Nutrient Addition Effects On Tropical Dry Forests: A Mini-Review From Microbial To Ecosystem Scales,
2015
University of Minnesota, Saint Paul
Nutrient Addition Effects On Tropical Dry Forests: A Mini-Review From Microbial To Ecosystem Scales, Jennifer S. Powers, Kristen K. Becklund, Maria G. Gei, Siddharth B. Iyengar, Rebecca Meyer, Christine S. O'Connell, Erik M. Schilling, Christina M. Smith, Bonnie G. Waring, Leland K. Werden
Biology, Chemistry, and Environmental Sciences Faculty Articles and Research
Humans have more than doubled inputs of reactive nitrogen globally and greatly accelerated the biogeochemical cycles of phosphorus and metals. However, the impacts of increased element mobility on tropical ecosystems remain poorly quantified, particularly for the vast tropical dry forest biome. Tropical dry forests are characterized by marked seasonality, relatively little precipitation, and high heterogeneity in plant functional diversity and soil chemistry. For these reasons, increased nutrient deposition may affect tropical dry forests differently than wet tropical or temperate forests. Here, we review studies that investigated how nutrient availability affects ecosystem and community processes from the microsite to ecosystem scales …
Representing Life In The Earth System With Soil Microbial Functional Traits In The Mimics Model,
2015
National Center for Atmospheric Research
Representing Life In The Earth System With Soil Microbial Functional Traits In The Mimics Model, William R. Wieder, A. Stuart Grandy, Cynthia M. Kallenbach, P. G. Taylor, G. B. Bonan
Faculty Publications
Projecting biogeochemical responses to global environmental change requires multi-scaled perspectives that consider organismal diversity, ecosystem processes, and global fluxes. However, microbes, the drivers of soil organic matter decomposition and stabilization, remain notably absent from models used to project carbon (C) cycle–climate feedbacks. We used a microbial trait-based soil C model with two physiologically distinct microbial communities, and evaluate how this model represents soil C storage and response to perturbations. Drawing from the application of functional traits used to model other ecosystems, we incorporate copiotrophic and oligotrophic microbial functional groups in the MIcrobial-MIneral Carbon Stabilization (MIMICS) model; these functional groups are …
Estimates Of Micro-, Nano-, And Picoplankton Contributions To Particle Export In The Northeast Pacific,
2015
University of Rhode Island
Estimates Of Micro-, Nano-, And Picoplankton Contributions To Particle Export In The Northeast Pacific, B. L. Mackinson, S. B. Moran, M. W. Lomas, Gillian M. Stewart, R. P. Kelly
Publications and Research
The contributions of micro-, nano-, and picoplankton to particle export were estimated from measurements of size-fractionated particulate 234Th, organic carbon, and phytoplankton indicator pigments obtained during five cruises between 2010 and 2012 along Line P in the subarctic northeast Pacific Ocean. Sinking fluxes of particulate organic carbon (POC) and indicator pigments were calculated from 234Th;238U disequilibria and, during two cruises, measured by a sediment trap at Ocean Station Papa. POC fluxes at 100m ranged from 0.65 to 7.95 mmolm2 d1, similar in magnitude to previous results at Line P. Microplankton pigments dominate indicator pigment fluxes (averaging 6919% of total pigment …
Crop Rotational Diversity Enhances Belowground Communities And Functions In An Agroecosystem,
2015
University of New Hampshire, Durham
Crop Rotational Diversity Enhances Belowground Communities And Functions In An Agroecosystem, L. K. Tiemann, A. Stuart Grandy, E. E. Atkinson, E. Marin-Spiotta, M. D. Mcdaniel
Faculty Publications
Biodiversity loss, an important consequence of agricultural intensification, can lead to reductions in agroecosystem functions and services. Increasing crop diversity through rotation may alleviate these negative consequences by restoring positive aboveground–belowground interactions. Positive impacts of aboveground biodiversity on belowground communities and processes have primarily been observed in natural systems. Here, we test for the effects of increased diversity in an agroecosystem, where plant diversity is increased over time through crop rotation. As crop diversity increased from one to five species, distinct soil microbial communities were related to increases in soil aggregation, organic carbon, total nitrogen, microbial activity and decreases in …
Methane Emissions From Direct-Seeded, Delayed-Flood Rice Grown On A Clay Soil,
2015
University of Arkansas, Fayetteville
Methane Emissions From Direct-Seeded, Delayed-Flood Rice Grown On A Clay Soil, Alden Daniel Smartt
Graduate Theses and Dissertations
