Biogeochemistry Commons^™

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 …

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 …

The Ecologist's Field Guide To Sequence-Based Identification Of Biodiversity, Simon Creer, Kristy Deiner, Serita D. Frey, Dorota Porazinska, Pierre Taberlet, W. Kelley Thomas, Caitlin Potter, Holly M. Bik

Faculty Publications

The past 100 years of ecological research has seen substantial progress in understanding the natural world and likely effects of change, whether natural or anthropogenic. Traditional ecological approaches underpin such advances, but would additionally benefit from recent developments in the sequence-based quantification of biodiversity from the fields of molecular ecology and genomics. By building on a long and rich history of molecular taxonomy and taking advantage of the new generation of DNA sequencing technologies, we are gaining previously impossible insights into alpha and beta diversity from all domains of life, irrespective of body size. While a number of complementary reviews …

A Comparison Of Soil Hydrothermal Properties In Zonal And Uniform Tillage Systems Across The Us Corn Belt, 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

Zonal tillage (e.g. ridge tillage, RT) separates management of row and inter-row positions, while non-zonal tillage (e.g. chisel plough, CP) applies management uniformly across a field. This may have large effects on soil hydrothermal properties, affecting soil processes and crop development. We examined the effects of RT versus CP on soil hydrothermal conditions under maize (Zea mays L.) at four sites spanning the US Corn Belt over two growing seasons (2012–2013). We also investigated whether RT, as a result of changes in hydrothermal conditions, could stimulate greater soil nitrogen (N) availability during peak maize N demand. We captured wide variation …

Soil Functional Zone Management: A Vehicle For Enhancing Production And Soil Ecosystem Services In Row-Crop Agroecosystems, Alwyn Williams, Daniel A. Kane, Patrick M. Ewing, Lesley W. Atwood, Andrea Jilling, Meng Li, Yi Lou, Adam S. Davis, A. Stuart Grandy, Sheri C. Huerd, Mitchell C. Hunter, Roger T. Koide, David A. Mortensen, Richard G. Smith, Sieglinde S. Snapp, Kurt A. Spokas, Anthony C. Yannarell, Nicholas R. Jordan

Faculty Publications

There is increasing global demand for food, bioenergy feedstocks and a wide variety of bio-based products. In response, agriculture has advanced production, but is increasingly depleting soil regulating and supporting ecosystem services. New production systems have emerged, such as no-tillage, that can enhance soil services but may limit yields. Moving forward, agricultural systems must reduce trade-offs between production and soil services. Soil functional zone management (SFZM) is a novel strategy for developing sustainable production systems that attempts to integrate the benefits of conventional, intensive agriculture, and no-tillage. SFZM creates distinct functional zones within crop row and inter-row spaces. By incorporating …

Mycorrhizal Roots In A Temperate Forest Take Up Organic Nitrogen From 13c- And 15n-Labeled Organic Matter, Matthew A. Vadeboncoeur, Andrew P. Ouimette, Erik A. Hobbie

All Materials

Background and Aims

The importance of the uptake of nitrogen in organic form by plants and mycorrhizal fungi has been demonstrated in various ecosystems including temperate forests. However, in previous experiments, isotopically labeled amino acids were often added to soils in concentrations that may be higher than those normally available to roots and mycorrhizal hyphae in situ, and these high concentrations could contribute to exaggerated uptake.

Methods

We used an experimental approach in which we added ¹³C-labeled and ¹⁵N-labeled whole cells to root-ingrowth cores, allowing proteolytic enzymes to release labeled organic nitrogen at a natural rate, as …

Changes In Litter Quality Caused By Simulated Nitrogen Deposition Reinforce The N-Induced Suppression Of Litter Decay, Linda T. A. Van Diepen, Serita D. Frey, Christopher M. Sthultz, Eric W. Morrison, Rakesh Minocha, Anne Pringle

