Browsing by Author "Day, Susan D."

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    An Assessment of the Potential Impacts of Emerald Ash Borer (Agrilus planipennis Fairmaire) on Virginia's Municipal Street Trees
    Wright, Gordon Tyler (Virginia Tech, 2011-07-22)
    Emerald ash borer (Agrilus planipennis Fairmaire) (EAB) is an invasive, wood-boring beetle (Coleoptera: Buprestidae) introduced unintentionally to the United States from East Asia that infests and eventually kills native ash trees (Fraxinus spp.). First detected near Detroit, Michigan in 2002, EAB had spread to fifteen U.S. states by 2011, killing an estimated 50 million ash trees along the way. EAB was first discovered in Virginia in 2003 and re-infested the state in 2008, raising concerns over impacts that the invasive pest might have on municipal urban forests and street trees. Despite these concerns, little is known about native ash abundance in Virginia's urban forests; as a result, potential EAB impacts have been difficult to project. In this study, street tree assessments were conducted in fourteen Virginia municipalities using i-Tree Streets®, which is a software program developed by the U.S. Forest Service that uses field inventory data to estimate street tree abundance and composition along with the quantity and monetary worth of functional benefits provided by these street trees. In addition to estimating potential losses of functional benefits provided by native ash street trees, information obtained from Virginia Dept. of Transportation was used to estimate the potential cost of removing these trees from the street side. The assessment indicated that there are about 4,600 native ash street trees in the fourteen studied localities and that native ash species comprise about 2% of municipal street tree populations on average. The highest relative abundance of native ash was found in Winchester City (5.8% of all street trees) whereas Richmond City had the greatest number of native ash street trees (estimated at 1,417). In terms of species importance (which accounts for both the relative abundance and relative size of trees in the population), only two localities (City of Roanoke and Town of Abingdon) had a native Fraxinus species among the top-five most important street tree species in the locality. In contrast, every municipality had at least one Acer species among the top-five, and eight of fourteen localities had at least one top-five Quercus species. Native ash street trees in the studied localities were estimated to provide functional benefits (energy conservation, stormwater mitigation, air pollution abatement, carbon sequestration, and aesthetic contributions) valued at over $535,000 annually, or roughly $38,000 per locality. In addition, carbon stored in these trees (about 17 million kilograms) was valued at nearly $277 thousand. The total estimated cost of removing lost ash trees was estimated at nearly $1.75 million, averaging about $124,000 for each municipality, and replacing the canopy cover and basal area provided by existing native ash street trees would exceed $17 million. In total, the studied localities would incur a gross financial impact of about $20.26 million due to losses of functional benefits and structural assets provided by native ash street trees.
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    Biochar in Land Reclamation, Biosolids Applications and Prescribed Fires
    Fields-Johnson, Christopher Warren (Virginia Tech, 2016-12-01)
    Biochar is a form of stable organic carbon whose application to soils has the potential to sequester large amounts of atmospheric CO2 while improving the physical, chemical and biological properties of soil. However, the optimal rates and methods of biochar application are unknown for many situations. Three experiments were performed to test methods of biochar application to soils as a stand-alone amendment, in combination with biosolids as a complementary amendment and in-situ through controlled landscape burning. The first was a greenhouse pot study, which involved combining biochar with spoil from an Appalachian surface coal mine to grow trees. Biochar combined with mine soil produced a much higher growth rate for trees, and pure biochar helped tree root growth, suggesting that it might be useful as a broadcasted amendment, as a nursery growing medium or as a backfill in tree planting holes. The second experiment explored methods to combine biochar and biosolids materials to form a granular product. Combining biochar and biosolids before applications reduced windborne losses of biochar as well as the nutrient leachate produced by the biosolids. Drum rolling was found to work best for producing aggregate granules. Wetting pure biochar to 100% gravimetric water content before applications reduced windborne losses from over 50% to under 5% as compared to when it was applied as a dry product. A series of controlled burns were conducted in the third experiment to determine the ideal range of meteorological conditions to produce the highest possible biochar yields in-situ. Relative humidity, forest litter moisture and ambient temperature were found to be the governing factors over the tonnage of biochar produced. Up to 3.0 Mg Ha-1 of biochar were produced under ideal conditions by controlled burning. Repeated high-yielding burns have the potential accumulate large amounts of biochar in the soil to improve soil properties.
