Earth Sciences Commons^™

Minerals In The Rhizosphere: Overlooked Mediators Of Soil Nitrogen Availability To Plants And Microbes, Andrea Jilling, Marco Keiluweit, Alexandra R. Contosta, Serita D. Frey, Joshua Schimel, Jorg Schnecker, Richard G. Smith, Lisa Tiemann, A. Stuart Grandy

Faculty Publications

Despite decades of research progress, ecologists are still debating which pools and fluxes provide nitrogen (N) to plants and soil microbes across different ecosystems. Depolymerization of soil organic N is recognized as the rate-limiting step in the production of bioavailable N, and it is generally assumed that detrital N is the main source. However, in many mineral soils, detrital polymers constitute a minor fraction of total soil organic N. The majority of organic N is associated with clay-sized particles where physicochemical interactions may limit the accessibility of N-containing compounds. Although mineral-associated organic matter (MAOM) has historically been considered a critical, …

Physical Processes Dictate Early Biogeochemical Dynamics Of Soil Pyrogenic Organic Matter In A Subtropical Forest Ecosystem, Jason Stuart, Russell Anderson, Patrick Lazzarino, Kevin A. Kuehn, Omar R. Harvey

Faculty Publications

Quantifying links between pyOM dynamics, environmental factors and processes is central to predicting ecosystem function and response to future perturbations. In this study, changes in carbon (TC), nitrogen (TN), pH, and relative recalcitrance (R50) for pineand cordgrass-derived pyOM were measured at 3–6 weeks intervals throughout the first year of burial in the soil. Objectives were to (1) identify key environmental factors and processes driving early-stage pyOM dynamics, and (2) develop quantitative relationships between environmental factors and observed changes in pyOM properties. The study was conducted in sandy soils of a forested ecosystem within the Longleaf pine range of the United …

Twinning Strains In Synfolding Calcite, Proterozoic Sinian System, China, John P. Craddock, Junlai Liu, Yuanyuan Zheng

Faculty Publications

Synfolding calcite was precipitated between layers of Neoproterozoic sandy dolomite and striated parallel to the fold axis of an open anticline with a shallow plunge during folding. The fold had limb dips of 45° and plunged 20° to the south. The synfolding calcite had sub-horizontal grooves that trended parallel to the fold. Limb-hinge-limb calcite samples (3 samples; n = 100 grains) preserved a layer-parallel shortening strain that trended at an acute (45°) angle to the trend of the fold axis and fold lineations. Extension axes were vertical and there was no strain overprint (low NEVs). Shortening strain magnitudes were −2.9% …

Unveiling The Enigma Of Refractory Carbon In The Ocean, Nianzhi Jiao, Ruanhong Cai, Qiang Zheng, Kai Tang, Jihua Liu, Fangkue Jiao, Douglas Wallace, Feng Chen, Chao Li, Rudolf Amann, Ronald Benner, Farooq Azam

Faculty Publications

No abstract provided.

Deeply-Sourced Formate Fuels Sulfate Reducers But Not Methanogens At Lost City Hydrothermal Field, Susan Q. Lang, Gretchen L. Früh-Green, Stefano M. Bernasconi, William J. Brazelton, Matthew O. Schrenk, Julia M. Mcgonigle

Faculty Publications

Hydrogen produced during water-rock serpentinization reactions can drive the synthesis of organic compounds both biotically and abiotically. We investigated abiotic carbon production and microbial metabolic pathways at the high energy but low diversity serpentinite-hosted Lost City hydrothermal field. Compound-specific 14C data demonstrates that formate is mantle-derived and abiotic in some locations and has an additional, seawater-derived component in others. Lipids produced by the dominant member of the archaeal community, the Lost City Methanosarcinales, largely lack 14C, but metagenomic evidence suggests they cannot use formate for methanogenesis. Instead, sulfate-reducing bacteria may be the primary consumers of formate in Lost City chimneys. …

Hydrothermal Stamp On The Oceans, Susan Q. Lang

Faculty Publications

The composition of the oceans is altered by hydrothermal circulation. These chemical factories sustain microbial life, which in turn alters the chemistry of the fuids that enter the ocean. A decade of research details this complex interchange.

