Biogeochemistry Commons^™

Rapid Bacterial And Fungal Successional Dynamics In First Year After Chaparral Wildfire, M. Fabiola Pulido-Chavez, James W. J. Randolph, Cassandra A. Zalman, Loralee Larios, Peter M. Homyak, Sydney I. Glassman

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

The rise in wildfire frequency and severity across the globe has increased interest in secondary succession. However, despite the role of soil microbial communities in controlling biogeochemical cycling and their role in the regeneration of post-fire vegetation, the lack of measurements immediately post-fire and at high temporal resolution has limited understanding of microbial secondary succession. To fill this knowledge gap, we sampled soils at 17, 25, 34, 67, 95, 131, 187, 286, and 376 days after a southern California wildfire in fire-adapted chaparral shrublands. We assessed bacterial and fungal biomass with qPCR of 16S and 18S and richness and composition …

Diversifying And Perennializing Plants In Agroecosystems Alters Retention Of New C And N From Crop Residues, Marshall D. Mcdaniel, Jeffrey A. Bird, Jennifer Pett-Ridge, Erika Marin-Spiotta, Tom M. Schmidt, A. Stuart Grandy

Faculty Publications

Managing soils to retain new plant inputs is key to moving toward a sustainable and regenerative agriculture. Management practices, like diversifying and perennializing agroecosystems, may affect the decomposer organisms that regulate how new residue is converted to persistent soil organic matter. Here we tested whether 12 years of diversifying/perennializing plants in agroecosystems through extended rotations or grassland restoration would decrease losses of new plant residue inputs and, thus, increase retention of carbon (C) and nitrogen (N) in soil. We tracked dual-labeled (13C and 15N), isotopically enriched wheat (Triticum aestivum) residue in situ for 2 years as it decomposed in three …

Larval Ecology Of Atlantic Bluefin Tuna (Thunnus Thynnus): New Insights From Otolith Microstructure, Biotic, And Abiotic Analyses From The Gulf Of Mexico And Mediterranean Sea, Estrella Malca

All HCAS Student Capstones, Theses, and Dissertations

Atlantic bluefin tuna (ABT), Thunnus thynnus, spawn in the Gulf of Mexico (GoM) and the Mediterranean Sea (MED). Spawning occurs within narrow temporal and environmental parameters. Efforts to characterize growth of ABT in wild conditions revealed a wide range of growth variability during the early life stages. This series of studies examined potential biotic and abiotic influences of larval growth from seven ABT cohorts, and identified several key drivers of growth for this commercially valuable species. A detailed investigation of larval dynamics using otolith microstructure was conducted as follows. First, companion growth curves and stable isotope analysis from the same …

Us Scientific Leadership Addressing Energy, Ecosystems, Climate, And Sustainable Prosperity: Report In Brief From The Berac Subcommittee On International Benchmarking, Maureen Mccann, Patrick Reed, Ana Alonso, Ludmilla Aristilde, Massie S. Ballon, Crysten Blaby, Allison A. Campbell, Kenneth James Davis, Brian H. Davison, Ben Evans, Robert F. Fischetti, Serita D. Frey, Ann M. Fridlind, Efi Foufoula-Georgiou, Ramon Gonzalez, Michael N. Gooseff, Nathan Hillson, Janet Jansson, Klaus Keller, Markus Kleber, Costas Maranas, Gerald A. Meehl, Himadri Pakrasi, Jennifer Pett-Ridge, Kristala Prather, Johannes Quaas, G. Philip Robertson, Alistair Rogers, Tim Scheibe, Thomas R. Schneider, Gary Stacey, Margaret S. Torn, Kerstin Kleese Van Dam, Detlef Vuuren, John Weyant, Stan Wullschleger, Shaocheng Xie, Seung Yon (Sue) Rhee, Huimin Zhao

Faculty Publications

This document presents the subcommittee’s overarching and domain-specific findings and recommendations for the next decade, identified by consensus across the full BERAC subcommittee and experts interviewed for this assessment.

