Research Projects

Microplastics including nanoplastics will be extracted and collected from the samples of soil, water, plant and other organisms using the published procedures (with modifications when needed). Then, microplastics will be identified and examined for polymer types, shapes, sizes and quantity by LDIR, FTIR, Raman, TEM, SEM and other instruments. Plant uptake of contaminants from water and soil will be assessed using greenhouse experiments. We will also investigate the beneficial uses of engineered nanomaterials and biochars in agriculture using both hydroponic and soil-based experiments in greenhouse and in remediation using both soil and water.

1-The issue under investigation in this proposal is important because reproductive performance in beef and dairy cattle is often suboptimal resulting in increased intervals to conception and/or rebreeding failures that collectively reduce farm revenues due to decreased milk production or calf production efficiencies. Therefore, approaches that facilitate conception and increase conception rates will benefit the farmer and the economy in general.

2-The Umass research groups in this grant, Drs. Fissore and Visconti will be focused on two of the three Objectives,

Objective 1: Identify Mechanisms that Regulate Ovarian Function and Oocyte Quality during the Estrous Cycle.

Objective 2: Determine Factors Associated with Fertilization, Embryo Development, and Conceptus-Endometrial Interactions that Dictate Pregnancy Success.

3-Colleagues working in fertilization, embryo development, and fertility in mammalian species including humans, post-docs and graduate students, technicians, undergraduate students, embryologists, and producers.  

4-Oocyte quality is of one the parameters affected in high milk-yield cows. Therefore, examining how specific molecules and mechanisms might be downregulated or inactivated in those animals will improve the quality of the oocytes and their developmental potential such that a higher proportion of the fertilized oocytes and early embryos can progress to implantation and term-pregnancy. A second area is to prepare the sperm for fertilization akin to what happens in the female reproductive tracts. We plan to pre-treat bull sperm prior to adding it to oocytes or females. Recent studies from the Visconti lab show that changing the metabolic status of mouse sperm prior to fertilization can enhance post-fertilization outcomes, including embryo development and implantation success. We will extend these to the bovine sperm and embryos.

Legumes are important agricultural and feed crops second only to cereal crops. Grain legumes such as chickpea, lentils and the common bean provide 33 % of human dietary protein and up to 60 % in developing countries (Gentzbittel et al. 2015). Soybeans and alfalfa are important for animal feed and fodder as well as intercropping systems because of their ability to fix nitrogen. Because of their agronomic, nutritional and environmental benefits, it is imperative to understand factors that may influence agricultural yield and/or quality of feed.

Plants produce a diverse array of specialized metabolites to ensure adaptation to their ecological niche by functioning in pollinator attraction, herbivore repellence and pathogen resistance (Gershenzon and Dudareva 2007). Terpenes, a major class of specialized metabolites, play an important role in gene-by-environment interactions as shown in crops like rice and maize (Murphy and Zerbe 2020).

Terpenes have been well described in their response to biotic factors. However, comparatively fewer investigations have been performed for abiotic stress. In the changing face of climate, where heat, nutrients, and water all become important factors influencing agricultural productivity and food security, it is essential to understand the chemical response strategy employed in response to abiotic stressors. In this proposal, we will investigate the chemical response strategy (focusing on the terpenome) of Medicago truncatula to select abiotic conditions.

We designed full-size field trials to test the effectiveness of sorghum-maize intercropping at the UMass Crop and Animal Research and Education Farm in South Deerfield, MA. Plots of sorghum monocrop and maize monocrop served as controls with two intercropping systems, alternating row and mixed seeding intercropping. All four planting treatments were coupled with DMPP application to compare the biological inhibition of sorghum to an artificial inhibitor. Nitrogen and potassium fertilizers were applied in a manner similar to local practices, with DMPP application occurring concurrently. Plants were grown throughout the summer and harvested in early October for the 2021 and 2022 growing seasons to represent a typical corn system in Massachusetts.