Unconfined Hypogene Evaporite Karst: West Texas And Southeastern New Mexico, Usa, Kevin W. Stafford, Jon T. Ehrhart, Adam F. Majzoub, Jessica M. Shields, Wesley A. Brown

Faculty Publications

Diverse karst phenomena occur throughout the Gypsum Plain where the Castile Formation crops out over ~1800 km² in West Texas and southeastern New Mexico. Hypergene karst is extensive and widespread, while traditional hypogene karst manifestations (both caves and intrastratal dissolution) occur in high frequency in the western outcrop region where surface denudation has been the greatest so as to induce surficial breaching. Unconfined hypogene karst occurrences have been recently identified, including two general variations: 1) artesian-like discharge features; and 2) venting structures. Artesian-like discharge features arise at surficially-breached hypogene caves and through high permeability regions on the margins of …

Soil Carbon Cycling Proxies: Understanding Their Critical Role In Predicting Climate Change Feedbacks, Vanessa L. Bailey, Ben Bond-Lamberty, Kristen M. Deangelis, A. Stuart Grandy, Christine V. Hawkes, Kate Heckman, Kate Lajtha, Richard P. Phillips, Benjamin N. Sulman, Katherine E. O. Todd-Brown, Matthew D. Wallenstein

Faculty Publications

The complexity of processes and interactions that drive soil C dynamics necessitate the use of proxy variables to represent soil characteristics that cannot be directly measured (correlative proxies), or that aggregate information about multiple soil characteristics into one variable (integrative proxies). These proxies have proven useful for understanding the soil C cycle, which is highly variable in both space and time, and are now being used to make predictions of the fate and persistence of C under future climate scenarios. However, the C pools and processes that proxies represent must be thoughtfully considered in order to minimize uncertainties in empirical …

Fungal Community Homogenization, Shift In Dominant Trophic Guild, And Appearance Of Novel Taxa With Biotic Invasion, Mark A. Anthony, Serita D. Frey, Kristina A. Stinson

Faculty Publications

Invasion by non-native plants may fundamentally restructure the soil fungal community. The invasive plant, Alliaria petiolata, produces secondary compounds suppressive to mycorrhizal fungi and may therefore be expected to have generally negative effects on other components of the fungal community. Here, we compared fungal biomass, diversity, community composition, and the relative abundance of fungal trophic guilds, along with edaphic properties of soils collected from uninvaded and invaded plots across six temperate forests. Invaded plots were differentiated from uninvaded plots by lower variation in fungal community composition (beta diversity) and soil properties, higher fungal richness and community evenness (alpha diversity), and …

Highly Variable Recurrence Of Tsunamis In The 7,400 Years Before The 2004 Indian Ocean Tsunami, Charles M. Rubin, Benjamin P. Horton, Kerry Sieh, Jessica E. Pilarczyk, Patrick Daly, Nazli Ismail, Andrew C. Parnell

Faculty Publications

The devastating 2004 Indian Ocean tsunami caught millions of coastal residents and the scientific community off-guard. Subsequent research in the Indian Ocean basin has identified prehistoric tsunamis, but the timing and recurrence intervals of such events are uncertain. Here we present an extraordinary 7,400 year stratigraphic sequence of prehistoric tsunami deposits from a coastal cave in Aceh, Indonesia. This record demonstrates that at least 11 prehistoric tsunamis struck the Aceh coast between 7,400 and 2,900 years ago. The average time period between tsunamis is about 450 years with intervals ranging from a long, dormant period of over 2,000 years, to …

The Potential Effects Of Percolating Snowmelt On Palynological Records From Firn And Glacier Ice, Michael E. Ewin, Carl A. Reese, Matthew A. Nolan

Faculty Publications

The effects of meltwater percolation on pollen in snow, firn and glacial ice are not fully understood and currently hamper the use of pollen in ice-core studies of paleoclimate. Several studies have suggested that, due to grain size, pollen is not mobilized by meltwater transport. However, these findings contradict many ice-core pollen studies that show pollen concentrations in snow and firn are much higher than concentrations found in the ice layers they eventually form. This study addresses one aspect of this question by investigating whether meltwater percolation can effectively transport pollen within a snowpack. We used nine Styrofoam coolers filled …

