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Most models of soil humic substances include a substantial component of aromatic C either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. We physically separated coarse (0.2–2.0 μm e.s.d.), medium (0.02–0.2 μm e.s.d.), and fine (> 0.02 μm e.s.d.) clay subfractions from three Midwestern soils and characterized the organic material associated with these subfractions using 13C-CPMAS-NMR, DTG, SEM-EDX, incubations, and radiocarbon age. Most of the C in the coarse clay subfraction was present as discrete particles (0.2–5 μm as seen in SEM images) of black carbon (BC) and consisted of approximately 60% aromatic C, with the remainder being a mixture...
Soil organic matter (SOM) biomarker methods were utilized in this study to investigate the responses of fungi and bacteria to freeze–thaw cycles (FTCs) and to examine freeze–thaw-induced changes in SOM composition and substrate availability. Unamended, grass-amended, and lignin-amended soil samples were subject to 10 laboratory FTCs. Three SOM fractions (free lipids, bound lipids, and lignin-derived phenols) with distinct composition, stability and source were examined with chemolysis and biomarker Gas Chromatography/Mass Spectrometry methods and the soil microbial community composition was monitored by phospholipid fatty acid (PLFA) analysis. Soil microbial respiration was also measured before and during freezing...
A major uncertainty in predicting long-term ecosystem C balance is whether stimulation of net primary production will be sustained in future atmospheric CO2 scenarios. Immobilization of nutrients (N in particular) in plant biomass and soil organic matter (SOM) provides negative feedbacks to plant growth and may lead to progressive N limitation (PNL) of plant response to CO2 enrichment. Soil microbes mediate N availability to plants by controlling litter decomposition and N transformations as well as dominating biological N fixation. CO2-induced changes in C inputs, plant nutrient demand and water use efficiency often have interactive and contrasting effects on microbes and microbially mediated N processes. One critical...
Widespread cheatgrass (Bromus tectorum L.) invasion represents a major shift in species dominance that may alter ecosystem processes across much of the western US. To investigate differences following such conversion, soil morphology and organic matter under cheatgrass-dominated and native shrub-steppe vegetation were compared by standard soil analysis procedures at seven paired sites in Idaho and Utah. Results suggest that, following conversion to cheatgrass dominance, increased porosity and labile organic inputs enhance microbial decomposition in near-surface horizons beneath cheatgrass compared to adjacent soils under native vegetation. Enhanced decomposition could result in depletion of long-term SOM, leading...
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Winter climate change has the potential to have a large impact on coastal wetlands in the southeastern U.S. Warmer winter temperatures and reductions in the intensity of freeze events would likely lead to mangrove forest range expansion and salt marsh displacement in parts of the U.S. Gulf of Mexico and Atlantic coast. The objective of this research was to better understand some of the ecological implications of mangrove forest migration and salt marsh displacement. The potential ecological effects of mangrove migration are diverse ranging from important biotic impacts (e.g., coastal fisheries, land bird migration; colonial nesting wading birds) to ecosystem stability (e.g., response to sea level rise and drought;...
Nitric oxide (NO) is a relatively short-lived trace gas that reacts with oxygen in the troposphere to produce the air pollutant ozone. It also reacts with water vapor to form nitric and nitrous acids, which acidify precipitation and increase N deposition. Models currently used to predict soil NO fluxes are based on the assumption that NO flux is proportional to the gross rate of nitrification or N mineralization; however, this assumption has not been tested because of the difficulty in measuring gross N-cycling rates in situ. We measured soil NO fluxes, gross and net N-cycling rates, and a variety of other soil characteristics in the forest floor and intact soil cores at nine undisturbed forest and rangeland ecosystems...
Three mixed prairie sites at Mandan, N.D. were grazed heavily (0.9 ha ), moderately (2.6 ha ), or left ungrazed (exclosure) since 1916. These sites provided treatments to study the effects of long-term grazing on soil organic carbon and nitrogen content and to relate changes in soil carbon and nitrogen to grazing induced changes in species composition. Blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Griffiths] accounted for the greatest change in species composition for both grazing treatments. Relative foliar cover of blue grama was 25% in 1916 and 86% in 1994 in the heavily grazed pasture and 15% in 1916 to 16% in 1994 in the moderately grazed pasture. Total soil nitrogen content was higher in the exclosure (1.44...