Due to the production of methane (CH4) under flooded-soil conditions, rice (Oryza sativa L.) cultivation is a major contributor to agricultural CH4 emissions. Studies examining CH4 emissions from rice have only recently been initiated in Arkansas and no data have been collected from rice produced on clay soils in Arkansas. Therefore, research was conducted in 2012 and 2013 at the Northeast Research and Extension Center in Keiser, Arkansas to examine the factors affecting CH4 emissions from rice produced on a Sharkey clay (very-fine, smectitic, thermic Chromic Epiaquerts). The objectives of this study were to determine: 1) the effect of vegetation …
Biogeochemical Cycling In A Headwater Stream And Riparian Zone,
2015
Montana Tech of the University of Montana
Biogeochemical Cycling In A Headwater Stream And Riparian Zone, A. Capri Gillam
Graduate Theses & Non-Theses
Several teams of researchers at multiple universities are currently measuring annual and seasonal fluxes of carbon dioxide and other greenhouses gases (nitrous oxide and methane) in riparian wetlands and upland forests in the Tenderfoot Creek Experimental Forest (TCEF), a subalpine watershed in the Little Belt Mountains, Montana. In the current thesis, the author characterized the geochemistry and stable carbon isotope composition of shallow groundwater, soil water, and stream water in upper Stringer Creek, near sites that are being investigated for gas chemistry and microbial studies. It was hypothesized that if methanogenesis were a dominant process in the riparian wetlands of …
A Survey Of Aquatic Organisms For The Cyanotoxin Beta-Methylamino-L-Alanine (Bmaa),
2015
Old Dominion University
A Survey Of Aquatic Organisms For The Cyanotoxin Beta-Methylamino-L-Alanine (Bmaa), Ian M. Sammler
OES Theses and Dissertations
Cyanobacteria blooms are increasing globally as a result of eutrophication. Many cyanobacteria are potentially harmful, not only because of the oxygen depleted zones created when they decay, but also because of the toxins they produce. β- Methylamino-L-alanine (BMAA), reportedly produced by many species of cyanobacteria, is a non-proteinogenic amino acid that has been linked to the development of neurodegenerative diseases (amyotrophic lateral sclerosis (ALS) and Alzheimer's) in humans. This study presents results from an assessment of BMAA in cyanobacteria and their grazers from the lower Chesapeake Bay and Lake Erie regions. BMAA was analyzed in samples prepared with the EZ:Faast™ …
Sources Of Nutrient And Escherichia Coli Contamination Within The Otter Creek Watershed, Madison County, Kentucky,
2015
Eastern Kentucky University
Sources Of Nutrient And Escherichia Coli Contamination Within The Otter Creek Watershed, Madison County, Kentucky, Nathaniel C. Crockett, Walter S. Borowski
EKU Faculty and Staff Scholarship
The Otter Creek watershed exhibits dissolved nutrient (ammonium, NH4; nitrate, NO3; phosphate, PO4) and Escherichia coli contamination that compromises its water quality. The watershed covers a substantial portion of Madison County and consists of Lake Reba, Dreaming Creek, and east and west forks, all of which enter the trunk of Otter Creek before flowing into the Kentucky River. Suspected contaminate sources include leaky sewage system pipes, runoff from pasture land, and septic system leachate. We collected 330 water samples on three occasions during summer 2014 to determine the extent and sources of contamination. Nutrients …
Stoichiometric Controls On Denitrification In High Nitrate Watersheds,
2015
Illinois State University
Stoichiometric Controls On Denitrification In High Nitrate Watersheds, Brian Grebliunas
Theses and Dissertations
Watershed biogeochemistry throughout Midwestern agroecosystems have been altered through hydrologic manipulation and over-application of nitrogenous fertilizers. As a result, nitrate (NO3-N) export from subsurface drainage has negative impacts on local and downstream ecosystem health. Wetland installation has proven to be a viable option for targeted management where a large proportion of NO3-N is removed through the bacterially mediated process denitrification. For denitrification to maintain high rates under prolonged NO3-N saturation, a stable supply of labile dissolved organic carbon (DOC) is required. The focus of this dissertation was to study how the stoichiometry of agricultural wetlands limits denitrification within a controlled …
Long-Term Forest Soil Warming Alters Microbial Communities In Temperate Forest Soils,
2015
University of Massachusetts, Amherst
Long-Term Forest Soil Warming Alters Microbial Communities In Temperate Forest Soils, Kristen M. Deangelis, Grace Pold, Begum D. Topcuoglu, Linda T. A. Van Diepen, Rebecca M. Varney, Jeffrey L. Blanchard, Jerry Melillo, Serita D. Frey
Faculty Publications
Soil microbes are major drivers of soil carbon cycling, yet we lack an understanding of how climate warming will affect microbial communities. Three ongoing field studies at the Harvard Forest Long-term Ecological Research (LTER) site (Petersham, MA) have warmed soils 5°C above ambient temperatures for 5, 8, and 20 years. We used this chronosequence to test the hypothesis that soil microbial communities have changed in response to chronic warming. Bacterial community composition was studied using Illumina sequencing of the 16S ribosomal RNA gene, and bacterial and fungal abundance were assessed using quantitative PCR. Only the 20-year warmed site exhibited significant …