The methodology of this work relies primarily on the capture and analysis of N2O gas leaving the soil, which represents a loss of nitrogen from the system as well as a problematic source of greenhouse gas emissions. To capture this gas flux, we implemented static chambers placed over the soil for a period of 30 minutes and sampled gas from the chamber every 15 minutes. Gas samples were loaded into pre-evacuated glass vials and analyzed through gas chromatography. To ascertain the temporal variability of N2O flux, these measurements were carried out throughout the New England summer every 2 or 3 days. This sampling scheme is more intensive than those typically employed in the literature, with many studies measuring gas flux on a weekly basis or longer gaps. The high frequency of sampling events allowed us to better account for stochastic variables in the system such as soil moisture and temperature fluctuations as they changed throughout the season.

In addition to gas flux, we collected data on soil temperature and moisture, as well as detailed atmospheric data from a nearby weather station at the research farm. At the end of the growing season, we collected above ground biomass from representative areas of each plot to measure bulk yield for silage production, the intended production outcome for this experiment.

To further understand the underlying mechanisms of the reduction in N2O flux we periodically and destructively took bulk soil and root samples for microbial community analysis. In this analysis we compared the abundance of microbial communities responsible for nitrogen transformations in the soil, mainly ammonia-oxidizing bacteria and archaea as well as denitrifying bacteria. We will also be coupling these comparisons to more broad observations of the microbial community structure at high resolution to get insights into how the wider microbial community responds to N2O reduction treatments and intercropping systems.

The need to feed the ever-growing human population while decreasing greenhouse gas emissions from large-scale agriculture remains a global problem of paramount importance. One major source of these emissions is through nitrous oxide (N2O) production, a greenhouse gas with a warming potential nearly 300 times that of CO2. This potent greenhouse gas is formed through the action of soil microbes when they compete for artificial nitrogen fertilizer. While there are synthetic inhibitors that reduce N2O emissions, there can be many off-target effects. A promising alternative to these inhibitors is leveraging the natural ability of some plants to antagonize the microbial production of N2O, termed Biological Nitrification Inhibition (BNI). This ongoing research utilizes the BNI capacity of Sorghum bicolor, a staple grain crop in Africa and Southern Asia intercropped with corn (Zea mays). Plants were grown as monocrops or intercrops with alternating row and mixed seeding at the UMass Crop and Animal Research and Education Farm in South Deerfield, MA. These cropping treatments were repeated with an artificial nitrification inhibitor, DMPP, for comparison. Throughout the growth season, soil gas flux samples were collected via chambers covering the soil and analyzed through gas chromatography. Measured N2O concentrations over time were then converted to overall flux (production and consumption) to determine the reduction in N2O emissions. In addition to gas measurements, soil and roots were destructively sampled periodically throughout the growth season. Community analysis of the bulk soil and rhizosphere will reveal the microbial community’s response to the different cropping systems or the synthetic inhibitor treatment at high levels of resolution. At the end of the field season, plants were harvested to determine overall yield for all treatment groups. This experimental design has been repeated for a second year to account for seasonal variations in weather patterns. Throughout both years of the field trial, we found nearly 20% fewer N20 emissions in the sorghum monocrop plots as well as with mixed seed intercropping with the addition of DMPP, compared to the corn monocrop control. Total plant biomass production was not influenced by either treatment variation.

        The core hypothesis of this work is that the BNI capacity of sorghum will result in more nitrogen fertilizer available for both corn and sorghum when planted in close proximity, as well as reduced N2O emissions. The inhibitory chemicals secreted from the sorghum roots will affect the root zone of corn when planted in a way that both root systems overlap. This effect will lead to more plant-available nitrogen, lower N2O emissions, and higher silage yields for both corn and sorghum in intercropped systems. We expect this effect to be most pronounced in the mixed seeding plots as those plants are grown in the closest proximity. This work will determine the efficacy of intercropping corn, a plant with heavy nitrogen fertilizer needs with sorghum, a plant which has evolved ways to better compete with soil microbes for the available nitrogen applied as fertilizer, compared to the commercial inhibitor DMPP. To better understand the role of soil biological processes in controlling plant available nitrogen, a subsequent, complimentary experiment will be carried out this year to uncover the mechanism of action of the sorghum inhibition. These experiments together investigate a promising alternative to the current synthetic inhibitors in an effort to reduce greenhouse gas emissions in large-scale agriculture, while simultaneously reducing the amounts of artificial nitrogen fertilizer required to grow corn in today’s agriculture. Both resulting effects, the increased nitrogen fertilizer availability and reduced N2O production, will directly support the chosen objective, and widen our understanding of soil health and resilience. Resilience of this agricultural system is further supported by the documented drought resistance of sorghum, which will be needed with the expected longer drought periods in the currently changing climate. These changes will directly affect farmers who produce crops for silage.