Changes In Substrate Availability Drive Carbon Cycle Response To Chronic Warming, Grace Pold, A. Stuart Grandy, Jerry M. Melillo, Kristen M. Deangelis

Faculty Publications

As earth's climate continues to warm, it is important to understand how the capacity of terrestrial ecosystems to retain carbon (C) will be affected. We combined measurements of microbial activity with the concentration, quality, and physical accessibility of soil carbon to microorganisms to evaluate the mechanisms by which more than two decades of experimental warming has altered the carbon cycle in a Northeast US temperate deciduous forest. We found that concentrations of soil organic matter were reduced in both the organic and mineral soil horizons. The molecular composition of the carbon was altered in the mineral soil with significant reductions …

Modeled Co2 Emissions From Coastal Wetland Transitions To Other Land Uses: Tidal Marshes, Mangrove Forests, And Seagrass Beds, Catherine E. Lovelock, James W. Fourqurean, James T. Morris

Faculty Publications

The sediments of coastal wetlands contain large stores of carbon which are vulnerable to oxidation once disturbed, resulting in high levels of CO2 emissions that may be avoided if coastal ecosystems are conserved or restored. We used a simple model to estimate CO2 emissions from mangrove forests, seagrass beds, and tidal marshes based on known decomposition rates for organic matter in these ecosystems under either oxic or anoxic conditions combined with assumptions of the proportion of sediment carbon being deposited in either oxic or anoxic environments following a disturbance of the habitat. Our model found that over 40 years after …

Oysters And Mammoths: Fossils In Central Texas–Texas Academy Of Science 2017, Chris Barker, R. Larell Nielson

Faculty Publications

Texas Academy of Science, 2017 Field Trip

This year's Texas Academy of Science Geology Field Trip takes you to two very different fossil sites in central Texas. Stop 1 is along a quiet road in the Hill Country where you can collect abundant invertebrate fossils from the Lower Cretaceous Comanche Peak Limestone and Walnut Clay. The second stop of the trip is at one of the newest units of America's park service: the Waco Mammoth National Monument. At this site you will see a spectacular fossil discovery that is now one of the main mammoth sites in North America. And …

Mineralizing Filamentous Bacteria From The Prony Bay Hydrothermal Field Give New Insights Into The Functioning Of Serpentinization-Based Subseafloor Ecosystems, Céline Pisapia, Emmanuelle Gérard, Martine Gérard, Léna Lecourt, Susan Q. Lang, Bernard Pelletier, Claude E. Payri, Christophe Monnin, Linda Guentas, Anne Postec, Marianne Quéméneur, Gaël Erauso, Bénédicte Ménez

Faculty Publications

Despite their potential importance as analogs of primitive microbial metabolisms, the knowledge of the structure and functioning of the deep ecosystems associated with serpentinizing environments is hampered by the lack of accessibility to relevant systems. These hyperalkaline environments are depleted in dissolved inorganic carbon (DIC), making the carbon sources and assimilation pathways in the associated ecosystems highly enigmatic. The Prony Bay Hydrothermal Field (PHF) is an active serpentinization site where, similar to Lost City (Mid-Atlantic Ridge), high-pH fluids rich in H2 and CH4 are discharged from carbonate chimneys at the seafloor, but in a shallower lagoonal environment. This study aimed …

Cover Crop Root Contributions To Soil Carbon In A No-Till Corn Bioenergy Cropping System, Emily E. Austin, Kyle Wickings, Marshall D. Mcdaniel, G. Philip Robertson, A. Stuart Grandy

Faculty Publications

Crop residues are potential biofuel feedstocks, but residue removal may reduce soil carbon (C). The inclusion of a cover crop in a corn bioenergy system could provide additional biomass, mitigating the negative effects of residue removal by adding to stable soil C pools. In a no-till continuous corn bioenergy system in the northern US Corn Belt, we used 13CO2 pulse labeling to trace plant C from a winter rye (Secale cereale) cover crop into different soil C pools for 2 years following rye cover crop termination. Corn stover left as residue (30% of total stover) contributed 66, corn roots 57, …