A Pan-Arctic Synthesis Of Ch4 And Co2 Production From Anoxic Soil Incubations,
2015
University of New Hampshire, Durham
A Pan-Arctic Synthesis Of Ch4 And Co2 Production From Anoxic Soil Incubations, Claire C. Treat, Susan M. Natali, Jessica G. Ernakovich, Colleen M. Iversen, Massimo Lupascu, Anthony David Mcguire, Richard J. Norby, Taniya Roy Chowdhury, Andreas Richter, Hana Santruckova, Christina Schadel, Edward A. G. Schuur, Victoria L. Sloan, Merritt R. Turestsky, Mark P. Waldrop
Faculty Publications
Permafrost thaw can alter the soil environment through changes in soil moisture, frequently resulting in soil saturation, a shift to anaerobic decomposition, and changes in the plant community. These changes, along with thawing of previously frozen organic material, can alter the form and magnitude of greenhouse gas production from permafrost ecosystems. We synthesized existing methane (CH4) and carbon dioxide (CO2) production measurements from anaerobic incubations of boreal and tundra soils from the geographic permafrost region to evaluate large-scale controls of anaerobic CO2 and CH4 production and compare the relative importance of landscape-level factors (e.g., vegetation type and landscape position), soil …
Monitoring Soil Response To Decreasing Acidic Deposition In A Western Adirondack Tributary Over A 16 Year Period,
2015
University at Albany, State University of New York
Monitoring Soil Response To Decreasing Acidic Deposition In A Western Adirondack Tributary Over A 16 Year Period, Michael Robert Antidormi
Legacy Theses & Dissertations (2009 - 2024)
Abstract
Comparison Of Glucose, Fructose And Sucrose Amperometric And Thermal Sensors For Detection Of Carbohydrates In Living Plant Tissue,
2015
University at Albany, State University of New York
Comparison Of Glucose, Fructose And Sucrose Amperometric And Thermal Sensors For Detection Of Carbohydrates In Living Plant Tissue, Scott Mcadoo
Legacy Theses & Dissertations (2009 - 2024)
Ecologists currently cannot test concentrations of carbohydrates in sap in vivo. Testing carbohydrates with current technology would require destructive tissue sampling. The tissue sampling involves large amounts of time and money to collect and test. Aphids are an insect that can bypass a tree’s passive immune system and feed off a phloem region for weeks. A series of enzymatic biosensors could be used to detect the concentration changes of specific carbohydrates. A calcium chelant can be added to defeat a tree’s immune system like an aphid. The detection of three carbohydrates, fructose, glucose and sucrose are involved in this study. …
Long-Term Litter Decomposition Controlled By Manganese Redox Cycling,
2015
Old Dominion University
Long-Term Litter Decomposition Controlled By Manganese Redox Cycling, Marco Keiluweit, Peter Nico, Mark E. Harmon, Jingdong Mao, Jennifer Pett-Ridge, Markus Kleber
Chemistry & Biochemistry Faculty Publications
Litter decomposition is a keystone ecosystem process impacting nutrient cycling and productivity, soil properties, and the terrestrial carbon (C) balance, but the factors regulating decomposition rate are still poorly understood. Traditional models assume that the rate is controlled by litter quality, relying on parameters such as lignin content as predictors. However, a strong correlation has been observed between the manganese (Mn) content of litter and decomposition rates across a variety of forest ecosystems. Here, we show that long-term litter decomposition in forest ecosystems is tightly coupled to Mn redox cycling. Over 7 years of litter decomposition, microbial transformation of litter …
Dissolved Oxygen Dynamics During A Phytoplankton Bloom In The Ross Sea Polyna,
2015
Old Dominion University
Dissolved Oxygen Dynamics During A Phytoplankton Bloom In The Ross Sea Polyna, Bastien Y. Queste, Karen J. Heywood, Walker O. Smith Jr., Daniel E. Kaufman, Timothy D. Jickells, Michael S. Dinniman
CCPO Publications
The Ross Sea polynya is one of the most productive regions in the Southern Ocean. However, limited access and high spatio-temporal variability of physical and biological processes limit the use of conventional oceanographic methods to measure early season primary productivity. High-resolution observations from two Seagliders provide insights into the timing of a bloom in the southern Ross Sea polynya in December 2010. Changes in chlorophyll and oxygen concentrations are used to assess bloom dynamics. Using a ratio of dissolved oxygen to carbon, net primary production is estimated over the duration of the bloom showing a sensitive balance between net autotrophy …
Chesapeake Bay Nitrogen Fluxes Derived From A Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, And Nitrogen Bonds,
2015
Old Dominion University
