil carbon stocks and turnover times we developed a soil biogeochemical testbed that forces three different soil models with consistent climate and plant productivity inputs. The models tested here include a first-order, microbial implicit approach (CASA-CNP), and two recently developed microbially explicit models that can be run at global scales (MIMICS and CORPSE). When forced with common environmental drivers, the soil models generated similar estimates of initial soil carbon stocks (roughly 1,400 Pg C globally, 0-100 cm), but each model shows a different functional relationship between mean annual temperature and inferred turnover times. Subsequently, the models made divergent projections about the fate of these soil carbon stocks over the 20th century, with models either gaining or losing over 20 Pg C globally between 1901 and 2010. Single-forcing experiments with changed inputs, temperature, and moisture suggest that uncertainty associated with freeze-thaw processes as well as soil textural effects on soil carbon stabilization were larger than direct temperature uncertainties among models. Finally, the models generated distinct projections about the timing and magnitude of seasonal heterotrophic respiration rates, again reflecting structural uncertainties that were related to environmental sensitivities and assumptions about physicochemical stabilization of soil organic matter. By providing a computationally tractable and numerically consistent framework to evaluate models we aim to better understand uncertainties among models and generate insights about factors regulating the turnover of soil organic matter.
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Affiliation(s)
- William R Wieder
- Institute of Arctic and Alpine Research, University of Colorado, Boulder, CO, USA
- Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
| | - Melannie D Hartman
- Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
- Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA
| | - Benjamin N Sulman
- Program in Atmospheric and Oceanic Sciences, Princeton University, Princeton, NJ, USA
| | - Ying-Ping Wang
- South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China
- CSIRO Oceans and Atmosphere, Aspendale, Vic., Australia
| | - Charles D Koven
- Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Gordon B Bonan
- Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, USA
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Mueller KE, Lodge AG, Roth AM, Whitfeld TJS, Hobbie SE, Reich PB. A tale of two studies: Detection and attribution of the impacts of invasive plants in observational surveys. J Appl Ecol 2018. [DOI: 10.1111/1365-2664.13075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Kevin E. Mueller
- Department of Forest Resources; University of Minnesota; St Paul MN USA
- Department of Biological, Geological and Environmental Sciences; Cleveland State University; Cleveland OH USA
| | - Alexandra G. Lodge
- Department of Forest Resources; University of Minnesota; St Paul MN USA
- Ecosystem Science and Management Department; Texas A&M University; College Station TX USA
| | - Alexander M. Roth
- Department of Forest Resources; University of Minnesota; St Paul MN USA
- Friends of the Mississippi River; St Paul MN USA
| | - Timothy J. S. Whitfeld
- Department of Forest Resources; University of Minnesota; St Paul MN USA
- Department of Ecology and Evolutionary Biology; Brown University; Providence RI USA
| | - Sarah E. Hobbie
- Department of Ecology, Evolution, and Behavior; University of Minnesota; St Paul MN USA
| | - Peter B. Reich
- Department of Forest Resources; University of Minnesota; St Paul MN USA
- Hawkesbury Institute for the Environment; Western Sydney University; Penrith NSW Australia
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A test of the hierarchical model of litter decomposition. Nat Ecol Evol 2017; 1:1836-1845. [DOI: 10.1038/s41559-017-0367-4] [Citation(s) in RCA: 129] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Accepted: 08/31/2017] [Indexed: 11/09/2022]
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Xu M, Wang Z, Zhao Y. Stratification ratio of soil organic carbon as an indicator of carbon sequestration and soil quality in ecological restoration. Restor Ecol 2017. [DOI: 10.1111/rec.12597] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Mingxiang Xu
- State Key Laboratory of Soil Erosion and Dry Land Farming on Loess Plateau; Northwest A & F University; 26 Xinong Road, Yangling Shaanxi 712100 China
| | - Zheng Wang
- Department of Geography, Global Environmental and Climate Change Center; McGill University; Montreal Quebec H3A 0B9 Canada
| | - Yunge Zhao
- State Key Laboratory of Soil Erosion and Dry Land Farming on Loess Plateau; Northwest A & F University; 26 Xinong Road, Yangling Shaanxi 712100 China
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Are Australian and United States Farmers Using Soil Information for Soil Health Management? SUSTAINABILITY 2016. [DOI: 10.3390/su8040304] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Richter DD, Billings SA. 'One physical system': Tansley's ecosystem as Earth's critical zone. THE NEW PHYTOLOGIST 2015; 206:900-912. [PMID: 25731586 DOI: 10.1111/nph.13338] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 01/08/2015] [Indexed: 06/04/2023]
Abstract
Integrative concepts of the biosphere, ecosystem, biogeocenosis and, recently, Earth's critical zone embrace scientific disciplines that link matter, energy and organisms in a systems-level understanding of our remarkable planet. Here, we assert the congruence of Tansley's (1935) venerable ecosystem concept of 'one physical system' with Earth science's critical zone. Ecosystems and critical zones are congruent across spatial-temporal scales from vegetation-clad weathering profiles and hillslopes, small catchments, landscapes, river basins, continents, to Earth's whole terrestrial surface. What may be less obvious is congruence in the vertical dimension. We use ecosystem metabolism to argue that full accounting of photosynthetically fixed carbon includes respiratory CO₂ and carbonic acid that propagate to the base of the critical zone itself. Although a small fraction of respiration, the downward diffusion of CO₂ helps determine rates of soil formation and, ultimately, ecosystem evolution and resilience. Because life in the upper portions of terrestrial ecosystems significantly affects biogeochemistry throughout weathering profiles, the lower boundaries of most terrestrial ecosystems have been demarcated at depths too shallow to permit a complete understanding of ecosystem structure and function. Opportunities abound to explore connections between upper and lower components of critical-zone ecosystems, between soils and streams in watersheds, and between plant-derived CO₂ and deep microbial communities and mineral weathering.