Metagenomic Identification Of Active Methanogens And Methanotrophs In Serpentinite Springs Of The Voltri Massif, Italy, William J. Brazelton, Christopher N. Thornton, Alex Hyer, Katrina I. Twing, August A. Longino, Susan Q. Lang, Marvin D. Lilley, Gretchen L. Früh-Green, Matthew O. Schrenk

Faculty Publications

The production of hydrogen and methane by geochemical reactions associated with the serpentinization of ultramafic rocks can potentially support subsurface microbial ecosystems independent of the photosynthetic biosphere. Methanogenic and methanotrophic microorganisms are abundant in marine hydrothermal systems heavily influenced by serpentinization, but evidence for methane-cycling archaea and bacteria in continental serpentinite springs has been limited. This report provides metagenomic and experimental evidence for active methanogenesis and methanotrophy by microbial communities in serpentinite springs of the Voltri Massif, Italy. Methanogens belonging to family Methanobacteriaceae and methanotrophic bacteria belonging to family Methylococcaceae were heavily enriched in three ultrabasic springs (pH 12). Metagenomic …

Applying Population And Community Ecology Theory To Advance Understanding Of Belowground Biogeochemistry, Robert W. Buchkowski, Mark A. Bradford, A. Stuart Grandy, Oswald J. Schmitz, William R. Wieder

Faculty Publications

Approaches to quantifying and predicting soil biogeochemical cycles mostly consider microbial biomass and community composition as products of the abiotic environment. Current numerical approaches then primarily emphasise the importance of microbe–environment interactions and physiology as controls on biogeochemical cycles. Decidedly less attention has been paid to understanding control exerted by community dynamics and biotic interactions. Yet a rich literature of theoretical and empirical contributions highlights the importance of considering how variation in microbial population ecology, especially biotic interactions, is related to variation in key biogeochemical processes like soil carbon formation. We demonstrate how a population and community ecology perspective can …

Reconciling Opposing Soil Processes In Row-Crop Agroecosystems Via Soil Functional Zone Management, Alwyn Williams, Adam S. Davis, Andrea Jilling, A. Stuart Grandy, Roger T. Koide, David A. Mortensen, Richard G. Smith, Sieglinde S. Snapp, Kurt A. Spokas, Anthony C. Yannarell, Nicholas R. Jordan

Faculty Publications

Sustaining soil productivity in agricultural systems presents a fundamental agroecological challenge: nutrient provisioning depends upon aggregate turnover and microbial decomposition of organic matter (SOM); yet to prevent soil depletion these processes must be balanced by those that restore nutrients and SOM (soil building processes). These nutrient provisioning and soil building processes are inherently in conflict; management practices that create spatial separation between them may enable each to occur effectively within a single growing season, thereby supporting high crop yield while avoiding soil depletion. Soil functional zone management (SFZM), an understudied but increasingly adopted strategy for annual row-crop production, may help …

Evaporite Karst Geohazards In The Delaware Basin, Texas: Review Of Traditional Karst Studies Coupled With Geophysical And Remote Sensing Characterization, Kevin W. Stafford, Wesley A. Brown, Jon T. Ehrhart, Adam F. Majzoub, Jonathan D. Woodard

Faculty Publications

Evaporite karst throughout the Gypsum Plain of west Texas is complex and extensive, including manifestations ranging from intrastratal brecciation and hypogene caves to epigene features and suffosion caves. Recent advances in hydrocarbon exploration and extraction has resulted in increased infrastructure development and utilization in the area; as a result, delineation and characterization of potential karst geohazards throughout the region have become a greater concern. While traditional karst surveys are essential for delineating the subsurface extent and morphology of individual caves for speleogenetic interpretation, these methods tend to underestimate the total extent of karst development and require surficial manifestation of karst …

Direct Evidence For Microbial-Derived Soil Organic Matter Formation And Its Ecophysiological Controls, Cynthia M. Kallenbach, Serita D. Frey, A. Stuart Grandy