The Binding Of The Micronutrient Transition Metals To The Alkylation Products Of Chemical Warfare Agent, Sulfur Mustard, And Thiols, Potentially Giving New Understanding To Physiological Effects Of Exposure And Increased Toxicity, Colin O'Donnell

Graduate Theses and Dissertations

Model compounds, 3,6,9-trithaiundecane-1,11-dicarboxylic acid (TTDPA), 2,5,8-trithianonane-1,9-dicarboxylic acid (TTDAA), and 1,11-diamide-3,6,9-trithiaundecane (TTDAce), closely related to the adducts formed by cysteine alkylation of the chemical weapon, sulfur mustard, were synthesized. It is shown that TTDPA forms complexes with key metal micronutrients: copper, nickel, cobalt, manganese, and zinc. Though the strength of binding to TTDPA varies, the complexes in many cases precipitate from solution. All metals produced a visible precipitate upon interaction with TTDPA under the conditions tested, however only Cu2+, Mn2+, and Zn2+ produced enough to be measured. The mass of formed precipitate seemed to peak at an equimolar ratio of TTDPA …

Substrate Availability And Not Thermal Acclimation Controls Microbial Temperature Sensitivity Response To Long-Term Warming, Luiz A. Domeignoz-Horta, Grace Pold, Hailey Erb, David Sebag, Eric Verrecchia, Trent Northen, Katherine Louie, Emiley Eloe-Fadrosh, Christa Pennacchio, Melissa A. Knorr, Serita D. Frey, Jerry M. Melillo, Kristen M. Deangelis

Faculty Publications

Microbes are responsible for cycling carbon (C) through soils, and predicted changes in soil C stocks under climate change are highly sensitive to shifts in the mechanisms assumed to control the microbial physiological response to warming. Two mechanisms have been suggested to explain the long-term warming impact on microbial physiology: microbial thermal acclimation and changes in the quantity and quality of substrates available for microbial metabolism. Yet studies disentangling these two mechanisms are lacking. To resolve the drivers of changes in microbial physiology in response to long-term warming, we sampled soils from 13- and 28-year-old soil warming experiments in different …

Soil Microbial Communities Vary In Composition And Functional Strategy Across Soil Aggregate Size Class Regardless Of Tillage, Lukas T. Bernhardt, Richard G. Smith, Andrew S. Grandy, Jessica E. Mackay, Nicholas D. Warren, Kevin M. Geyer, Jessica G. Ernakovich

Faculty Publications

The physicochemical environment within aggregates controls the distribution of carbon and microbial communities in soils. Agricultural management, such as tillage, can disrupt aggregates and the microscale habitat provided to microorganisms, thus altering microbial community dynamics. Categorizing microbial communities into life history strategies with shared functional traits—as has been done to understand plant community structure for decades—can illuminate how the soil physicochemical environment constrains the membership and activity of microbial communities. We conducted an aggregate scale survey of microbial community composition and function through the lens of the yield–acquisition–stress (Y–A–S) tolerator life history framework. Soils collected from a 7-year tillage experiment …

The Nitrogen Dynamics Of Deer Cave, Sarawak, And The Role Of Bat Caves As Biogeochemical Sinks In Tropical Moist Forests., Joyce Lundberg, Donald A. Mcfarlane, Guy Van Rentergem

International Journal of Speleology

A better understanding of the role of bat caves as nitrogen sinks in tropical moist forest ecosystems can be expected to shed light on regional and spatial variability in nutrient recycling studies. We measured the nitrogen flux (in air and water) associated with a very large Chaerephon plicata bat colony in Deer Cave, Borneo, in the process generating a new, quantitative, estimate of the total bat population (774,828 ±48,320), and the first detailed modelling of an ammonia plume in a cave. Long-term storage of N does not occur in this wet cave. Our final budget numbers indicate that, of the …