Soil organic matter (SOM) biomarker methods were utilized in this study to investigate the responses of fungi and bacteria to freeze?thaw cycles (FTCs) and to examine freeze?thaw-induced changes in SOM composition and substrate availability. Unamended, grass-amended, and lignin-amended soil samples were subject to 10 laboratory FTCs. Three SOM fractions (free lipids, bound lipids, and lignin-derived phenols) with distinct composition, stability and source were examined with chemolysis and biomarker Gas Chromatography/Mass Spectrometry methods and the soil microbial community composition was monitored by phospholipid fatty acid (PLFA) analysis. Soil microbial respiration was also measured before and during freezing...
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This dataset contains measurements of chemical concentrations of soil samples representing 28 headwater drainage basins completely within the Adirondack Park of New York State (ADK Park), one basin partially in the ADK Park, and one watershed 2 kilometers from the ADK Park boundary. Seven of these watersheds have been sampled 2 or 3 times over periods of 12 to 22 years. Soil samples were collected from pit faces exposed by shoveling. Total mass of organic matter, carbon and nitrogen in the forest floor are also presented for 16 headwater drainage basins in the ADK Park. Forest floor mass data were determined from samples collected with soil corers. The presented data are organized by six projects: the Adirondack...
Categories: Data, Data Release - Revised; Types: ArcGIS REST Map Service, ArcGIS Service Definition, Downloadable, Map Service; Tags: Adirondack Park, Adirondack Park, New York, Ambient Monitoring, B horizon, B horizon, All tags...
This paper discusses the important limitations in several areas of element interaction research and highlights the discrepancies between model formulations and observable ecosystem properties, including carbon dynamics in soils and element ratios and threshold effects. Some difficulties in sampling of individual species within microbial communities and in determining the flexibility of microbial stoichiometry are discussed. Also covered are the new approaches and recent advancements in element cycling research, e.g., resolving the chemical identity of element observations, element analysis for individuals and species, and scaling element interactions from sites to regions. Finally, some elements of a proposed experimental...
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The sustainability of coastal wetlands largely hinges on their ability to accrue elevation capital at a rate that equals or exceeds relative sea-level rise. A better understanding of these processes is needed to accurately assess the sustainability of these landscapes, and to predict their response to restoration measures such as sediment delivery through river diversions.
Soil organic matter (SOM) biomarker methods were utilized in this study to investigate the responses of fungi and bacteria to freeze?thaw cycles (FTCs) and to examine freeze?thaw-induced changes in SOM composition and substrate availability. Unamended, grass-amended, and lignin-amended soil samples were subject to 10 laboratory FTCs. Three SOM fractions (free lipids, bound lipids, and lignin-derived phenols) with distinct composition, stability and source were examined with chemolysis and biomarker Gas Chromatography/Mass Spectrometry methods and the soil microbial community composition was monitored by phospholipid fatty acid (PLFA) analysis. Soil microbial respiration was also measured before and during freezing...
Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms...
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A better understanding of the potential of climate change to affect carbon dynamics in wetlands can be gained through the study of plant decomposition and soil organic matter trends across continental gradients. This study from 2007 and 2011 examines patterns of wood, leaf and cloth decomposition, as well as soil organic matter storage in Taxodium distichum (T. distichum) swamps along the Mississippi River Alluvial Valley (MRAV) and the northern Gulf of Mexico (GOM) in North America.
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This dataset contains vertical profiles of soil bulk density, percent organic matter, percent total carbon and cesium-137 activity from the surface down to 50-60 cm deep at 25 marsh locations across Breton Sound basin, Louisiana. These data will provide information related to rates of vertical accretion, organic and mineral accumulation and carbon burial in wetland soils across a large portion of the Mississippi River delta plain.