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    Conservation Programs and White-tailed Deer Ecology
    Royeen, David D. (Virginia Tech, 2019-05-07)
    White-tailed deer have reached historical numbers since nearly being wiped out due to overhunting and habitat loss. This paper seeks to review the rebound of white-tailed deer populations, specifically analyzing the role conservation practice and habitat management have played. A brief history of private land contracts in the United States is established before relating deer ecology to habitat availability. The importance of deer from the perspective of humans as well as the ecosystem is highlighted in an effort to encourage and promote conservation and habitat preservation efforts. This work seeks to answer the question “How do conservation programs influence white-tailed deer behavior and what steps can land managers take to protect wildlife on their property?”. A list of recommendations for land owners is given to share best-practice policies for governing a healthy population of white-tailed deer. Lastly, study limitations and constraints of this paper are analyzed to promote transparency and identify areas of concern with data collection.
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    Designing an Urban Forest Inventory System for a Small Municipality: A Case Study of Falls Church, Virginia
    Walker, Catriona (Virginia Tech, 2015-05-16)
    The City of Falls Church, Virginia is an independent city in the Washington, DC metropolitan area, with a population of 13,600 within its two square mile jurisdiction. The City's residents are justifiably proud of their beautiful and extensive urban forest. Falls Church has been a Tree City USA for thirty-six years, longer than any other community in Virginia, and the protection of its mature trees and expansion of its tree canopy are key goals in the City's Comprehensive Plan. This report describes the development and testing of a tree inventory system for the City using the ESRI ArcGIS data mapping platform. The database design and the procedures for data collection are described and illustrated. Strengths and limitations of the ESRI software and hardware options for the purpose of collecting and displaying tree inventory data are considered, and recommendations are made for further development of the inventory system. It is hoped that this case study will be of use to other entities considering the creation of a complete or partial tree inventory.
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    Development of Urban Tree Growth Models Based on Site and Soil Characteristics
    Wenzel-Bartens, Julia (Virginia Tech, 2010-11-04)
    Trees provide numerous benefits crucial to urban environments, yet poor growing conditions often prevent trees from reaching their genetic potential for growth, longevity, and ecosystem function. To overcome these limitations, greater understanding of tree growth in the urban environment is needed. The goal of this research project was therefore to characterize a broad suite of soil characteristics associated with urban tree plantings and evaluate their suitability for modeling physical dimensions and growth rates of urban trees. A series of observational studies and experiments was conducted on urban soils inhabited by two tree species (Zelkova serrata (Thunb.) Mikano and Quercus phellos L.) in Washington, DC and one tree species (Quercus virginiana Mill.) in Jacksonville, FL – two major metropolitan areas of the eastern United States with contrasting climate and soils. Characterization of urban soil attributes within cities revealed low variability for some properties (soil texture, pH, and certain plant nutrients with coefficients of variation (CV) below 0.5), but high variability (CV>1.0) for others (nitrate, ammonium, copper, and zinc). This is dependent on the location. These findings suggest that tree planting site evaluations may not require measurements for all soil properties and that representative sampling may be sufficient to accurately characterize most soil properties within a city. Field assessment of urban tree soils also revealed that conventional measures of soil compaction are difficult to obtain due to obstructions by roots and other foreign objects. To address the critical need for efficient and reliable assessment of soil compaction around urban trees, an experiment was conducted to develop bulk density estimation models for four common soil texture classes using soil strength and soil moisture as predictor variables. These models provided medium (0.42) to high (0.85) coefficients of determination when volumetric water content (VWC) was log transformed, demonstrating that measurements of soil texture, strength, and moisture can provide rapid, reliable assessment of soil compaction. Tree growth modeling focused on three response variables: canopy projection (CP), canopy volume (CV), and peak-increment-area age (PIA). To calculate PIA, tree-ring analysis was used to determine the age at which maximal trunk diameter growth occurred between transplanting and time of sampling. Because Q. virginiana has difficult-to-distinguish growth rings, an intensive tree-ring analysis of cores collected from these trees was conducted. The analysis revealed interseries correlation coefficients of up to 0.66, demonstrating that Q. virginiana can be aged with fairly high confidence in an urban setting. Empirical models developed for all three tree species using the suite of soil and site variables explained 25% – 83% of the observed variability in tree physical dimensions and growth rates. Soil pH was found to be a significant predictor variable for the majority of growth models along with nutrients such as Fe, B, Mn, and Zn, which are also associated with soil alkalinity. Models for PIA possessed the highest coefficient of determination, suggesting that measurements of soil conditions can be used confidently to predict the age at which growth rate subsides in these species. CV and CP were not predicted as well by soil-related variables, presumably because above-ground constraints such as pruning and building encroachment can affect canopy size without necessarily affecting growth rate. Certain prediction models for all three species included predictor variables with counterintuitive influences on tree growth (e.g., negative influences of soil depth on Q. phellos and soil volume on Q. virginiana), suggesting that either these urban trees are responding to these variables in a novel manner or that variables unaccounted for in these models (perhaps related to urbanization or high vehicular traffic) are concomitantly influencing tree growth.