Environmental Controls On Carbon Biogeochemistry In Aquatic Systems, Lee Potter

LSU Master's Theses

Carbon dioxide (CO₂) outgassing from inland waters is a small but critical component of the global carbon cycle that is currently not well constrained. This thesis is composed of three interrelated studies with an overarching goal to further determine environmental factors impacting carbon dynamics in rivers and lakes. These studies utilized water samples and in situ measurements of pCO₂ and ambient water parameters from the Lower Mississippi River at Baton Rouge and University Lake in Baton Rouge Louisiana, USA collected between January 2021 and August 2022. Additional Meteorological and hydrological data were download from public sources. Results …

Concentration Of Heavy Metals In Three Distinct Algae Families From Humboldt County, California, Kodiak E. Miller, Caleb J. Strait, Jacob I. Begorre, Brittney L. Mitchell, Claire P. Till

IdeaFest: Interdisciplinary Journal of Creative Works and Research from Cal Poly Humboldt

Anthropogenic impacts on marine environments can impact metal fluxes and concentrations available to marine species. Monitoring these impacts is necessary to better understand the interactions between the biotic and abiotic components of these ecosystems and mitigate the risk posed by harmful toxins introduced by human activities. Biomoniters, like macroscopic algae, are useful indicators that illuminate the bioaccumulation of toxins commonly introduced from anthropogenic activity. With this in mind, the concentrations of heavy metals zinc (Zn), nickel (Ni), and copper (Cu) were analyzed via the assessment of algae (Representatives from Ulva, Mastocarpus, Fucus) in two sites in Humboldt County: …

Evaluating The Impact Of Submarine Groundwater Discharge On Nutrients And Trace Elements In Coastal Systems: The Examples Of The Tuckean Swamp (Australia) And The Mississippi Sound (Usa), Amy Moody

Dissertations

Submarine groundwater discharge (SGD) is the advective flow of both fresh terrestrial groundwater and recirculating seawater through aquifer sediments, which is released into the coastal ocean. In this dissertation, I evaluated the impact of SGD on the distributions and input of trace metals and nutrients. In the Tuckean Swamp, an estuary in Australia dominated by coastal acid sulfate soils, I determined the impact of groundwater on Ba and U during the flood season, when the local aquifer is flushed out after a rapid increase in water table elevation. For Ba and U, groundwater contributed up to 18 and 66 % …

Permafrost And Climate Change: Carbon Cycle Feedbacks From The Warming Arctic, Edward A. G. Schuur, Benjamin W. Abbott, Roisin Commane, Jessica G. Ernakovich, Eugenie Euskirchen, Gustaf Hugelius, Guido Grosse, Miriam Jones, Charlie Koven, Victor Leshyk, David Lawrence, Michael M. Loranty, Marguerite Mauritz, David Olefeldt, Susan Natali, Heidi Rodenhizer, Verity Salmon, Christina Schadel, Jens Strauss, Claire C. Treat, Merritt Turetsky

Faculty Publications

Rapid Arctic environmental change affects the entire Earth system as thawing permafrost ecosystems release greenhouse gases to the atmosphere. Understanding how much permafrost carbon will be released, over what time frame, and what the relative emissions of carbon dioxide and methane will be is key for understanding the impact on global climate. In addition, the response of vegetation in a warming climate has the potential to offset at least some of the accelerating feedback to the climate from permafrost carbon. Temperature, organic carbon, and ground ice are key regulators for determining the impact of permafrost ecosystems on the global carbon …