Faculty Publications

Rates of nitrogen (N) deposition are increasing in industrialized and rapidly developing nations. Simulated N deposition suppresses plant litter decay rates, in particular for low quality (high lignin) litter. Litter quality is a primary driver of litter decomposition; however, it is not clear how changes in litter quality caused by long-term ecosystem exposure to chronic N additions interact with altered soil N-availability to influence litter decay dynamics. To document the effects of simulated N deposition on litter quality, we conducted a meta-analysis of available litter nutrient data from simulated N deposition experiments in temperate forests. To directly test whether changes …

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 …

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 …

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, 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 …

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 …

Integrating Microbial Physiology And Physio-Chemical Principles In Soils With The Microbial-Mineral Carbon Stabilization (Mimics) Model, William R. Wieder, A. Stuart Grandy, Cynthia M. Kallenbach, Gordon B. Bonan

Faculty Publications

A growing body of literature documents the pressing need to develop soil biogeochemistry models that more accurately reflect contemporary understanding of soil processes and better capture soil carbon (C) responses to environmental perturbations. Models that explicitly represent microbial activity offer inroads to improve representations of soil biogeochemical processes, but have yet to consider relationships between litter quality, functional differences in microbial physiology, and the physical protection of microbial byproducts in forming stable soil organic matter (SOM). To address these limitations, we introduce the MIcrobial-MIneral Carbon Stabilization (MIMICS) model, and evaluate it by comparing site-level soil C projections with observations from …

Land-Use Legacies Regulate Decomposition Dynamics Following Bioenergy Crop Conversion, Cynthia M. Kallenbach, A. Stuart Grandy

Faculty Publications

Land-use conversion into bioenergy crop production can alter litter decomposition processes tightly coupled to soil carbon and nutrient dynamics. Yet, litter decomposition has been poorly described in bioenergy production systems, especially following land-use conversion. Predicting decomposition dynamics in postconversion bioenergy production systems is challenging because of the combined influence of land-use legacies with current management and litter quality. To evaluate how land-use legacies interact with current bioenergy crop management to influence litter decomposition in different litter types, we conducted a landscape-scale litterbag decomposition experiment. We proposed land-use legacies regulate decomposition, but their effects are weakened under higher quality litter and …

Mechanisms Of Soil Carbon Accrual And Storage In Bioenergy Cropping Systems, Lisa K. Tiemann, A. Stuart Grandy

Faculty Publications

Annual row cropping systems converted to perennial bioenergy crops tend to accrue soil C, likely a function of increased root production and decreased frequency of tillage; however, very little is known about the mechanisms governing the accrual and stability of this additional soil C. To address this uncertainty, we assessed the formation and stability of aggregates and soil organic C (SOC) pools under switchgrass, giant miscanthus, a native perennial grass mix and continuous corn treatments in Michigan and Wisconsin soils differing in both texture and mineralogy. We isolated different aggregate size fractions, >2 mm, 0.5–2 mm, and <0.5 mm, using a procedure intended to minimize alterations to aggregate biological and chemical properties. We determined SOC, permanganate oxidizable C (POXC), and microbial activities (i.e. enzyme activities and soil respiration rates) associated with these aggregates. Soil type strongly influenced the trajectory of aggregate formation and stabilization with differences between sites in mean aggregate size, stability, SOC and microbial activity under perennial vs. corn cropping systems. At the Michigan site, soil microbial activities were highest in the >2 mm aggregates, …

Effect Of Carex Rostrata On Seasonal And Interannual Variability In Peatland Methane Emissions, Genevieve L. Noyce, Ruth Varner, Jill L. Bubier, Steve Frolking

Earth Sciences

Peatlands are a large natural source of atmospheric methane (CH₄), and the sedge Carex rostrata plays a critical role in the production, oxidation, and transport of CH₄ in these systems. This 4 year clipping experiment examined the changes in CH₄ emissions from a temperate peatland after removing all aboveground C. rostrata biomass. Methane fluxes, dissolved CH₄, and environmental variables were measured during spring, summer, and fall from 2008 to 2011. Clipping and removing the C. rostrata leaves and stems caused an immediate decrease in CH₄ emissions that persisted over 4 years of this …

