G. Philip Robertson - US grants

This project will initiate a long-term integrated study of interactions among organisms in agricultural ecosystems. The general goal is to test the hypothesis that management based on ecological concepts can effectively substitute for reliance on chemical subsidies in production-level agronomy. By imposing a range of management treatments on a series of experimental plots specific hypotheses will be tested that follow from the general hypothesis that nutrient subsidies can be minimized by manipulating plant-microbe interactions; that herbicide subsidies can be minimized by manipulating crop-weed interactions; and that pesticide subsidies can be minimized by manipulating plant- insect-pathogen-vertebrate interactions. Primary experimental treatments are designed to alter radically the controls on population-level interactions in agronomic systems. This will allow the testing of hypotheses about how long-term interactions among populations affect system- wide attributes such as nutrient availability, herbivory and pathogenesis, plant competition, and systemswide carbon allocation and nutrient/pesticide outputs. Treatments will include four main species-levels with two management levels nested within each: conventional corn/soybean cultivation (moldboard plowed vs. no-till), organic-based, low-input corn/soybean/cover cultivation (minimum chemical input vs.zero chemical input); short-rotation Populus (woody biomass) cultivation (above ground allocation vs. belowground allocation); and native successional vegetation (historically-tilled vs. never-tilled). These treatments will be established within the same general area, and the development of these systems will be followed indefinitely. Selected satellite sites in other portions of the landscape will also be examined to formulate a basis for addressing landscape-level questions in later phases of the project. Many would assert that the future of modern agriculture demands a basic, mechanism-level understanding of the ecology of production-level cropping systems. This endeavor requires a multidisciplinary, long-term approach at a site that is relevant to North American agronomy and that can provide the logistical support and administrative infrastructure to facilitate this type of major research effort. The project team for this research is excellent comprising a broad and appropriate array of expertise and very productive records of past performance. Institutional facilities are excellent at both the main campus and at the Kellogg Biological Station (KBS) field site. Institutional commitment to the project is substantial, both as direct support and in kind. It is expected that this project will rapidly establish itself as an invaluable collaborator within the extant family of related projects and that it will provide an instructive suite of comparisons for work on unmanaged, natural ecosystems. A large number of other related research projects will continue to be conducted at the KBS and will both benefit from and lend strength to this new work. It is recommended that this new, five-year continuing award be made as requested.

The investigators propose to study the interactions of key nutrient cycling processes in terrestrial ecosystems. The main objectives of this research are to examine the effects of different temporal interactions on nutrient availability in agricultural ecosystems and to examine the dynamics of these interactions within the soil profile. Specific to the newly proposed research are 1) a focus on water as a primary determinant of nutrient turnover; 2) a focus on soil pores of biological origin as regulators of water movement in the soil profile; 3) a focus on specific pathways of N loss from the system, and 4) a focus on quantitative modeling. Hypotheses about interactions among processes at several different scales will be tested. Soil lysimeters will be installed for tilled, no-tilled, and never tilled agricultural plots. 15N will be used to examine seasonal dynamics. Several replicated soil catenas sites will be used to address questions related to spatial variation in N turnover for plants, microbial biomass and inorganic N pools. Initially at these sites the PI's will track wetting fronts, root turnover, and soil solution concentrations of biologically important ions. Simulation modeling will be used to build a quantitative predictive models of how these processes interact to regulate nutrient availability to plants in a landscape perspective. The investigators are well qualified to perform the proposed research and the facilities at the Kellogg Center are more than adequate.

This Small Grant for Exploratory Research will extend a model- based reasoning approach (Functional Reasoning) to large-scale biogeochemical modeling. Functional Reasoning is a methodology for device knowledge capture. Because it has the potential for allowing complex systems to be modeled from a quantitative, top-down perspective, it is ideally suited for addressing recalcitrant problems in biology in which more is known about the end result (e.g. atmospheric concentrations of biogenic trace gases) than is known about the biological interactions giving rise to the end result. Before Functional Reasoning can be used in real world settings, a method to allow simulation of highly interactive sub-systems of devices must be developed. This is the objective of the work. This research is interdisciplinary (between Computer Science and Ecological Modeling). It will provide a theoretical approach for attacking very pressing problems such as issues of global change.