Nutrient Dynamics And Ecosystem Development Of Urban Forests, Gisselle A. Mejía

Dissertations, Theses, and Capstone Projects

Urban growth and expansion are a major component of global environmental change, with impacts on climate, air and water quality, biodiversity, and human well-being. Forests embedded in urban landscapes are critical in mitigating these impacts at local, regional, and continental scales. However, assessing urban forests is difficult because cities are heterogenous in physical, chemical, biological, and social dimensions. This heterogeneity has constrained how urban forests are defined, and therefore, how they are studied. The objective of this dissertation is to determine how these biophysical and social factors drive ecological processes in urban forests and will address three outstanding challenges in …

The Interaction Of Different Primary Producers And Physical And Chemical Dynamics Of An Urban Shallow Lake, Majid Sahin

Dissertations, Theses, and Capstone Projects

An artificial urban shallow lake, Prospect Park Lake (PPL), is situated on a terminal moraine in Brooklyn New York, and supplied with municipal water treated with ortho-phosphates. The constant input of the phosphate nutrient is the primary source of eutrophication in the lake. The numerous pools along the water course houses various aquatic phototrophs, which influence the water quality and the state of the system, driving conditions into favoring the survival of their species. In the first half of the dissertation, the focus of the project is on analyzing how the different primary producers in different regions of PPL affect …

Determining The Effects Of Elevated Carbon Dioxide On Soil Acidification, Cation Depletion, And Soil Inorganic Carbon And Mapping Soil Carbons Using Artificial Intelligence, Jannatul Ferdush

Theses and Dissertations

Soil carbon is the largest sink and source of the global carbon cycle and is disturbed by several natural, anthropogenic, and environmental factors. The global increase of atmospheric CO₂ affects soil carbon cycling through varied biogeochemical processes. The first chapter is a compilation of current information on potential factors triggering soil acidification and weathering mechanisms under elevated CO₂ and their consequences on soil inorganic carbon (SIC) pool and quality. Soil water content and precipitation were critical factors influencing elevated CO₂ effects on the SIC pool. The second chapter examines a detailed column experiment in which six soils …

Microtopography Matters: Belowground Ch4 Cycling Regulated By Differing Microbial Processes In Peatland Hummocks And Lawns, Clarice R. Perryman, Carmody K. Mccalley, Jessica G. Ernakovich, Louis J. Lamit, Joanne H. Shorter, Erik Lilleskov, Ruth K. Varner

Faculty Publications

Water table depth and vegetation are key controls of methane (CH4) emissions from peatlands. Microtopography integrates these factors into features called microforms. Microforms often differ in CH4 emissions, but microform-dependent patterns of belowground CH4 cycling remain less clearly resolved. To investigate the impact of microtopography on belowground CH4 cycling, we characterized depth profiles of the community composition and activity of CH4-cycling microbes using 16S rRNA amplicon sequencing, incubations, and measurements of porewater CH4 concentration and isotopic composition from hummocks and lawns at Sallie's Fen in NH, USA. Geochemical proxies of methanogenesis and methanotrophy indicated that microforms differ in dominant microbial …

The Paleoecology Of High-Elevation Bison In The Greater Yellowstone Ecosystem And Implications For Modern Bison Conservation, Darian Bouvier

Electronic Theses and Dissertations

The national mammal of the United States, the American Bison (Bison bison) was once nearly extinct. Populations have recovered to the degree that thousands roam the Great Plains today. Due to their large numbers and body size, this species has an oversized impact on the ecological communities where it lives and is considered a keystone herbivore in modern North American grasslands. This study explores the detailed, seasonally resolved, paleoecology of seven bison from the Greater Yellowstone Ecosystem during the Late Holocene through stable isotope analyses and species niche modeling. Isotopic analyses of δ¹³C, δ¹⁵N, …

Wetland Soil Development Along Salinity And Hydrogeomorphic Gradients In Active And Inactive Deltaic Basins Of Coastal Louisiana, Amanda Fontenot