A Source Of Terrestrial Organic Carbon To Investigate The Browning Of Aquatic Ecosystems, Jay T. Lennon, Stephen K. Hamilton, Mario E. Muscarella, A. Stuart Grandy, Kyle Wickings, Stuart E. Jones

Faculty Publications

There is growing evidence that terrestrial ecosystems are exporting more dissolved organic carbon (DOC) to aquatic ecosystems than they did just a few decades ago. This “browning” phenomenon will alter the chemistry, physics, and biology of inland water bodies in complex and difficult-to-predict ways. Experiments provide an opportunity to elucidate how browning will affect the stability and functioning of aquatic ecosystems. However, it is challenging to obtain sources of DOC that can be used for manipulations at ecologically relevant scales. In this study, we evaluated a commercially available source of humic substances (“Super Hume”) as an analog for natural sources …

Mechanisms Of Nutrient Limitation And Nutrient Acquisition In Managed And Unmanaged Forest Ecosystems, Matthew A. Vadeboncoeur

Doctoral Dissertations

Understanding the interactions between global change, human and natural disturbances, and other factors on biogeochemical processes in forests is necessary to ensure the sustainability of forest management. Here I report the results of several investigations into nutrient acquisition processes in the forests of New Hampshire. I begin with a meta-analysis of fertilization studies showing that phosphorus (P) and calcium (Ca) as well as nitrogen (N) may limit primary production in deciduous forests of the region. Because these limiting nutrients are all removed from the ecosystem when trees are harvested, I compared nutrient budgets under a range of harvesting scenarios with …

Recovery From Disturbance Requires Resynchronization Of Ecosystem Nutrient Cycles, Edward B. Rastetter, Ruth D. Yanai, R Quinn Thomas, Matthew A. Vadeboncoeur, Timothy J. Fahey, Melany C. Fisk, Bonnie L. Kwiatkowski, Steven P. Hamburg

All Materials

Nitrogen (N) and phosphorus (P) are tightly cycled in most terrestrial ecosystems, with plant uptake more than 10 times higher than the rate of supply from deposition and weathering. This near-total dependence on recycled nutrients and the stoichiometric constraints on resource use by plants and microbes mean that the two cycles have to be synchronized such that the ratio of N:P in plant uptake, litterfall, and net mineralization are nearly the same. Disturbance can disrupt this synchronization if there is a disproportionate loss of one nutrient relative to the other. We model the resynchronization of N and P cycles following …

Cycling Of Molecular Hydrogen In Subarctic Sweden, Victoria Ward

Honors Theses and Capstones

No abstract provided.

Predicting Decadal Trends And Transient Responses Of Radiocarbon Storage And Fluxes In A Temperate Forest Soil, C. A. Sierra, S. E. Trumbore, E. A. Davidson, Serita D. Frey, K. E. Savage, F. M. Hopkins

Faculty Publications

Representing the response of soil carbon dynamics to global environmental change requires the incorporation of multiple tools in the development of predictive models. An important tool to construct and test models is the incorporation of bomb radiocarbon in soil organic matter during the past decades. In this manuscript, we combined radiocarbon data and a previously developed empirical model to explore decade-scale soil carbon dynamics in a temperate forest ecosystem at the Harvard Forest, Massachusetts, USA. We evaluated the contribution of different soil C fractions to both total soil CO2 efflux and microbially respired C. We tested the performance of the …

Phosphate Availability During Sediment Resuspension Events In The Great Bay Estuary, Taylor Langkau

Honors Theses and Capstones

Phosphate is an important nutrient to marine ecosystems such as the Great Bay Estuary. However, its bioavailability is limited due to its tendency to adsorb to marine sediments, especially iron oxides. This paper investigates phosphate dynamics during a simulated storm compared to calm conditions and aims to quantify the mechanisms of phosphate adsorption.