Cranberry production has a long history in Massachusetts (MA) that adds important economic and aesthetic value to the region.  About 30% of US acreage and the two largest cranberry handler companies are located in Massachusetts. Threats to the sustainability of cranberry production in MA and elsewhere in the US come from many sources: consumer demands for sustainable but inexpensive products, commodity pricing in an industry that is currently over-supplied with juice concentrate, changes to industry (handler) fruit quality standards, rising costs for energy and pest management products, climate change, and changing standards in pesticide use to accommodate global marketing. 

The majority of cranberry acreage in MA is still under old cultivars with low productivity and poor disease resistance and MA does not have a breeding program for new cultivars. Growers in MA are interested in bringing in new hybrid cultivars from breeding programs in New Jersey and Wisconsin. However, without proper cultivar evaluation under MA growing conditions, growers are hesitant to do so because of the significant financial risk.  This project will evaluate new hybrid cultivars under MA growing conditions and provide growers with reliable data to use in decision making when considering bog renovation.

In Massachusetts, several invasive insect species are either already affecting or pose a serious threat to the specialty crop industry. Stakeholders have voiced the need to address the most destructive invasive insects threatening their crops. In recent years, there has been interest in reduced-risk materials with insecticidal properties for the invasive pest spotted wing Drosophila (SWD), a vinegar fly that attacks berries and other soft-skinned fruits such as peach and cherry. Of particular interest are low-cost materials that could be used as attractants in traps or as insecticidal food-based baits, as opposed to broad-spectrum insecticides applied to the foliage against some pests. In this project, we will determine whether materials that are commonly available in households can be used to attract adult SWD to traps. Efforts will be made to develop an inexpensive insecticidal bait. The response of female codling moth and Oriental fruit moth, two important pests of apple, pear, and related crops, to lures that are based on plant material will be quantified under laboratory and field conditions. Our ultimate goal is to develop a food bait for SWD that is inexpensive and effective. This project also seeks to improve the effectiveness of monitoring systems for codling moth and Oriental fruit moth. If successful, results may lead to the development of more effective monitoring systems for these two moth pest species.

This proposal describes a next-generation sequencing (NGS)-based approach to identify genes that control unisexual flower development in Zea mays (maize). Maize develops separate male flowers in the tassel and female flowers in the ear (Klein etal., 2018). The development of unisexual flowers is important for hybrid crop production - separate tassel and ear flowers allow humans to very easily make controlled crosses (Phillips, 2010).  Many cereal crops related to maize, like rice and wheat, have unisexual flowers, hampering hybrid seed production (Kellogg, 2015). In addition, the same process that leads to the development of maize flowers in the tassel - carpel suppression - also occurs in half of all ear flowers, effectively halving the number of seeds a maize ear could produce (Cheng et al., 1983).  Thus, modifying the genes that control carpel suppression using CRISPR/Cas9 genome engineering could allow crop engineers to generate unisexual flowers in other grass crops, and to improve yield in maize (Gao, 2018).

Tree-fruit growers must adopt economically and environmentally sustainable orchard management strategies to remain competitive in regional, national, and international markets; to meet consumer demand for high quality fruit; to address the pressure to reduce chemical use; and to enhance production efficiency. The root system is a key orchard component that can impact these issues, and tree fruit growers address these issues by utilizing the genetic traits of rootstocks, onto which the fruiting varieties are grafted. Rootstocks can provide a range of tree vigor control and final tree size when matched to optimize local soil and climatic conditions, allowing for higher density plantings with smaller trees that are more efficient per unit of land area. Higher density plantings facilitate earlier production and greater cumulative yield potentials, but also must provide appropriate vigor for the site so that canopy shade and pruning do not become excessive. To be profitable, growers must establish high-density orchards with appropriate rootstocks grafted to cultivars that are in demand by consumers and have high market value. However, establishment costs for high-density orchards are 10 to 20 times more per land area than lower-density plantings, thus greatly increasing economic risk. Grafting to a rootstock inappropriate for the regional climate or orchard soil type can be economically disastrous. Potential economic returns from high-density orchards can far exceed that of low-density orchards, particularly during the first 10 years. Past NC-140 research successfully identified reliable size-controlling, early-bearing rootstocks for apple and cherry, and has led to the integration of their use in high-density production systems to reduce tree size, labor costs and significant tree and/or production losses from disease and environmental stresses. Size-controlling rootstocks for peaches, pears, apricots, and plums are now in their relatively early stages of development, concomitant with potentially major changes in tree training as they are integrated into more efficient and productive orchard systems.