This project focuses on the role of soil-stream interfaces as control-points for the speciation (NO3-vs. NO2-vs. NH4+vs. DON vs. N2O) and flux of N in a heterogeneous landscape. Biogeochemical transformations of N at the soil-stream interface may have important effects on both the quantity and quality (speciation) of N lost to downstream ecosystems, and may modify the extent to which h the chemistry of watershed streams are affected by watershed processes. A mechanistic understanding of such N transformations along soil-stream flowpaths may therefore be critical in order to predict how watershed disturbances (both short-term and chronic) will affect surface-water chemistry. Preliminary studies from the Augusta Creek Watershed have pointed to soil-stream interfaces as potential control-points for downstream speciation and flux of N. The work outlined in this project seeks to provide an understanding of rates and mechanisms of N transformations along explicit soil-stream hydrologic flowpaths in the watershed. The principal investigators will use both descriptive and experimental approaches, including the use of tracers of hydrologic flowpaths (LiBr) and tracers for specific biogeochemical reactions (stable N isotopes). The main goal is to understand how patterns of N transformations at soil-stream interfaces vary in space, time,and as a function of hydrology.

In 1987 a Long-Term Ecological Research Project in Agricultural Ecology was initiated to examine basic ecological relationships in row crop ecosystems typical of the U.S. Midwest. The project's original goal was to test the basic, long-term hypothesis that agronomic management based on knowledge of ecological interactions in cropping systems can effectively replace management based on chemical subsidies. The same overall goal guides the project today. In order to test this hypothesis an experimental site was established in which different cropping systems, corresponding to different levels of agronomic/ecological disturbance, are used to test a series of working hypotheses. Working hypotheses are built around the general topic areas of nutrient availability/ retention, plant competition, and consumer (insect, pathogen) dynamics. Over the initial award period substantial progress has been made towards meeting the short-term goals of establishing a secure agricultural research site with long-term potential, of putting in place an integrated sampling program to address important long-term questions in both ecology and agronomy, and most importantly, of testing and refining the initial hypotheses. In this new project period the aim is to extend plot-based research to the regional landscape and to address seven basic ecological hypotheses that are critical for understanding the ecological underpinnings of modern agriculture and for providing the knowledge needed to sustain future agricultural production.

9311380 Robertson This proposal will examine the effect of environmental factors and diversity of denitrifying bacteria on the spatial and temporal variability of denitrification in agricultural and grassland ecosystems. Specific questions to be addressed include 1) to what extent, and under what circumstances, is denitrifier community composition different among ecosystems with different nitrous oxide production potentials?, 2) do denitrifiers from different ecosystems produce nitrous oxide at different rates?, and 3) does spatial and temporal variability in nitrous oxide production reflect differences in dominant denitrifier populations as well as differences in environmental controls? These questions will be addressed by sampling soil from ecosystems that differ in chemical conditions that affect nitrous oxide flux rates, incubating to characterize nitrous oxide flux rates, and denitrifier isolation to characterize community structure. %%% Denitrifiers are bacteria that, during anaerobic respiration, convert nitrogen from a form available to plants to gaseous nitrous oxide not available to plants. Thus, denitrifiers have a direct impact on soil fertility and plant production. Denitrification also is important because the nitrous oxide is an important greenhouse gas and a catalyst of statospheric ozone decay. Environmental factors affecting denitrification processes have been examined, but their relative importances and the significance of particular denitrifier species composition is not known. This study will all evaluation of the relative contributions of environmental controls and denitrifier diversity to nitrous oxide flux rates. ***

9510044 Paul Ecosystem Response to Catastrophic Defoliation of Poplars Defoliation of hardwood forests by Gypsy moth caterpillars in the eastern US has caused great concern. Defoliation kills some trees and the leafless trees are unsightly, as well as having the potential to cause environmental pollution because of the frass produced. Poor success of past attempts to stop defoliation, the patchiness of Gypsy moth attacks, and the various rates of recovery of different forests show there are numerous ecosystem responses and controls which are little known. Better knowledge of ecosystem response and recovery could greatly aid in coping with or overcoming catastrophic defoliation. This project will study a well characterized research plot where some trees will be defoliated and others protected using an organic insecticide. Effects on nitrogen cycling, water uptake, and root mycorrhizae will be measured. This project will provide the fundamental information which will help better manage forests affected by this serious pest.