LSU Master's Theses

Coastal wetlands provide an abundance of ecosystem services that benefit society, such as essential habitat for commercial species, storm protection, nutrient cycling, and carbon storage. Louisiana faces rapid rates of relative sea level rise (natural subsidence and eustatic sea levels) that threaten wetland survival, which are amplified by a reduction of riverine sediment input. An important determining factor of marsh survival is the formation of wetland platform elevation, known as vertical accretion, which is determined by several processes including sediment deposition & erosion, below ground biomass (BGB) productivity, decomposition of organic matter, shallow & deep subsidence, and soil compaction. Feldspar …

We Must Stop Fossil Fuel Emissions To Protect Permafrost Ecosystems, Benjamin W. Abbott, Michael Brown, Joanna C. Carey, Jessica G. Ernakovich, Jennifer M. Frederick, Laodong Guo, Gustaf Hugelius, Raymond M. Lee, Michael M. Loranty, Robie Macdonald, Paul J. Mann, Susan M. Natali, David Olefeldt, Pam Pearson, Abigail Rec, Martin Robards, Verity G. Salmon, Sara Sayedi, Christina Schadel, Edward A. G. Schuur, Sarah Shakil, Arial J. Shogren, Jens Strauss, Suzanne E. Tank, Brett F. Thornton, Rachael Treharne, Merritt Turetsky, Carolina Voigt, Nancy Wright, Yuanhe Yang, Jay P. Zarnetske, Qiwen Zhang, Scott Zolkos

Faculty Publications

Climate change is an existential threat to the vast global permafrost domain. The diverse human cultures, ecological communities, and biogeochemical cycles of this tenth of the planet depend on the persistence of frozen conditions. The complexity, immensity, and remoteness of permafrost ecosystems make it difficult to grasp how quickly things are changing and what can be done about it. Here, we summarize terrestrial and marine changes in the permafrost domain with an eye toward global policy. While many questions remain, we know that continued fossil fuel burning is incompatible with the continued existence of the permafrost domain as we know …

Microbiome Assembly In Thawing Permafrost And Its Feedbacks To Climate, Jessica G. Ernakovich, Robyn A. Barbato, Virginia I. Ritch, Christina Schadel, Rebecca E. Hewitt, Stacey J. Doherty, Emily D. Whalen, Benjamin Abbott, Jiri Barta, Christina Biasi, Chris L. Chabot, Jenni Hultman, Christian Knoblauch, Maggie C. Y. Lau Vetter, Mary-Cathrine Leewis, Susanne Liebner, Rachel Mackelprang, Tullis C. Onstott, Andreas Richter, Ursel M. E. Schutte, Henri M. P. Siljanen, Neslihan Tas, Ina Timling, Tatiana A. Vishnivetskaya, Mark P. Waldrop, Matthias Winkel

Faculty Publications

The physical and chemical changes that accompany permafrost thaw directly influence the microbial communities that mediate the decomposition of formerly frozen organic matter, leading to uncertainty in permafrost–climate feedbacks. Although changes to microbial metabolism and community structure are documented following thaw, the generality of post-thaw assembly patterns across permafrost soils of the world remains uncertain, limiting our ability to predict biogeochemistry and microbial community responses to climate change. Based on our review of the Arctic microbiome, permafrost microbiology, and community ecology, we propose that Assembly Theory provides a framework to better understand thaw-mediated microbiome changes and the implications for community …

Petrographic And Geochemical Records Of Climate Perturbation In Carbonates From A Perennially Ice-Covered Antarctic Lake, Jared Clance

Earth and Planetary Sciences ETDs

Carbonate precipitation in perennially ice-covered Lake Fryxell, McMurdo Dry Valleys, Antarctica produces a modern analog for Antarctic paleolake carbonates. Lake Fryxell contains a steep oxycline in the photic zone, where dissolved oxygen falls from supersaturation to zero. In the lake’s benthic microbial mats, oxygen concentrations are higher than in the water column due to microbial photosynthesis. These mats contain carbonate cements that precipitated in a discrete episode from mat pore waters. Precipitation continued through seasonal fluctuations in oxygenation, demonstrated by variable concentrations of oxidized and reduced manganese and iron within carbonates. Carbonates precipitated out of isotopic equilibrium with the lake …