The project will employ established field and laboratory methods to measure litter decomposition, soil organic matter turnover, and nitrogen transformations. These methods could include isotope labeling and recovery, litter decomposition, quantifying soil organic matter, gross nitrification and nitrogen mineralization, potential net nitrification and net nitrogen mineralization, nitrous oxide production, carbon mineralization, and quantifying microbial biomass. These measurements are often collected from both field equipment and laboratory microcosms. The results are analyzed using a variety of tools. Generally, graphing tools are first used to examine trends in the data. The data will then be statistically analyzed using linear mixed models and, potentially, model selection. The statistical output is combined with graphic trends and site background information to interpret data and produce study outcomes. This study will incorporate formal education programs. The research project will be the basis from which to train a graduate student on methods in soil biogeochemistry and incorporation of applied research into graduate study. The field sites and methods will be incorporated into formal laboratory instruction for undergraduates. Involving undergraduates provides both inclusion in primary research and evidence of how research outcomes can be incorporated by farmers. 

This research, to be conducted at the University of Massachusetts, Amherst Crop and Animal Research and Education Farm in South Deerfield, MA.  In September of the first project year, white clover will be established. The effectiveness of four clover suppressing methods prior to corn planting will be investigated. Two full plot treatments, mowing and chemical control, and two in-row treatments, shank till (ST) and zone till (ZT), will be combined to form the four treatments: mowing + ST, mowing + ZT, chemical + ST, and chemical + ZT. The ST treatment, also called strip till, will create a 30 cm band to 5 cm depth while the ZT treatments will use a rotary implement to create a 40 cm band at 8 cm depth. The shallow tilling depths terminate the in row kura clover biomass without disrupting the larger soil structure. The plots with the mowing treatment will be mowed across the entirety of the plot the week before planting to suppress the clover biomass prior to planting. The mowing treatments will again be mowed between rows at mid-season to reduce clover height and prevent encroachment into the row. The chemical treatments will be sprayed as a broadcast application of glyphosate at the same time as the mowing treatments at a rate of 2.3 L ha-1. The chemical treatment will again be sprayed between rows mid-season to reduce clover height and prevent encroachment into the row. The day before planting, the tilling treatments will be applied to the planting row.

In the late spring of the first project year, we will delineate 16 main plots across the field of clover. Experimental plots are 24 m long × 2.4 m wide. The width of the plots allows for planting three rows of corn. Each plot will be randomly assigned a treatment (four treatments replicated four times). To test the N benefit of clover for corn production, the main plots will be divided into four subplots (6 m. long) for each of four nitrogen fertilizer treatments resulting in 64 total plots. The four nitrogen fertilizer treatments are 180 kg N/ha, 120 kg N/ha, 60 kg N/ha, and 0 kg. N. The fertilizer is applied in two stages: one-third of the application rate as starter fertilizer and two-thirds as side dressing when the corn is approximately 12” tall (V6 growth stage). The zero-fertilizer treatment allows us to measure both nitrogen use efficiency as well as the N benefit from only the clover. We will also establish a plot of conventionally grown silage corn (50 m. × 5 m.) adjacent to the treatment plots which will serve as a comparison for all above- and below-ground measurements under living mulch. In year 2, the 64 plots will receive the same treatment along the same timeline as year 1.

Measurements:

Plant: Clover biomass in November (for fall grazing) and Late April (spring grazing), corn yield and quality, and Late April (spring grazing), corn yield and quality, including RFV and Milk Value.