Analyses of carbon isotope ratios (?13C) in soil organic matter (SOM) and soil respired CO2 provide insights into dynamics of the carbon cycle. ?13C analyses do not provide direct measures of soil CO2 efflux rates but are useful as a constraint in carbon cycle models. In many cases, ?13C analyses allow the identification of components of soil CO2 efflux as well as the relative contribution of soil to overall ecosystem CO2 fluxes. ?13C values provide a unique tool for quantifying historical shifts between C3 and C4 ecosystems over decadal to millennial time scales, which are relevant to climate change and land-use change issues. We identify the need to distinguish between ?13C analyses of SOM and those of soil CO2...
Aiming at an improved understanding of the conditional nature of soil organic matter stability, we present an overview of (1) biotic strategies and (2) ecological processes by which decomposer organisms gain access to, or are prevented from metabolising soil organic resources. The biotic strategies discussed comprise well-known activities, such as the release of exo-enzymes, the mechanical crushing of organic residues, the bioturbation of soil mass, and the fixation of carbon in the living biomass. The ecological processes described have received less attention regarding their importance in prolonging the persistence of soil organic matter. Model calculations illustrate that cell energy demand forces micro-organisms...
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The recent completion of the US Army Corps of Engineers (USACE) Hurricane and Storm Damage Risk Reduction System (HSDRRS) for New Orleans has effectively blocked surface water exchange between Bayou Sauvage National Wildlife Refuge (BSNWR) and the surrounding Lake(s) Pontchartrain and Borgne and the Gulf of Mexico to which it was once connected. Monitoring changes in hydrology, water quality, bird habitat variability, and resident waterbird and nekton communities within BSNWR is important to the long-term sustainability of these aquatic resources for use by visitors and aquatic life in these habitats. In particular, landscape and hydrologic modifications from management and restoration projects in southeastern Louisiana...
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The northern Gulf of Mexico coast spans two major climate gradients and represents an excellent natural laboratory for developing climate-influenced ecological models. In this project, we used these zones of remarkable transition to develop macroclimate-based models for quantifying the regional responses of coastal wetland ecosystems to climate variation. In addition to providing important fish and wildlife habitat and supporting coastal food webs, these coastal wetlands provide many ecosystem goods and services including clean water, stable coastlines, food, recreational opportunities, and stored carbon. Our objective was to examine and forecast the effects of macroclimatic drivers on wetland ecosystem structure...
We conducted a study to evaluate the relative importance of topography, grazing, the location of individual plants (microsite), and plant species in controlling the spatial variability of soil organic matter in shortgrass steppe ecosystems. We found that the largest spatial variation occurs in concert with topography and with microsite-scale heterogeneity, with relatively little spatial variability due to grazing or to plant species. Total soil C and N, coarse and fine particulate organic matter C and N, and potentially mineralizable C were significantly affected by topography, with higher levels in toeslope positions than in midslopes or summits. Soils beneath individual plants (Bouteloua gracilis and Opuntia polyacantha)...
map background search result map search result map Laboratory Notes - Scanned Laboratory Notebook Pages for the following project - Ecological implications of mangrove forest migration in the southeastern US (2012-2-13) U.S. Gulf of Mexico coast (TX, MS, AL, and FL) Macroclimate Soil Data (2013-2014) Soil properties, soil radioisotope activity, and end-of-season belowground biomass across Barataria basin wetlands (2016) Trends in organic matter in baldcypress swamps of the southeastern United States: 2007-2011 Adirondack New York soil chemistry data, 1992-2017 (ver. 1.1, December 2020) Soil properties and soil radioisotope activity across Breton Sound basin wetlands (2008-2013) Wetland elevation and soil characteristics across Bayou Sauvage National Wildlife Refuge (2020-2021) Wetland elevation and soil characteristics across Bayou Sauvage National Wildlife Refuge (2020-2021) Soil properties and soil radioisotope activity across Breton Sound basin wetlands (2008-2013) Soil properties, soil radioisotope activity, and end-of-season belowground biomass across Barataria basin wetlands (2016) Adirondack New York soil chemistry data, 1992-2017 (ver. 1.1, December 2020) Laboratory Notes - Scanned Laboratory Notebook Pages for the following project - Ecological implications of mangrove forest migration in the southeastern US (2012-2-13) U.S. Gulf of Mexico coast (TX, MS, AL, and FL) Macroclimate Soil Data (2013-2014) Trends in organic matter in baldcypress swamps of the southeastern United States: 2007-2011