9701765 Robertson While the loss of organic carbon and nitrogen via soluble forms has implications both for source and sink ecosystems, the extent and magnitude of fluxes are poorly known. Preliminary data from a range of ecosystems in an agricultural landscape in southwest Michigan suggest that fluxes of dissolved organic nitrogen can be quite significant. A review of the literature on leaching of soluble organic carbon and nitrogen, primarily studied in forests, suggests only abiotic controls. Several biotic controls are proposed here, given their large effect on the abiotic controls shown to significantly affect leaching of dissolved organic carbon and nitrogen(DOM). To better understand controls, an idea of the source of the leached DOM is critical. This study proposes a two tiered approach to looking at both aspects. A broad study of different ecosystems along a successional gradient and an intense study using isotopic tracers on the sources of leached DOM in one ecosystem. It is hypothesized that those factors which influence hydraulic flux will have the greatest effect on the mass loss of C and N through leached organic forms.

9810220
Robertson

Agricultural activities worldwide are carried out through a combination of biological and chemical management practices. The Kellogg Biological Station (KBS) Long-Term Ecological Research program has been conducting research since 1987 focusing on testing the hypothesis that agronomic management practices based on knowledge of ecological interactions can effectively replace management based on chemical subsidies. Work to test this general hypothesis is focused on field-crop ecosystems that are used extensively throughout the US Midwest. KBS research employs a series of sites where 11 different cropping systems and successional communities have been established to represent different levels and types of ecological disturbance. Within this series of sites, working hypotheses are being tested in general areas of soil microbial communities, the dynamics of insect consumers, nutrient availability, and plant community dynamics.
Recent work has led to development of biologically based agricultural systems that produce acceptable crop yields. The KBS site has documented changes in abundance of various taxa that appear to be important in row-crop function and in ecosystem-level attributes of agricultural systems. General ecological understanding has been advanced in key relationships in field-crop ecosystems. In addition to continuing these efforts, proposed work will evaluate the effects of agricultural practices at scales larger than individual fields on the dynamics of biogeochemical processes in entire watersheds. Efforts will also be developed to incorporate a social component to evaluate the degree to which human decision making plays critical roles in the ecological processes occurring in agricultural ecosystems. Finally, the results of efforts at the KBS site will be regionalized to develop a general understanding of the interactions between climate and productivity across the entire North Central Region.

0079573
Ostrom

This award provides seventy-percent partial funding support for the acquisition of mass spectrometry instrumentation to be installed and operated in the Environmental Isotope Geochemistry Laboratory at the Michigan State University. The University is committed to providing the remaining funds necessary for the acquisition of the instruments. The mass spectrometers will be used in basic and applied research projects aimed at improved understanding of interactions between the biosphere, atmosphere, and hydrosphere. The instrumentation will also be employed in laboratory technique courses at Michigan State University.
***

Soil aggregates, groups of soil particles bound together into a larger structural unit, may be important regulators of carbon and nitrogen cycling in soil. Aggregates physically protect organic matter from microbial oxidation and provide microsite habitats that may favor greenhouse gas production. Aggregate structure is typically lost following soil disturbances such as tillage, and the recovery of aggregate structure could help mitigate environmental problems related to carbon and nitrogen cycling. Accelerated carbon and nitrogen transformations in disturbed ecosystems contribute to a number of environmental problems, including greenhouse gas accumulation, groundwater contamination, and soil erosion.

This research will examine soil aggregation and its effects on carbon and nitrogen cycling in ten ecosystems on the same soil series along a disturbance gradient. The systems range from intensively managed, row crop agriculture to late successional forests. The research will test hypotheses about the recovery and breakdown of aggregates on soil carbon storage, trace gas fluxes, and microbial population structure.