Faculty Publications

Soil organic matter (SOM) and the carbon and nutrients therein drive fundamental submicron- to global-scale biogeochemical processes and influence carbon-climate feedbacks. Consensus is emerging that microbial materials are an important constituent of stable SOM, and new conceptual and quantitative SOM models are rapidly incorporating this view. However, direct evidence demonstrating that microbial residues account for the chemistry, stability and abundance of SOM is still lacking. Further, emerging models emphasize the stabilization of microbial-derived SOM by abiotic mechanisms, while the effects of microbial physiology on microbial residue production remain unclear. Here we provide the first direct evidence that soil microbes produce …

Long-Term Warming Alters Carbohydrate Degradation Potential In Temperate Forest Soils, Grace Pold, Andrew F. Billings, Jeff L. Blanchard, Daniel B. Burkhardt, Serita D. Frey, Jerry M. Melillo, Julia Schnabel, Linda T. A. Van Diepen, Kristen M. Deangelis

Faculty Publications

As Earth's climate warms, soil carbon pools and the microbial communities that process them may change, altering the way in which carbon is recycled in soil. In this study, we used a combination of metagenomics and bacterial cultivation to evaluate the hypothesis that experimentally raising soil temperatures by 5°C for 5, 8, or 20 years increased the potential for temperate forest soil microbial communities to degrade carbohydrates. Warming decreased the proportion of carbohydrate-degrading genes in the organic horizon derived from eukaryotes and increased the fraction of genes in the mineral soil associated with Actinobacteria in all studies. Genes associated with …

Record Of Massive Upwellings From The Pacific Large Low Shear Velocity Province, Pilar Madrigal, Esteban Gazel, Kennet E. Flores, Michael Bizimis, Brian Jicha

Faculty Publications

Large igneous provinces, as the surface expression of deep mantle processes, play a key role in the evolution of the planet. Here we analyse the geochemical record and timing of the Pacific Ocean Large Igneous Provinces and preserved accreted terranes to reconstruct the history of pulses of mantle plume upwellings and their relation with a deep-rooted source like the Pacific large low-shear velocity Province during the Mid-Jurassic to Upper Cretaceous. Petrological modelling and geochemical data suggest the need of interaction between these deep-rooted upwellings and mid-ocean ridges in pulses separated by ∼10–20 Ma, to generate the massive volumes of melt …

Soil Microbial Biomass And Function Are Altered By 12 Years Of Crop Rotation, Marshall D. Mcdaniel, A. Stuart Grandy

Faculty Publications

Declines in plant diversity will likely reduce soil microbial biomass, alter microbial functions, and threaten the provisioning of soil ecosystem services. We examined whether increasing temporal plant biodiversity in agroecosystems (by rotating crops) can partially reverse these trends and enhance soil microbial biomass and function. We quantified seasonal patterns in soil microbial biomass, respiration rates, extracellular enzyme activity, and catabolic potential three times over one growing season in a 12-year crop rotation study at the W. K. Kellogg Biological Station LTER. Rotation treatments varied from one to five crops in a 3-year rotation cycle, but all soils were sampled under …

Sources, Distributions, And Dynamics Of Dissolved Organic Matter In The Canada And Makarov Basins, Yuan Shen, Ronald Benner, Lisa Robbins, Jonathan Wynn

Faculty Publications

A comprehensive survey of dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) was conducted in the Canada and Makarov Basins and adjacent seas during 2010–2012 to investigate the dynamics of dissolved organic matter (DOM) in the Arctic Ocean. Sources and distributions of DOM in polar surface waters were very heterogeneous and closely linked to hydrological conditions. Canada Basin surface waters had relatively low DOC concentrations (69 ± 6 μmol L−1), CDOM absorption (a325: 0.32 ± 0.07 m−1) and CDOM-derived lignin phenols (3 ± 0.4 nmol L−1), and high spectral slope values (S275–295: 31.7 ± …

Comparison Of Permanganate-Oxidizable Carbon And Mineralizable Carbon For Assessment Of Organic Matter Stabilization And Mineralization, Tunsisa T. Hurisso, Steve W. Culman, William R. Horwath, Jordon Wade, Deandra Cass, Joshua W. Beniston, Timothy M. Bowles, A. Stuart Grandy, Alan J. Franzluebbers, Meagan E. Schipanski, Shawn T. Lucas, Carmen M. Ugarte