Soil: leaching, N residues, N2) and Co2 emission

Fusarium oxysporum species complex (FOSC) can cause vascular wilt on over 100 cultivated plant species (Ma et al., 2013; Michielse & Rep, 2009; Pietro et al., 2003). Because of its significance, F. oxysporum is listed among the top 10 fungal pathogens by the journal “Molecular Plant Pathology” (Dean et al., 2012). In the New England region, wilt diseases caused by Fusarium oxysporum are common agricultural problems that affect the production of vegetables, including asparagus, tomatoes, eggplant production, ornamentals, and variety of flowers (Elmer & Marra, 2011;https://www.prevalentfungi.org/). The widespread resistance to existing fungicides and the persistence of the thick-walled fungal chlamydospores in the soil heightens the difficulty in controlling the diseases and emphasizes the importance of appropriate control measures.

Sheep are valuable livestock species that have been raised for their production of meat, milk, fleece, and other by-products. More importantly, given their anatomic and physiologic similarities to humans, genetically modified sheep have become an important human disease model in pharmaceutical and biomedical research. Compared with somatic cell nuclear transfer and random transgenesis, CRISPR/Cas9-mediated genome editing is highly efficient and precise. However, due to the impaired developmental competence of embryos cultured in vitro, the overall success rate is still low when blastocyst embryos are transferred into the recipients. In this study, we propose to optimize the microenvironment of in vitro cultured sheep embryos by modulating the culture matrix stiffness, fluid flow, and embryo rolling, to improve the developmental competence of blastocysts, which stage allows for a much faster and less-painful non-surgical embryo transfer than the surgical procedure. Our proposed research, if successful, will innovatively streamline the production of genetically modified sheep and other large livestock animals, to increase both human and animal health and welfare.

As an important group of crops, legumes are prized for their high protein content, which is thanks to their remarkable ability to make their own nitrogen nutrient through a symbiotic relationship with a particular group of bacteria. We still do not fully understand the legume genes that allow these plants, but not most others, to enter this nitrogen-fixing symbiosis. Evolution through millions of years has turned this relationship into a very elaborate process, requiring hundreds if not thousands of genes from both partners. To speed up the rate of scientific discovery, we developed a genetic method based on the CRISPR/Cas9 technology to examine genes suspected to be involved in this mutualistic interaction. This approach will allow us not only to study one gene at a time, but multiple genes at once if necessary. We will carry out the research on a small legume species easy to manipulate in the laboratory, but the findings will have important implications for important crops, such as soybeans, peas, and peanuts.

Brucella spp. are Gram-negative bacteria that infect animals and humans. B. abortus, B. melitensis, and B. suis are major pathogens of cattle, goats and sheep, and swine, respectively. Brucella infections in these food animals have significant economic impacts in areas of the world where they are not controlled by effective eradication programs. In their main animal hosts, brucellosis causes spontaneous abortion or birth of weak offspring, reduced milk production and infertility. Transmission occurs by direct contact with infected blood, placentas, fetuses and consumption of raw animal products, especially milk and milk products (Nicoletti 1989). Understanding the physiology of these bacteria and how host infection is modulated is therefore important for control of these pathogens.

Bacteria manage changes to their environment, such as the stress of host infection, by altering the levels of RNA, protein and signaling molecules to cope with these changes. Proteases play central roles in bacterial physiology. They modulate the activity of cellular proteins and remove damaged proteins from cells. Because proteolysis is irreversible the catalytic function of cellular proteases must be tightly regulated. While the extent and capacity of proteolytic control in Brucella is unknown, modern proteomic strategies have now made it possible to capture this important facet of bacterial regulation.

In this proposal we aim to chart the dynamic proteome in Brucella abortus, identify the roles of specific regulators in controlling these dynamics, and share these results with the scientific community by making a searchable open-access databases. We believe that this atlas will provide a starting point for all those studying Brucella to either identify new candidates of interest or to validate regulatory mechanisms for targets under study. Given the economic and agriculture impact of brucellosis on animal hosts, we predict that this insight will spur understanding of how to manage Brucella infections and reduce the economic burden of this disease.