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    Earthworms in the Urban Environment: Can Population Augmentation Improve Urban Soil Properties?
    Gift, Danielle Marie (Virginia Tech, 2009-07-17)
    Urban forests perform essential ecological functions, and their performance is dependent on soil quality, which is often degraded by human activity. Because earthworms play a key role in soil health, augmenting earthworm populations in urban soils may improve tree performance. However, we know very little about earthworm ecology in highly urbanized soils. The objectives of our study were: (1) to assess earthworm demographics across a range of urban land uses and (2) to evaluate earthworm augmentation techniques for rehabilitating disturbed soils and improving tree growth. 1. We conducted an observational study across three landuse types to assess earthworm abundance and diversity as well as associated soil properties. Earthworm abundance and biomass in were affected by land use type, disturbance time frame, and seasonality. Earthworm abundance and biomass were affected by a suite of complex soil and temporal variables, and soil temperature and moisture seemed to be the most influential properties. 2. We conducted an earthworm inoculation experiment on a compacted cut-fill field soil with a very low existing earthworm population. In 2008, three soil treatments (control, compost, and compost + earthworm) were applied to 2 m2 plots into which two common urban tree species with contrasting soil tolerances were planted (Acer rubrum and Cornus florida). We measured soil physical and chemical properties along with earthworm survival and soil respiration. Earthworm inoculation did not succeed in improving bulk density or increasing soil organic matter, yet it was successful in increasing soil CEC, Fe, and Mn relative to compost only effects.
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    Floating wetlands for urban stormwater treatment
    Wang, Chih-Yu (Virginia Tech, 2013-11-12)
    A floating treatment wetland (FTW) is an ecological approach which seeks to reduce point and nonpoint source pollution by installing substrate rooted plants grown on floating mats in open waters. While relatively novel, FTW use is increasing. A review of literature identified several research gaps, including: (1) assessments of the treatment performance of FTWs; (2) evaluations of FTWs in the U.S., particularly within wet ponds that receive urban runoff; and (3) plant temporal nutrient distribution, plant growth rate, and the long-term persistence of the FTWs in temperate regions with periodic ice encasement. An assessment model, i-FTW model, was developed, and its parameter s fitted based on data from 14 published FTW studies in the first research topic. The estimated median FTW apparent uptake velocity with 95% confidence interval were 0.048 (0.018 - 0.059) and 0.027 (0.016 - 0.040) m/day for total phosphorus (TP) and total nitrogen (TN), respectively. The i-FTW model provided a more accurate prediction in nutrient removal than two common performance metrics: removal rate (mg/m2/day) and removal efficiency (%). In the second research topic, the results of a mesocosm experiment indicated that FTWs with 61% coverage, planted with pickerelweed (Pontederia cordata L.) or softstem bulrush (Schoenoplectus tabernaemontani), significantly improved TP and TN removal efficiency of the control treatment by 8.2% and 18.2%, respectively. The pickerelweed exhibited significantly higher phosphorus and nitrogen removal than the softstem bulrush when water temperatures were greater than 25 deg C. Field observations in the third research topic found that pickerelweed demonstrated higher phosphorus removal performance (7.58 mg/plant) than softstem bulrush (1.62 mg/plant). Based on the observed seasonal changes in phosphorus distribution, harvest of above-ground vegetation is recommended to be conducted twice a year in June and September. Planted perennial macrophytes successfully adapted to stresses of the low dissolved oxygen (DO) concentrations (minimum: 1.2 mg/L), ice encasement, and relatively low nutrient concentrations in the water (median: 0.15 mg/L TP and 1.15 mg/L TN). Systematic observation of wildlife activities indicated eight classes of organisms inhabiting, foraging, breeding, nursing, or resting in the FTWs. Recommendations for FTW design and suggestions for further research are made based upon these findings.