Chesapeake Bay Nitrogen Fluxes Derived From A Land-Estuarine Ocean Biogeochemical Modeling System: Model Description, Evaluation, And Nitrogen Bonds, Yang Feng, Marjorie A.M. Friedrichs, John Wilkin, Hanqin Tian, Qichun Yang, Eileen E. Hofmann
CCPO Publications
The Chesapeake Bay plays an important role in transforming riverine nutrients before they are exported to the adjacent continental shelf. Although the mean nitrogen budget of the Chesapeake Bay has been previously estimated from observations, uncertainties associated with interannually varying hydrological conditions remain. In this study, a land-estuarine-ocean biogeochemical modeling system is developed to quantify Chesapeake riverine nitrogen inputs, within-estuary nitrogen transformation processes and the ultimate export of nitrogen to the coastal ocean. Model skill was evaluated using extensive in situ and satellite-derived data, and a simulation using environmental conditions for 2001-2005 was conducted to quantify the Chesapeake Bay nitrogen …
Fine-Scale Plant Species Identification In A Poor Fen And Integration Of Techniques And Instrumentation In A Classroom Setting,
2015
University of New Hampshire - Main Campus
Fine-Scale Plant Species Identification In A Poor Fen And Integration Of Techniques And Instrumentation In A Classroom Setting, Dylan Schiff
Honors Theses and Capstones
Refining carbon flux measurements in the carbon cycle is an ongoing challenge. This study attempted to identify plant species in Sallie’s Fen, a nutrient-poor fen in Barrington, New Hampshire, at a fine scale in order to better model and understand carbon exchange between plants and the atmosphere in this type of ecosystem. A protocol for estimating percent cover of species in plots via ground measurements was developed. The next stage of this project was to compare these measurements with measurements derived from spectral images using ImageJ computer software. Statistical tests of the ground measurement data revealed that patterns of seasonal …
Spectroscopic Characterization Of Oceanic Dissolved Organic Matter Isolated By Reverse Osmosis Coupled With Electrodialysis,
2015
Old Dominion University
Spectroscopic Characterization Of Oceanic Dissolved Organic Matter Isolated By Reverse Osmosis Coupled With Electrodialysis, John R. Helms, Jingdong Mao, Hongmei Chen, E. Michael Perdue, Nelson W. Green, Patrick G. Hatcher, Kenneth Mopper, Aron Stubbins
Chemistry & Biochemistry Faculty Publications
Oceanic dissolved organic matter (DOM) is one of the largest pools of reduced carbon on Earth, yet DOM remains poorly chemically characterized. Studies to determine the chemical nature of oceanic DOM have been impeded by the lack of efficient and non-fractioning methods to recover oceanic DOM. Here, a DOM fraction (~40 to 86% recovery) was isolated using reverse osmosis/electrodialysis (RO/ED) and analyzed by solid-state 13C nuclear magnetic resonance (NMR) spectroscopy. Samples were obtained from biogeochemically distinct environments: photobleached surface gyre, productive coastal upwelling zone, oxygen minimum, North Atlantic Deep Water, and North Pacific Deep Water. A ubiquitous ‘background’ refractory …
Biogeochemical Cycling In Lake Superior Tributaries: Seasonality, Quantity And Quality Of Export,
2015
Michigan Technological University
Biogeochemical Cycling In Lake Superior Tributaries: Seasonality, Quantity And Quality Of Export, Ashley Anne Coble
Dissertations, Master's Theses and Master's Reports - Open
Seasonal and spatial variability in environmental factors may affect dissolved organic matter composition and nutrient transformation and retention in streams. The objective of this research was to quantify and describe seasonality, quantity, and quality of nutrient processing and export of ammonium (NH4), soluble reactive phosphate (SRP), and dissolved organic carbon (DOC) into Lake Superior through intensive study in a small 1st order watershed coupled with snapshot measurements across 12 tributaries that varied in size, location, and wetland coverage. Our results suggest biodegradable C is exported from a small headwater stream year-round and that DOC mineralization rates can be …
Origins Of Life On Earth: Mineral Effects On Vesicle Formation And Permeability,
2015
University of Akron Main Campus
Origins Of Life On Earth: Mineral Effects On Vesicle Formation And Permeability, Jacob Morris
Williams Honors College, Honors Research Projects
Understanding how life could have emerged on Earth is a very old problem that is still far from being resolved. Minerals have long been proposed to play a role in the formation of the first cell, but only few experimental data were reported concerning the mineral-lipid interactions. In the present work, calcein leakage assay, a fluorescence based experiment, and dynamic light scattering measurements were used to examine the effects of mineral properties and of MgCl2 on the formation and the stability of vesicles formed from single-chain amphiphiles (SCA), which are believed to have been present on early Earth. The …