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Affiliation(s)
- Daniel deB Richter
- Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA
| | - Sharon A Billings
- Department of Ecology and Evolutionary Biology and Kansas Biological Survey, University of Kansas, Lawrence, KS, 66047, USA
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Experiments Are Revealing a Foundation Species: A Case Study of Eastern Hemlock (Tsuga canadensis). ACTA ACUST UNITED AC 2014. [DOI: 10.1155/2014/456904] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Foundation species are species that create and define particular ecosystems; control in large measure the distribution and abundance of associated flora and fauna; and modulate core ecosystem processes, such as energy flux and biogeochemical cycles. However, whether a particular species plays a foundational role in a system is not simply asserted. Rather, it is a hypothesis to be tested, and such tests are best done with large-scale, long-term manipulative experiments. The utility of such experiments is illustrated through a review of the Harvard Forest Hemlock Removal Experiment (HF-HeRE), a multidecadal, multihectare experiment designed to test the foundational role of eastern hemlock, Tsuga canadensis, in eastern North American forests. Experimental removal of T. canadensis has revealed that after 10 years, this species has pronounced, long-term effects on associated flora and fauna, but shorter-term effects on energy flux and nutrient cycles. We hypothesize that on century-long scales, slower changes in soil microbial associates will further alter ecosystem processes in T. canadensis stands. HF-HeRE may indeed continue for >100 years, but at such time scales, episodic disturbances and changes in regional climate and land cover can be expected to interact in novel ways with these forests and their foundation species.
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Spatial variability and stocks of soil organic carbon in the Gobi desert of Northwestern China. PLoS One 2014; 9:e93584. [PMID: 24733073 PMCID: PMC3986058 DOI: 10.1371/journal.pone.0093584] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Accepted: 03/05/2014] [Indexed: 11/23/2022] Open
Abstract
Soil organic carbon (SOC) plays an important role in improving soil properties and the C global cycle. Limited attention, though, has been given to assessing the spatial patterns and stocks of SOC in desert ecosystems. In this study, we quantitatively evaluated the spatial variability of SOC and its influencing factors and estimated SOC storage in a region (40 km2) of the Gobi desert. SOC exhibited a log-normal depth distribution with means of 1.6, 1.5, 1.4, and 1.4 g kg−1 for the 0–10, 10–20, 20–30, and 30–40 cm layers, respectively, and was moderately variable according to the coefficients of variation (37–42%). Variability of SOC increased as the sampling area expanded and could be well parameterized as a power function of the sampling area. Significant correlations were detected between SOC and soil physical properties, i.e. stone, sand, silt, and clay contents and soil bulk density. The relatively coarse fractions, i.e. sand, silt, and stone contents, had the largest effects on SOC variability. Experimental semivariograms of SOC were best fitted by exponential models. Nugget-to-sill ratios indicated a strong spatial dependence for SOC concentrations at all depths in the study area. The surface layer (0–10 cm) had the largest spatial dependency compared with the other layers. The mapping revealed a decreasing trend of SOC concentrations from south to north across this region of the Gobi desert, with higher levels close to an oasis and lower levels surrounded by mountains and near the desert. SOC density to depths of 20 and 40 cm for this 40 km2 area was estimated at 0.42 and 0.68 kg C m−2, respectively. This study provides an important contribution to understanding the role of the Gobi desert in the global carbon cycle.
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