In this work we seek to evaluate the role and interactive effects of stressors on the health of pollinator communities. One salient abiotic stressor is climate change. To evaluate one potential impact of climate change on Apis and non-Apis bees, we will expose pollinator dependent plants to heat-wave conditions compared to control temperatures in warming chambers prior to bloom (heat wave is defined here as 3 days with temperature 98th percentile for Massachusetts in July). After exposure to the heatwave or control temperature conditions, the plants will be deployed in the field in bee communities that include both Apis and non-Apis bees. We will evaluate visitation rates, foraging patterns, and pollination effectiveness (as measured by final fruit set and fruit weight) by the different bee taxa using paired bagged vs unbagged flowers. This design expands our understanding of a key abiotic stressor impacting bee communities.

Regeneration is the future of Massachusetts forests. It is critical for the conservation of the State's forestlands and for the continued provisioning of the myriad ecosystem services they provide (sustainable timber and wood products, carbon storage,wildlife habitat, clean drinking water, biodiversity, recreational opportunity, and aesthetic/intrinsic value). Global change related factors including novel climatic conditions, invasive plants, deer overpopulation, and habitat fragmentation threaten current and future forest regeneration within Massachusetts. These threats come at a critical time when we are already observing increased mortality of economically and ecologically important tree species across the State at the hands of non-native pests and pathogens. Ensuring successful regeneration of desired tree species and natural communities within these damaged forests is paramount to the continued health, vigor, and viability of the State's forest resources.Adaptive forest management may be used to overcome contemporary regeneration challenges, ensuring the conservation of healthy and valuable forest ecosystems. However, we currently lack sufficient regeneration data and scientific understanding of the various factors impacting regeneration to develop and test meaningful adaptive management strategies.

Forest dynamics and the spatial and temporal modeling of the dynamics of Food-Energy-Water (FEW) systems at a watershed scale are critical for sustainable land and resource management. The assessment of vegetation (Forest and plant biomass) and land use dynamics is vital for scientific innovation and for enhancing local and regional sustainability and resilience. Assessing built, natural, and social components and their interactions as a dynamic system can lead to comprehensive strategies that improve food production, conservation, energy efficiency, and water resources. Dynamic changes in FEW systems are complex processes, especially the state of the complex system and its trajectory over time. As the population increases and new demands on ecosystem services, watersheds face environmental, energy, and food challenges. This could include polluted waterways, floods, droughts, loss of forest and green space, energy inefficiencies, crop loss, yield loss, soil erosion, increasing density of built structures, and a deterioration in watershed services. Increasing population densities increase built components causing higher forest loss, impervious cover, wastewater discharges, stormwater surges, nonpoint source pollution, loss of open space, farmland loss, and habitat fragmentation that substantially impact watershed systems. Agricultural land is also at increasing risk from urbanization with pressure to produce more in a limited area and with limited resources.

The nexus between food, energy, and water (FEW) has strong interaction with land use-based assessment, requiring system-based modeling for policy. The system information on interactions, tradeoffs, trajectories, thresholds, and endpoints in FEW systems is needed to evaluate sustainable patterns and processes that can be used to manage built, natural, socioeconomic, and cyber systems. We propose to study these issues at a regional watershed scale through integrated spatial and temporal modeling of forest dynamics at a watershed scale. 

The goal of this research is to simulate and optimize interactions in patterns and processes in built, natural, and socioeconomic components and forest dynamics on FEW services based on a multiscale system at the watershed scale. Specifically, (i) to evaluate baseline spatial and temporal changes in FEW systems at the watershed scale; (ii) To assess the influence of changing built and natural environment on FEW dynamics and processes; (iii) to evaluate farmland management and its impacts on FEW systems; (iv) to study attitude, values, and behavior towards FEW outcomes under land-use patterns and conservation alternatives; (v) to develop a multiattribute, optimization model for pattern and BMP choice to enhance watershed sustainability for FEW provision; (vi) to develop a web-based decision support system (WDSS) with site-specific information for stakeholders on FEW resilience and conservation choices.