Understanding Biogeochemical And Physical Controls On Methane Air-Sea Exchange Fluxes In The Pacific Ocean, Sarah Raney

Master's Theses

Methane and trace element samples were collected on GEOTRACES GP15 Pacific Meridional Transect (PMT) cruise conducted between the Aleutian Islands (57 °N) and Tahiti (20 °S) from September to November 2018. Uncertainty in methane air-sea exchange fluxes was determined using a propagation of errors approach. Fluxes ranged from -0.88 to 4.9 µmol CH₄ m^-2 d^-1. Average CH₄ flux along the Alaskan margin was 2.2 ± 2.9 µmol CH₄ m^-2 d^-1. Methane fluxes decreased moving southward and increased to their open ocean maximum around 20 °N before declining in equatorial waters. Near …

Water Quality Assessment Of Karst Spring Water As A Private Water Supply Source In Northeast Tennessee, Lukman Fashina

Electronic Theses and Dissertations

Karst springs are an essential source of private water supply for about 10% of households in Tennessee. However, these springs, which can be easily polluted, are unregulated. This study, therefore, assesses water quality spatial patterns and water quality rating of roadside springs in northeast Tennessee.

Karst spring water samples collected from 50 springs were assessed using EPA Standard methods for pathogens, nutrients, radon, and physicochemical parameters. Springs generally met federal and state standards for physicochemical parameters, 90% of samples contained E. coli, and all samples contained fecal coliform. High E. coli was spatially clustered causing a fecal contamination hot …

Soil Volatile Organic Compound Emissions In Response To Soil Warming And Nitrogen Deposition, A. L. Romero-Olivares, C. L. Davie-Martin, M. Kramshoj, R. Rinnan, Serita D. Frey

Faculty Publications

Biogenic volatile organic compounds (VOCs) play crucial roles in ecosystems at multiple scales, ranging from mediating soil microbial interactions to contributing to atmospheric chemistry. However, soil VOCs and how they respond to environmental change remains understudied. We aimed to assess how 2 abiotic global change drivers, soil warming and simulated nitrogen (N) deposition, impact soil VOC emissions over time in a temperate forest. We characterized the effect of warming, N deposition, and their interaction on the composition and emissions of soil VOCs during the growing season of 2 consecutive years. We found that chronic warming and N deposition enhanced total …

Controls On Buffering And Coastal Acidification In A Temperate Estuary, Christopher W. Hunt, Joseph Salisbury, Douglas Vandemark

Faculty Publications

Estuaries may be uniquely susceptible to the combined acidification pressures of atmospherically driven ocean acidification (OA), biologically driven CO2 inputs from the estuary itself, and terrestrially derived freshwater inputs. This study utilized continuous measurements of total alkalinity (TA) and the partial pressure of carbon dioxide (pCO2) from the mouth of Great Bay, a temperate northeastern U.S. estuary, to examine the potential influences of endmember mixing and biogeochemical transformation upon estuary buffering capacity (β–H). Observations were collected hourly over 28 months representing all seasons between May 2016 and December 2019. Results indicated that endmember mixing explained most of the observed variability …

A Remote Sensing And Machine Learning-Based Approach To Forecast The Onset Of Harmful Algal Bloom (Red Tides), Moein Izadi

Dissertations

In the last few decades, harmful algal blooms (HABs, also known as “red tides”) have become one of the most detrimental natural phenomena all around the world especially in Florida’s coastal areas due to local environmental factors and global warming in a larger scale. Karenia brevis produces toxins that have harmful effects on humans, fisheries, and ecosystems. In this study, I developed and compared the efficiency of state-of-the-art machine learning models (e.g., XGBoost, Random Forest, and Support Vector Machine) in predicting the occurrence of HABs. In the proposed models, the K. brevis abundance is used as the target, and 10 …