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    Future Global Soil Respiration Rates Will Swell Despite Regional Decreases in Temperature Sensitivity Caused by Rising Temperature
    Jian, Jinshi; Steele, Meredith K.; Day, Susan D.; Thomas, R. Quinn (American Geophysical Union, 2018)
    Between 1960 and 2014, the global soil respiration (RSG) flux increased at a rate of 0.05 Pg C year⁻¹; however, future increase is uncertain due to variations in projected temperature and regional heterogeneity. Regional differences in the sensitivity of soil respiration (RS) to temperature may alter the overall increase in rates of RS because the RS rates of some regions may decelerate while others continue to rise. Using monthly global RS data, we modeled the relationship between RS and temperature for the globe and eight climate regions and estimated RSG between 1961 and 2100 using historical (1961–2014) and future (2015–2100) temperature data [Representative Concentration Pathways (RCP2.6 and RCP8.5)]. Importantly, our approach allowed for estimation of regional sensitivity, where respiration rates may peak or decline as temperature rises. Estimated historical RSG increase (0.05 Pg C year⁻¹) was similar to the RSG increase of previous estimates. However, under the RCP8.5 scenario, which estimates approximately 3 °C of warming globally, the forecasted acceleration of RSG increased to an average of 0.12 Pg C year⁻¹. Under RCP8.5, the temperature sensitivity of RS declined in the arid, winter-dry temperate, and tropic. These regional declines were offset by increased RS sensitivity and fluxes from the boreal and polar regions. In contrast, under RCP2.6 RSG decelerated slightly from current rates. If rising greenhouse gas emission remains unmitigated, future increases in RSG will be much faster than current and historical rates, thereby possibly enhancing future losses of soil carbon and contributing to positive feedback loops of climate change.
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    Global soil respiration: interaction with macroscale environmental variables and response to climate change
    Jian, Jinshi (Virginia Tech, 2018-02-05)
    The response of global soil respiration (Rs) to climate change determines how long the land can continue acting as a carbon sink in the future. This dissertation research identifies how temporal and spatial variation in environmental factors affects global scale Rs modeling and predictions of future Rs under global warming. Chapter 1 describes the recommend time range for measuring Rs across differing climates, biomes, and seasons and found that the best time for measuring the daily mean Rs is 10:00 am in almost all climates and biomes. Chapter 2 describes commonly used surrogates in Rs modeling and shows that air temperature and soil temperature are highly correlated and that they explain similar amounts of Rs variation; however, average monthly precipitation between 1961 and 2014, rather than monthly precipitation for a specific year, is a better predictor in global Rs modeling. Chapter 3 quantifies the uncertainty generated by four different assumptions of global Rs models. Results demonstrate that the time-scale of the data, among other sources, creates a substantial difference in global estimates, where the estimate of global annual Rs based on monthly Rs data (70.85 to 80.99 Pg C yr-1) is substantially lower than the current benchmark for land models (98 Pg C yr-1). Chapter 4 simulates future global Rs rates based on two temperature scenarios and demonstrates that temperature sensitivity of Rs will decline in warm climates where the level of global warming will reach 3°C by 2100 relative to current air temperature; however, these regional decelerations will be offset by large Rs accelerations in the boreal and polar regions. Chapter 5 compares CO2 fluxes from turfgrass and wooded areas of five parks in Blacksburg, VA and tests the ability of the Denitrification-Decomposition model to estimate soil temperature, moisture and CO2 flux across the seasons. Cumulatively, this work provides new insights into the current and future spatial and temporal heterogeneity of Rs and its relationship with environmental factors, as well as key insights in upscaling methodology that will help to constrain global Rs estimates and predict how global Rs will respond to global warming in the future.
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    Greening the city: are we bringing foresters to the table?