This proposal envisions a model partner-based system that provides lead teachers both school-based workshops and a summer institute for science content. The model has three components: a science pedagogy part provided by science education faculty, a science content component provided by active research scientists and a classroom teaching component.

The specific goals are to deepen teachers understanding of content, scientific inquiry and pedagogy, including curriculum and assessment strategies; to develop a group of sixty teacher leaders and to provide teachers access to effective applications of educational technology.

Renovation of laboratory instrumentation at the Kellogg Biological Station

A grant has been awarded to Michigan State University under the direction of Drs. G. Philip Robertson and Stephen K. Hamilton to renovate crucial instrumentation used for environmental research at the University's W.K. Kellogg Biological Station (KBS). The instruments will provide an improved abililty to quantify carbon, nitrogen, phosphorus, and other elements in plant, soil, and water samples from various ecosystems around the Station. The new instruments will replace existing ones that are either worn out or obsolete, improving both analytical sensitivity and sample throughput. Many on-going studies, funded by both state and federal agencies at KBS, depend on access to high-quality analytical facilities; the new instruments will fill a major emerging gap in the Station's analytical capacity.

Both biogeochemical and ecological research will benefit from the acquisition. Scientific questions to be addressed with the new instrumentation have broad environmental significance. For example, excess nitrogen and phosphorus in the environment are known to harm ecosystems for which they were not intended, with substantial economic impact. A recent economic study placed the costs of these pollutants in the tens of billions of dollars per year for water quality alone; better knowledge of how nitrogen, phosphorus, and carbon cycle in complex landscapes should allow the development of more effective management strategies.

Access to high-quality instrumentation is also important for graduate and undergraduate education. KBS is an important environmental teaching facility at MSU and students will use these instruments both in field courses and for their own independent study projects. Additionally the instruments are used in outreach and community education activities - the Four-Township Water Resources Council and the Augusta Creek Watershed Association have both used data from water samples analyzed by KBS laboratories, and the Station also partners with a group of K-12 science teachers who have used the existing instruments in summer science institutes. At a number of levels, then, this NSF award will have a positive impact on environmental research, education, and outreach.

The Kellogg Biological Station (KBS) LTER project was initiated in 1987 and since then has provided experimental and observational research designed to understand the basic internal ecological relationships that control productivity of field crop ecosystems in North America, independent of external inputs such as pesticides and fertilizers. The project has combined comparative and experimental studies of various cropping systems and unmanaged successional communities to provide ecological knowledge that can direct efficient agronomic management. This project will continue that long-term line of research and will expand it to address understanding and valuation of ecosystem services. This LTER renewal project develops an enlarged conceptual framework that integrates regional watershed and social context into the causes-consequences of changing agricultural ecology and economy.

This project contributes to understanding of the structure, function, and dynamics of agricultural ecosystems, advancing understanding of the ecological interactions that underpin productive, sustainable, low-impact agriculture. It assembles and integrates valuable long-term data sets on climate, hydrology, biology, ecology, biogeochemical processes, and other elements of the local and regional ecosystems. The project has broad societal value through its contributions to improved management of agricultural ecosystems. Its broader values also include extensive research-based training, educational program development and K-12 teacher training, and strong and diverse outreach to the public and to policy-makers.