Fast-Decaying Plant Litter Enhances Soil Carbon In Temperate Forests But Not Through Microbial Physiological Traits, Matthew E. Craig, Kevin M. Geyer, Katilyn V. Beidler, Edward R. Brzostek, Serita D. Frey, A. Stuart Grandy, Chao Liang, Richard P. Phillips

Faculty Publications

Conceptual and empirical advances in soil biogeochemistry have challenged long-held assumptions about the role of soil micro-organisms in soil organic carbon (SOC) dynamics; yet, rigorous tests of emerging concepts remain sparse. Recent hypotheses suggest that microbial necromass production links plant inputs to SOC accumulation, with high-quality (i.e., rapidly decomposing) plant litter promoting microbial carbon use efficiency, growth, and turnover leading to more mineral stabilization of necromass. We test this hypothesis experimentally and with observations across six eastern US forests, using stable isotopes to measure microbial traits and SOC dynamics. Here we show, in both studies, that microbial growth, efficiency, and …

Initial Soil Conditions Outweigh Management In A Cool-Season Dairy Farm's Carbon Sequestration Potential, Kyle A. Arndt, Eleanor E. Campbell, Chris D. Dorich, A. Stuart Grandy, Timothy S. Griffin, Peter Ingraham, Apryl L. Perry, Ruth K. Varner, Alexandra R. Contosta

Faculty Publications

Pastures and rangelands are a dominant portion of global agricultural land and have the potential to sequester carbon (C) in soils, mitigating climate change. Management intensive grazing (MIG), or high density grazing with rotations through paddocks with long rest periods, has been highlighted as a method of enhancing soil C in pastures by increasing forage production. However, few studies have examined the soil C storage potential of pastures under MIG in the northeastern United States, where the dairy industry comprises a large portion of agricultural use and the regional agricultural economy. Here we present a 12-year study conducted in this …

Microbial Feedbacks On Soil Organic Matter Dynamics Underlying The Legacy Effect Of Diversified Cropping Systems, Maria Mooshammer, A. Stuart Grandy, Francisco Calderon, Steve Culman, Bill Deen, Rhae A. Drijber, Kari Dunfield, Virginia L. Jin, R. Michael Lehman, Shannon L. Osborne, Marty Schmer, Timothy M. Bowles

Faculty Publications

Crop rotations have well-known aboveground and belowground benefits. At regional to continental scales, the unifying mechanisms of how diversified rotations alter soil organic matter (SOM) dynamics have not been demonstrated. We assessed how increasing crop rotational diversity across a soil-climate gradient affected the integrated response of SOM chemistry, microbial community composition, and its enzymatic potential to degrade SOM. Agroecosystems with the same crop rotational diversity (all sampled during the corn phase) shared similarities in molecular SOM patterns with a strong microbial signature, pointing to common transformation processes. Differences in SOM chemistry between rotations were mainly characterized by shifts in microbial …

Dominance Of Diffusive Methane Emissions From Lowland Headwater Streams Promotes Oxidation And Isotopic Enrichment, Andrew L. Robison, Wilfred M. Wollheim, Clarice R. Perryman, Annie R. Cotter, Jessica E. Mackay, Ruth K. Varner, Paige Clarizia, Jessica G. Ernakovich

Faculty Publications

Inland waters are the largest natural source of methane (CH4) to the atmosphere, yet the contribution from small streams to this flux is not clearly defined. To fully understand CH4 emissions from streams and rivers, we must consider the relative importance of CH4 emission pathways, the prominence of microbially-mediated production and oxidation of CH4, and the isotopic signature of emitted CH4. Here, we construct a complete CH4 emission budgets for four lowland headwater streams by quantifying diffusive CH4 emissions and comparing them to previously published rates of ebullitive emissions. We also examine the isotopic composition of CH4 along with the …