    Wiseman, P. Eric; Day, Susan D. (Society of American Foresters, 2018-06-15)
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    Growth and Physiology of Several Urban Tree Species in Soils Disturbed by Construction Fill or Compaction
    Day, Susan D. (Virginia Tech, 1999-08-06)
    Experiments were conducted to determine the effects of applying fill soil around existing trees and mechanisms for species tolerance to soil compaction, both common site disturbances in urban forestry. Groups of 22-year-old white oak (Quercus alba) and 13-year-old sweetgum (Liquidambar styraciflua) were subjected to one of three treatments: a control, fill (20 cm of subsoil spread over the root zones), and compacted fill (same as fill soil, but compacted). Additionally, individual trees had tree wells (fill soil pulled away from trunks), or not. After three years, treatments had no consistent effect on tree growth, chlorophyll fluorescence, or soil respiration. However, soil treatments disrupted normal soil moisture patterns at both sites. Roots of white oak grew into fill layers, although overall root growth was not significantly affected by treatment. Sweetgum roots grew very little into fill soils. However, root distribution shifted upward in the original soil under uncompacted fill. Other factors associated with raising the soil grade, such as soil trafficking and root severance, may be largely responsible for the tree decline often attributed to construction fill. Another experiment investigated the relationship between tolerance of wet soils and the ability to grow in compacted soils. It was hypothesized that tree species tolerant of wet soils would have opportunities for root growth in compacted soil when high soil moisture reduced soil strength. Seedlings of flowering dogwood (Cornus florida), a species intolerant of inundation, and silver maple (Acer saccharinum), a bottomland species, were grown in a loam soil maintained at various combinations of soil strength and soil matric potential. In moderately compacted soil (1.5 g cm-3 bulk density), maple seedlings, but not dogwoods, had greater root growth rate, root length per plant, and ratio of root length to root dry weight in the wet soil (0.006 MPa soil matric potential) than in the moist and dry soils (0.026 and 0.06 MPa, respectively). No such effect was detected in highly compacted soil (1.7 g cm-3). It can be concluded that silver maple roots can grow in moderately compacted soil when high soil water content decreases soil strength, whereas dogwood is unable to take advantage of this opportunity.
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    Influence of Tree Planting Program Characteristics on Environmental Justice Outcomes
    Ketcham, Cene Walstine (Virginia Tech, 2015-09-11)
    Urban trees provide a variety of benefits to human physical and mental health. However, prior research has shown that urban tree canopy is unevenly distributed; areas with lower household incomes or higher proportions of racial or ethnic minorities tend to have less canopy. Urban tree benefits are largely spatially-dependent, so this disparity has a disproportionate impact on these communities, which are additionally subject to higher rates of health problems. Planting programs are a common way that municipal and nonprofit urban forest organizations attempt to increase canopy in cities. Increasing canopy in underserved communities is a commonly desired outcome, but which of the wide range of programmatic strategies currently employed are more likely to result in success? This research uses interviews with planting program administrators, spatially referenced planting data, and demographic data for six U.S. cities in order to connect planting program design elements to equity outcomes. I developed a planting program taxonomy to provide a framework for classifying and comparing programs based on their operational characteristics, and used it along with planting location data to identify programs that had the greatest reach into low-income and minority area. I found that highly integrated partnerships between nonprofit and municipal entities, reduced planting responsibility for property owners, and concentrated plantings that utilize public property locations to a high degree are likely to improve program penetration into low-income and minority areas. These findings provide urban forestry practitioners with guidance on how to more successfully align planting program design with equity outcomes.
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    The Influence of Urban Soil Rehabilitation on Soil Carbon Dynamics, Greenhouse Gas Emission, and Stormwater Mitigation
    Chen, Yujuan (Virginia Tech, 2013-08-09)
    Global urbanization has resulted in rapidly increased urban land. Soils are the foundation that supports plant growth and human activities in urban areas. Furthermore, urban soils have potential to provide a carbon sink to mitigate greenhouse gas emission and climate change. However, typical urban land development practices including vegetation clearing, topsoil removal, stockpiling, compaction, grading and building result in degraded soils. In this work, we evaluated an urban soil rehabilitation technique that includes compost incorporation to a 60-cm depth via deep tillage followed by more typical topsoil replacement. Our objectives were to assess the change in soil physical characteristics, soil carbon sequestration, greenhouse gas emissions, and stormwater mitigation after both typical urban land development practices and post-development rehabilitation. We found typical urban land development practices altered soil properties dramatically including increasing bulk density, decreasing aggregation and decreasing soil permeability. In the surface soils, construction activities broke macroaggregates into smaller fractions leading to carbon loss, even in the most stable mineral-bound carbon pool. We evaluated the effects of the soil rehabilitation technique under study, profile rebuilding, on soils exposed to these typical land development practices. Profile rebuilding incorporates compost amendment and deep tillage to address subsoil compaction. In the subsurface soils, profile rebuilding increased carbon storage in available and aggregate-protected carbon pools and microbial biomass which could partially offset soil carbon loss resulting from land development. Yet, urban soil rehabilitation increased greenhouse gas emissions while typical land development resulted in similar greenhouse gas emissions compared to undisturbed soils. Additionally, rehabilitated soils had higher saturated soil hydraulic conductivity in subsurface soils compared to other practices which could help mitigate stormwater runoff in urban areas. In our study, we found urban soil management practices can have a significant impact on urban ecosystem service provision. However, broader study integrating urban soil management practices with other ecosystem elements, such as vegetation, will help further develop effective strategies for sustainable cities.  