ABSTRACT
Proposal: DBI-0507925

An award has been made to Utah State University under the direction of Dr. Todd Crowl and colleagues, Dr. David Breshears, Arizona State University, and Dr. Philip Robertson, Michigan State University, to support the efforts of the Consortium of Regional Ecological Observatories (COREO) in the of formulation of regional activities that will support national questions that will ultimately drive the National Ecological Observatory Network (NEON). The sixteen regional groups that gave rise to COREO formed institutional collaboratives, assessed regional resources, and formulated regional research agendas. The overall goal of COREO is to engage the broader scientific, educational, and engineering communities in an organized set of activities that will formulate the regional perspective regarding the organization and question-driven design of the NEON. The participation of regional groups will assure that the infrastructure design addresses the regionally varying drivers and provides the capacity to address questions at regional scales. The COREO organization, workshops, assessments, and web site will provide a structured process to aid in the design of a national research platform that will transform ecological science by providing innovative infrastructure that will permit questions of national significance to be addressed at regional to continental scales. COREO will play an integral role in the iterative, web-based process of NEON plan development. COREO will inform and participate in the NEON Design Consortium planning process and provide essential assessments that identify, organize, and summarize existing data, infrastructure, and intellectual resources available to support the NEON design and implementation. Further, COREO will engage decision makers, agencies, and administrators in the broader NEON design process. Finally, the proposed efforts will provide a forum to create collaboratives that design regional to national scale science that will be dependent on the NEON research platform.

Non-technical Summary:
AOC-Ecosystem Services from Low-input Cropping Systems:
Incentives to Produce Them and Value of Consuming Them
PIs: Scott M. Swinton, Frank Lupi, G. Philip Robertson, Michigan State University

NSF-supported scientists have identified a low-input rotation of corn, soybean and wheat that offers not only good crop yields, but also environmental benefits including improvements in water quality, soil quality, climate stability and beneficial insect populations. However, this low-input crop rotation is not widely adopted by farmers. In order to find out why, researchers at the Long-Term Ecological Research Site in Agricultural Ecology will check to see if the benefits can be scaled up from experimental plots to farm fields. They will also host farmer focus groups to find out what farmers know and believe about the low-input crop rotation. Through a pair of mail surveys, researchers will explore what incentives farmers might need to adopt an environmentally beneficial crop rotation and what incentives citizens would be willing to provide to get the associated environmental benefits.
This research will help guide policies to encourage farmers to provide a wider range of ecosystem services. Its collaboration between ecologists and economists will improve scientists' understanding of how human and ecological systems interact.

The use of nitrogen fertilizers has dramatically increased food production globally. Nonetheless, nitrogen fertilizer use can also have negative impacts on water, air, and soil quality. Many of the processes that regulate nitrogen movement in ecosystems have been determined; however, environmental heterogeneity makes predicting the behavior of these processes in the field difficult. To date, strategies to examine nitrogen cycle processes have largely ignored the role of spatial heterogeneity for regulating important processes such as soil organic matter decomposition and its associated nitrogen release. This proposal seeks to better understand how heterogeneity affects soil microbial processes, plant root growth, and nitrogen acquisition by plants. Results from this research will add significant insight into predictions of biogeochemical cycling rates in complex systems. They will also aid outreach efforts in K-12 science teacher training and agricultural land management in the southern Michigan area.

This proposal describes a Track 1 project designed to bring inquiry-based learning to schools in rural Michigan. Eight graduate Fellows will connect with teachers to learn pedagogical skills and bring ecological concepts to schools. Eleven Faculty at Kellogg Biological Station will be involved in several aspects of the project.

This award provides partial support for construction of a small (approximately 2500 sq.ft.) building at the W.K. Kellogg Biological Station (KBS) to be used for a number of field research and education-related activities. Principal among these is the sorting and preparation of field samples prior to analysis. Soil, plant, insect, vertebrate, and aquatic samples would be sorted, processed and consolidated prior to analysis in analytical laboratories located about 2 Km. away in the main KBS academic building. In addition to this, the new building would also provide sample archive space and flexible classroom space for presentations to students, visiting environmental professionals, journalists and the public prior to visits to field research sites located within walking distance of the building. The structure will also be used to house computer and communications equipment for existing and new sensors to be deployed at an adjacent field site. KBS, which is the largest off-campus unit of Michigan State University, is one of a number of major field research stations in the U.S. that have had a long-term impact on ecological research and training. The Station has a significant record of research, education, and outreach in ecology and evolutionary biology, and is known as a premier field site for work in the successional plant communities, freshwater habitats, and agricultural landscapes that are typical of the upper U.S. Midwest. Research activity by resident and visiting researchers at KBS has grown over the past 15 years to the point that space resources are very stretched. The new building will enhance the ability of KBS to provide the best possible research, training, and outreach in ecology and evolutionary biology for resident and visiting researchers and students, while also providing a unique classroom/laboratory teaching facility for field-based classes, short-courses, workshops, and a major K-12 secondary science teacher trainingproject at KBS.