Permanganate Oxidizable Carbon Reflects A Processed Soil Fraction That Is Sensitive To Management, Steven W. Culman, Sieglinde S. Snapp, Mark A. Freeman, Meagan E. Schipanksi, Josh Beniston, Rattan Lal, Laurie E. Drinkwater, Alan J. Franzluebbers, Jerry D. Glover, A. Stuart Grandy, Juhwan Lee, Johan Six, Jude E. Maul, Steven B. Mirsky, John T. Spargo, Michelle M. Wander

Faculty Publications

Permanganate oxidizable C (POXC; i.e., active C) is a relatively new method that can quantify labile soil C rapidly and inexpensively. Despite limited reports of positive correlations with particulate organic C (POC), microbial biomass C (MBC), and other soil C fractions, little is known about what soil fractions POXC most closely reflects. We measured POXC across a wide range of soil types, ecosystems, and geographic areas (12 studies, 53 total sites, n = 1379) to: (i) determine the relationship between POXC and POC, MBC and soil organic C (SOC) fractions, and (ii) determine the relative sensitivity of POXC as a …

New Science, Synthesis, Scholarship, And Strategic Vision For Society, David R. Foster, Emery Boose, Elizabeth A. Colburn, Elizabeth E. Crone, Aaron M. Ellison, Clarisse Hart, Kathy Fallon Lambert, David A. Orwig, Julie Pallant, Pamela M. Snow, Kristina A. Stinson, Dianna L. Doucette, Paul R. Moorcroft, Andrew D. Richardson, J. William Munger, Adrien C. Finzi, Lucy Hutyra, Anne Short, Brian Donahue, Christopher A. Williams, William V. Sobczak, W. Wyatt Oswald, Edward K. Faison, Jerry M. Melillo, Jonathan R. Thompson, Jeffrey L. Blanchard, Elizabeth S. Chilton, Kristen M. Deangelis, Stephen Destefano, David B. Kittredge, Serita D. Frey, Scott V. Ollinger, Eric A. Davidson

Faculty Publications

Harvard Forest LTER (HFR) is a two decade-strong, integrated research and educational program investigating responses of forest dynamics to natural and human disturbances and environmental changes over broad spatial and temporal scales. HFR engages >30 researchers, >200 graduate and undergraduate students, and dozens of institutions in research into fundamental and applied ecological questions of national and international relevance. Through LTER I–IV, HFR has added historical perspectives, expanded its scope to the New England region, integrated social, biological, and physical sciences, and developed education and outreach programs for K-12, undergraduate, and graduate students, along with managers, decision-makers, and media professionals.

No-Net-Loss Not Met For Nutrient Function In Freshwater Marshes: Recommendations For Wetland Mitigation Policies, Katie Hossler, Virginie Bouchard, M. Siobhan Fennessy, Serita D. Frey, Evelyn Anemaet, Ellen Herbert

Faculty Publications

Wetlands provide many important services throughout the world, with an estimated economic value that, in comparison to other ecosystems, far exceeds their relatively small global extent. In recognition of their importance, both national and international regulations exist to protect the world's remaining wetlands. Of growing interest is the “no-net-loss” policy which permits unavoidable destruction of wetlands if compensated by restoration of degraded wetlands or creation of new wetlands. The fundamental assumption of no-net-loss is that wetlands can be created which function equivalently to natural wetlands. One integral function that wetlands perform is cycling of carbon, nitrogen and phosphorus. Here we …

Root Production And Methane Dynamics: Impact Of Wetland Functional Group Diversity And Composition, Rachel Schultz, Virginie Bouchard, Serita D. Frey

Faculty Publications

Background/Question/Methods: The loss of biodiversity worldwide has prompted a close investigation of the link between diversity and ecosystem functions. Most experimental studies have looked at the relationship between grassland plant diversity and aboveground productivity. Less is known about other ecosystems or how diversity affects belowground processes. Our objective was to investigate the link between plant community (diversity and composition) and key belowground processes such as root biomass production and CH4 dynamics in wetland ecosystems. We hypothesized that 1) root biomass would increase with functional group diversity due to complementarity and 2) the sediment pool of CH4 would decrease with diversity …