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    Managing Landscapes to Meet Emerging Global Challenges
    Badgley, Brian D.; Daniels, W. Lee; Day, Susan D.; Eick, Matthew J.; Ervin, Erik H.; Steele, Meredith K.; Stewart, Ryan D.; Strahm, Brian D.; Xia, Kang; Zipper, Carl E. (Virginia Tech, 2017-05-15)
    Our vision is to create a program dedicated to accelerating innovation that improves the quality, efficiency, and resilience of human dominated landscapes, including our cities, farms, and industrial lands. Humans dramatically alter and manipulate the global landscape for food and fiber production, mineral extraction, urban development, waste disposal and many other purposes. Impacts to essential ecosystem functions and values range from local (e.g. mining and land development) to global (e.g. carbon emissions) with a clear need for development of appropriate management systems for their mitigation. By using a systems approach that interfaces environmental scientists and ecologists with relevant disciplines, this proposed signature area within Global Systems Science (GSS) will build upon existing group strengths in soil remediation, water quality, hydrology, urban soils, land reclamation, agroecosystem management, forest ecology, wetland restoration, soil-waste management and integrated modeling across multiple spatial and temporal scales to develop a more holistic approach to landscape management. We will also...
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    A Mycorrhizal Model for Transactive Energy Markets
    Gould, Zachary M. (Virginia Tech, 2022-09-08)
    Mycorrhizal Networks (MNs) facilitate the exchange of resources including energy, water, nutrients, and information between trees and plants in forest ecosystems. This work explored MNs as an inspiration for new market models in transactive energy networks, which similarly involve exchanges of energy and information between buildings in local communities. Specific insights from the literature on the structure and function of MNs were translated into an energy model with the aim of addressing challenges associated with the proliferation of distributed energy resources (DERs) at the grid edge and the incorporation of DER aggregations into wholesale energy markets. First, a systematic review of bio-inspired computing interventions applied to microgrids and their interactions with modern energy markets established a technical knowledge base within the context of distributed electrical systems. Second, a bio-inspired design process built on this knowledge base to yield a structural and functional blueprint for a computational mycorrhizal energy market simulation. Lastly, that computational model was implemented and simulated on a blockchain-compatible, multi-agent software platform to determine the effect that mycorrhizal strategies have on transactive energy market performance. The structural translation of a mapped ectomycorrhizal network of Douglas-firs in Oregon, USA called the 'wood-wide web' created an effective framework for the organization of a novel mycorrhizal energy market model that enabled participating buildings to redistribute percentages of their energy assets on different competing exchanges throughout a series of week-long simulations. No significant changes in functional performance –- as determined by economic, technical, and ecological metrics – were observed when the mycorrhizal results were compared to those of a baseline transactive energy community without periodic energy asset redistribution. Still, the model itself is determined to be a useful tool for further exploration of innovative, automated strategies for DER integration into modern energy market structures and electrical infrastructure in the age of Web3, especially as new science emerges to better explain trigger and feedback mechanisms for carbon exchange through MNs and how mycorrhizae adapt to changes in the environment. This dissertation concludes with a brief discussion of policy implications and an analysis applying the ecological principles of robustness, biodiversity, and altruism to the collective energy future of the human species.