The target audience will include farmers, land owners, municipal officials, private forest owners, government agents, nonprofits, educators, scientists, and professionals. The information generated will cover the watershed-based assessment, strategies to sustain water resources through forest management, handling increasing urban demands through forest BMPs, supply augmentation potential through forest ecosystem functions, and potential effects of LID at the watershed scale. Educators can use the information to develop simple classroom activities demonstrating workshop concepts. 

Research activities in the Connecticut River Watershed with result in outcomes that directly benefit the target audience through capacity building and spatial information that will be helpful for decision-making. The workshops will provide information on the spatial distribution of water supplies and use and trends in distribution. The workshop will recommend strategies to sustain water resources and will involve brainstorming and breakout sessions to develop implementation plans. A website will be developed for the project and will be used to disseminate information to communities within the watershed and watersheds throughout the region and the US

Increasing environmental stresses make crops ever more succeptible to the impact of plant viruses. Plant viruses affect plant functioning and, specifically, the root system. For example, virus infected cover crops may hamper root growth and activity. This may influence the effect of cover crops on the cycling of carbon and other nutrients in soils. Consequently, virus infections may undermine the beneficial use of cover crops to improve soil health, with unclear consequences for soil carbon storage, greenhouse gas emissions, and nutrient status. This project therefore tests how plant virus infection influences the impact of cover crops on soil carbon and nutrient cycling.

Objective 1: To build a godwit stopover map, we will use a surface water detection algorithm developed for wetland environments (Dynamic Surface Water Extent, or ‘DSWE’) on integrated Landsat-8 and -9 and Sentinel-2 surface reflectance data layers to roughly approximate the location and shape of all surface water along our roadside transects. We aggregate all connected water pixels observed during April and May into feature polygons, then overlay each water feature with suitability observations from our roadside surveys.

Objective 2: To investigate the associations between the occurrence of wetlands suitable for godwits, climate, and land-use, we will inspect the scaled variable importance and partial dependence plots of environmental indices in our random forest model. We will also verify the importance of each variable separately by comparing the prediction made from our full model to the prediction of a similar model with the respective variable randomized.

Objective 3: To identify the optimal network configuration of seasonal wetlands to support godwit migration, we take the results from Objectives 1 and 2 to determine the location and number of wetland sites in the study area that are suitable for godwits and other wetland-dependent migratory shorebirds. Then, to determine the number of stopover sites necessary to support migratory godwits in the region, we will apply network theory and centrality metrics to all sites identified in our stopover network map. Following Donnelly et al. (2021), we will evaluate four metrics for each site/node: its connectedness, betweenness, degree, and resistance. To evaluate the effects of potential future changes to this network, we will conduct incremental node removal experiments. First, we will evaluate a fifth metric — the integral index of connectivity — for each node before and after removal, and calculate their relative difference. Finally, we will use simulations of incremental random node removal to determine the median number of losses that will fragment the stopover network.

Objective 4: To assess the vulnerability of godwits to future climatic and land-use changes, we will use a generalized linear model to estimate the effects of precipitation, temperature, and agricultural practices on the total number of suitable stopover sites in the study area. For this, we generate maps of stopover sites from 2013-2023. We then extract total precipitation, as well as daily high and low temperatures over the study area from the ERA-5 reanalysis weather dataset. Finally, we extract corresponding crop cover acreage and total drain tiling acreage statistics for each year.

Objective 5: To develop a Shorebird Action Plan we will partner with the conservation organization, The Nature Conservancy. With their help, we will host a series of workshops that bring together land managers, landowners, and conservation practitioners to identify potential future actions to conserve shallow water wetlands in agricultural landscapes. In 2023 we will begin with three counties in which our previous work has indicated high concentrations of temporary-seasonal wetlands, as well as the presence of landowners interested in becoming involved in on-the-ground conservation actions. Then, in 2024, we will expand to 12 additional counties across the two states and include a broad array of participants representing a diverse cross-section of the stakeholder community. These workshops will focus on: 1) documenting the constraints faced by farmers, 2) generating potential actions that could facilitate seasonal wetland conservation while simultaneously benefiting farmers and other landowners, 3) synthesizing possible conservation actions that could provide shallow water wetland habitat to migratory shorebirds, 4) identifying existing or new incentive programs and strategies to scale the implementation of key conservation actions, and 5) deriving key principles for use in guiding future conservation effort