Abstract: Using the STEM Dimensions of Bioenergy Sustainability
to Bring Leading-edge Graduate Research to K-12 Learning Settings.

The intellectual focus of this new GK-12 project at the W.K. Kellogg Biological Station (KBS) is on the ecological dimensions of bioenergy sustainability. Graduate students in Michigan State University?s Ecology, Evolutionary Biology & Behavior and Environmental Science & Public Policy programs who are engaged in STEM research at KBS will partner with teachers in the KBS K-12 Partnership for Science Literacy, the new Department of Energy Great Lakes Bioenergy Research Center (GLBRC), and the NSF Long-Term Ecological Research (LTER) project on the Ecology of Agricultural Landscapes. Project activities include establishing schoolyard science research plots in K-12 Partner districts that mimic aspects of GLBRC research plots and serve as the foundation for a schoolyard research network. Fellows will work collaboratively with each other, their advisors, and project partners to incorporate their own research into K-12 research and inquiry activities that address Michigan and national science education standards.

Fellows will improve their ability to place their research in its broader societal and global contexts, to collaborate across disciplines, to integrate their research and teaching, and to communicate their research to professional, K-12 and public audiences. The opportunity to work collaboratively with fellows on authentic research related to pressing national needs will enhance the professional development of the K-12 partner teachers and enrich the education of K-12 students. This project will also enhance ongoing efforts at KBS to recruit a greater number and diversity of young people into STEM science disciplines.

This doctoral dissertation improvement project will study the loss of nitrogen from soils to the atmosphere, a process called denitrification. Traditionally, denitrification was thought to occur mostly in surface soils, but recent evidence suggests that deeper soils can also play an important role in the nitrogen cycle. This project will conduct a series of experiments to assess the rates of denitrification from deep soils and how this affected by specific agricultural practices.

Denitrification represents one of the major pathways that biologically available nitrogen leaves terrestrial ecosystems, along with leaching, volatilization, and runoff, and is the only process capable of returning nitrogen to its inert form of dinitrogen gas. Understanding where and at what rate dinitrification occurs is fundamental to understanding the nitrogen cycle.

Nitrogen loss from corn farming in the Midwest is a major cause of water pollution and greenhouse gas emission. Focusing on farms in Iowa, Illinois, and Michigan, this project will address important gaps in our current understanding of the links between the decisions of corn farmers and the quality of water and air in the region. Researchers will refine previous work on nitrogen loss to take variability within farm fields into account, identify the factors that influence the decisions of farmers about fertilizer use, and develop an integrated, quantitative model that couples the natural dynamics of nitrogen cycling with the social and economic dynamics of farming.

Results from this project will help farmers and policy makers evaluate alternative ways to reduce water pollution and greenhouse gas emissions from Midwestern row crops. A Nitrogen Roundtable will bring researchers, managers, and stakeholders together, and the project will engage K-12 educators to disseminate research results to the public. The model to be produced is expected to provide a new decision-support tool for more sustainable agriculture in the U.S.

Nitrous oxide is the third most important greenhouse gas in the atmosphere, with an atmospheric lifetime of about 114 years and a global warming impact per molecule that is about 300 times greater than that of carbon dioxide. Atmospheric concentrations of nitrous oxide are increasing, primarily due to agriculture, which is thought to be responsible for about half of the total output to the atmosphere that can be attributed to human activities. Current trends in land-use change and agricultural intensification (in particular increasing fertilizer use) suggest that an additional 20% increase in global nitrous oxide emissions will occur by 2030. However, difficulties in measuring the output of nitrous oxide from ecosystems make it hard to manage and predict nitrous oxide production from major human sources. This project we will test a promising new technique to measure the ecosystem-level exchange of nitrous oxide with the atmosphere using a laser sensor. This novel approach will provide opportunities to measure whole system nitrous oxide dynamics at hourly to daily time scales over areas that are too large to effectively sample with traditional techniques. With this novel approach, a new understanding of the factors that control the production and consumption of nitrous oxide in forests, grasslands, and agricultural lands may be possible. This would lead to much better ability to manage and minimize the production of this important greenhouse gas, because management is currently hampered by significant uncertainties in the measurement of nitrous oxide.