Faculty Publications

Permanganate-oxidizable C (POXC) and mineralizable C (as determined by short-term aerobic incubation of rewetted soil) are measures of active organic matter that may provide early indication of soil C stabilization and mineralization processes. To date, the relationship between these two promising active organic matter tests has not been comprehensively evaluated, and little is known about their functional role in the soil ecosystem. Here, we examined the relationship between POXC and mineralizable C across a wide range of soil types, management histories, and geographic locations across the United States (13 studies, 76 total sites; n = 1071) and the ability of …

Slowed Biogeochemical Cycling In Sub-Arctic Birch Forest Linked To Reduced Mycorrhizal Growth And Community Change After A Defoliation Event, Thomas C. Parker, Jesse J. Sadowsky, Haley Dunleavy, Jens-Arne Subke, Serita D. Frey, Philip A. Wookey

Faculty Publications

Sub-arctic birch forests (Betula pubescens Ehrh. ssp. czerepanovii) periodically suffer large-scale defoliation events caused by the caterpillars of the geometrid moths Epirrita autumnata and Operophtera brumata. Despite their obvious influence on ecosystem primary productivity, little is known about how the associated reduction in belowground C allocation affects soil processes. We quantified the soil response following a natural defoliation event in sub-arctic Sweden by measuring soil respiration, nitrogen availability and ectomycorrhizal fungi (EMF) hyphal production and root tip community composition. There was a reduction in soil respiration and an accumulation of soil inorganic N in defoliated plots, symptomatic of a slowdown …

Calcification Of The Planktonic Foraminiferaglobigerinabulloidesand Carbonate Ion Concentration Resultsfrom The Santa Barbara Basin, Emily B. Osborne, Robert C. Thunell, Brittney J. Marshall, Jessica A. Holm, Eric J. Tappa, Claudia R. Benitez-Nelson, Wei‐Jun Cai, Baoshan Chen

Faculty Publications

Planktonic foraminiferal calcification intensity, reflected by shell wall thickness, has been hypothesized to covary with the carbonate chemistry of seawater. Here we use both sediment trap and box core samples from the Santa Barbara Basin to evaluate the relationship between the calcification intensity of the planktonic foraminifera species Globigerina bulloides, measured by area density (µg/µm2), and the carbonate ion concentration of seawater ([CO32−]). We also evaluate the influence of both temperature and nutrient concentration ([PO43−]) on foraminiferal calcification and growth. The presence of two G. bulloides morphospecies with systematically different calcification properties and offset stable isotopic compositions was identified within …

Eleven Years Of Crop Diversification Alters Decomposition Dynamics Of Litter Mixtures Incubated With Soil, M. D. Mcdaniel, A. Stuart Grandy, Lisa K. Tiemann, Michael N. Weintraub

Faculty Publications

Agricultural crop rotations have been shown to increase soil carbon (C), nitrogen (N), and microbial biomass. The mechanisms behind these increases remain unclear, but may be linked to the diversity of crop residue inputs to soil organic matter (SOM). We used a residue mixture incubation to examine how variation in long-term diversity of plant communities in agroecosystems influences decomposition of residue mixtures, thus providing a comparison of the effects of plant diversification on decomposition in the long term (via crop rotation) and short term (via residue mixtures). Three crop residue mixtures, ranging in diversity from two to four species, were …

Precision Control Of Soil Nitrogen Cycling Via Soil Functional Zone Management, Alwyn Williams, Adam S. Davis, Patrick M. Ewing, A. Stuart Grandy, Daniel A. Kane, Roger T. A. Koide, David A. Mortensen, Richard G. Smith, Sieglinde S. Snapp, Kurt A. Spokas, Anthony C. Yannarell, Nicholas R. Jordan

Faculty Publications

Managing the soil nitrogen (N) cycle is a major component of agricultural sustainability. Soil functional zone management (zonal management) is a novel agroecological strategy for managing row-crop agroecosystems. It may improve the efficiency of soil N cycling compared with conventional and no-tillage approaches, by managing the timing and location (crop row vs inter-row) of key soil N cycling processes. We compared N mineralization and availability during the period of maize peak N demand in crop rows and inter-rows in zonal management and conventional chisel plow tillage systems at four sites across the US Corn Belt over three growing seasons. Under …