A major barrier to understanding and mitigating emissions of nitrous oxide from agricultural and other managed soils is the difficulty with which fluxes are measured, given temporal and spatial variability that often exceeds an order of magnitude at scales of meters and hours. In this project, open-path quantum cascade laser sensors will be integrated with standard micrometeorological measurements to develop a solar-powered measurement system to quantify nitrous oxide fluxes. This novel approach will provide opportunities to measure whole system nitrous oxide fluxes at hourly to daily time scales over multi-hectare areas, and thereby resolve and integrate the spatial and temporal variability that makes this flux so difficult to quantify and model in situ. A newly developed open-path quantum cascade laser (OP-QCL) sensor will be used on each of two existing carbon dioxide micrometeorological eddy covariance towers to measure ecosystem-level nitrous oxide exchange. In addition to the OP-QCL sensors, multiple standard static chambers will be deployed within the study area to perform ground based validation of the OP-QCL measurements. One of the sensors will be deployed in a high-emission fertilized continuous corn system; the other will be deployed in grassland that has not been farmed for 25 years. In addition to validating the micrometeorological method, the project will test hypotheses related to the temporal variability of fluxes at diurnal to seasonal scales, which cannot be answered without continuous observations. Specific project objectives include 1) to develop, test, and validate an OP-QCL sensor for ecosystem-level measurements of nitrous oxide fluxes using micrometeorological towers; and 2) to relate and assess the significance of changes in nitrous oxide flux with temporal environmental variability, including daily, seasonal, and episodic events such as large rain events and management activities such as tillage and fertilization in cropped systems.

Agriculture is the dominant land use under direct management by people, and it is one of the biggest agents of global change, with far-reaching impacts on human welfare and the environment. The application of ecological knowledge to improve sustainable agricultural ecosystems remains a recognized grand challenge for environmental science. Since 1988, research at the W.K. Kellogg Biological Station (KBS) LTER has addressed this challenge for row-crop ecosystems and landscapes, by seeking to understand the fundamental ecological underpinnings of these highly managed ecosystems and to reveal ways that ecological knowledge can enhance the long-term sustainability of production agriculture. This renewal award builds on past work to launch an effort to better understand the long-term stability of key ecosystem services afforded by agriculture, with an emphasis on three major drivers: climate change, changes in the science of land management for crop production, and invasive species. Proposed research bears directly on agricultural and environmental management and policies at scales ranging from local to global. The study of agricultural systems also informs ecology because few other ecosystems have such a degree of simplification and control of major environmental drivers. Training graduate students and postdocs is an important component of this project, as is providing research experiences for undergraduates. KBS scientists also will continue to work with K-12 science teachers through an established partnership with 11 nearby school districts. Outreach and extension activities will reach a broad community of stakeholders, and will include a new emphasis on farmers and those who influence farmer decisions.

The major scientific foci of the KBS LTER are vulnerability and resilience of cropping systems to drivers of change, and how ecological theory can help design more sustainable crop production. Two overarching questions motivate the research: 1) How do changing environmental drivers affect the resilience of key ecosystem services including crop yield and profitability as well as environmental and socioecological benefits, and 2) To what extent can ecological knowledge help maintain the robust and reliable delivery of these services? Key ecosystem services include crop yield but also extend more broadly to climate stabilization (greenhouse gas emissions), water quality (eutrophication), pest suppression (insect herbivory and predation), and soil fertility (plant-microbe-soil interactions). Knowledge gaps identified from research to date will be addressed with new research lines that include rainfall manipulation experiments, watershed observations, and examinations of rapid evolution of plant-microorganism associations, predator-prey dynamics newly influenced by invasive species and novel pesticides, and long-term changes in farmer attitudes and behaviors.