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    A Novel Approach to Communal Rainwater Harvesting for Single-Family Housing: A Study of Tank Size, Reliability, and Costs
    Semaan, Marie (Virginia Tech, 2020-04-09)
    An emerging field in rainwater harvesting (RWH) is the application of communal rainwater harvesting system. This system's main advantage compared to individual RWH is the centralization of water treatment, which some users of individual RWH find difficult to maintain. Despite alleviating one concern, this communal approach does not increase the RHW system's (RWHS) reliability nor necessarily satisfy all water demands, and hence is not a major improvement in terms of system performance. This research tackles this challenge with a novel approach to communal RWH for single-family houses. Instead of the traditional communal approach to RWH which uses only one storage location, we propose connecting multiple single-family homes' RWHSs to a communal backup tank, i.e., capturing overflow from multiple RWHS, which will increase reliability and water demand met in a way that will significantly improve the current performance of communal RWH. The proposed system will potentially maximize the availability of potable water while limiting spillage and overflow. We simulated the performance of the system in two cities, Houston and Jacksonville, for multiple private and communal storage combination. Results show that volumetric reliability gains, of 1.5% - 6% and 1.5% - 4%, can be achieved for seven to ten and six to seven connected households, respectively, for Houston and Jacksonville if the emphasis is on volumetric reliability (VR). As per total storage capacity, the system achieves higher VR gains for lower total storage capacity in Houston while the system achieves higher VR gains for higher total storage capacities in Jacksonville. With regards to the total cost of ownership per household for the individual system and for the communal storage system, the lifecycle cost of the system was performed using the Net Present Value (NPV) method, with an interest rate of 7% over 30 years. The NPV of the total system costs per household in the city of Houston is lowest for nine to ten connected households, as well as comparable to the base case of a rainwater harvesting system that is not connected to a communal tank for seven and eight connected households. This communal system is more resilient and can be a worthy addition to water and stormwater infrastructures, especially in the face of climate change.
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    An Overview of Renewable Energy and its Effects on Wildlife and the Environment
    Dodds, Richelle (Virginia Tech, 2016-05-12)
    As concern over greenhouse gas (GHG) emissions from conventional fossil fuel sources rises, energy developers look toward renewable resources as prime candidates for “cleaner” and “greener” energy production. This paper provides an overview of the main environmental and wildlife effects of five of the major renewable energy sources: wind, solar, geothermal, biomass, and hydro. Examples of the effects of pollution, habitat degradation, land use, species mortality, and Endangered Species Act (ESA) listed species are discussed. Avoidance and mitigation suggestions are reviewed. Before-after-control-impact assessments and habitat conservation plans can aid a developer in siting of a renewable energy project. The developer must weigh the economical and environmental costs of a project. Mitigation efforts should be made before construction, however, these efforts are not always clear and can be lost without proper enforcement. Early and continuous contact between developers and regulatory agencies can prevent increases in project time. Ignoring species and environmental protection guidelines up front can cause increased costs later on to mitigate the disturbances. Areas lacking research and viable data are addressed. Additional research is needed on species located in energy-rich habitats, particularly for ESA-listed species and species that are believed to be strongly affected by the new development. Currently, plans for carbon-based energy production are duplicated and utilized for environmental and species conservation with regards to renewable energy. In order for wildlife and environmental specialists to effectively plan for renewable energy developments and perform effective mitigation efforts, additional rigorous studies will need to be conducted. These plans will need to be tailored to each renewable energy source in order for environmental planners to recognize the differences between them.
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    Perceived Outcomes of a Community-based Urban Agriculture and Nutrition Education Program: A Case Study of Common Good City Farm’s Green Tomorrows Program in Washington, D.C.
    Trutko, Alexander (Virginia Tech, 2014-07)
    Urban farm education programs can provide opportunities for community members to acquire skills and knowledge related to agriculture, food production, and nutrition. This project proposed a case study focusing on the Common Good City Farm’s Green Tomorrows program, an urban agriculture and nutrition education program for residents of Washington D.C., which aims to increase participant level of food security, ability to grow crops in urban locations, and knowledge of nutrition, food preparation, and food budgeting. The purpose of this study was to gain a better understanding of how effectively the Green Tomorrows program accomplished its intended program goals and outcomes. Semi-structured interviews were conducted with program staff and recent regular participants to: 1) identify similarities and differences between the staff and participant stated program goals; 2) determine key program impacts on participants; and 3) generate programmatic recommendations. The semi-structured interview guides included questions that revealed staff and program graduates perceptions concerning goals and outcomes of the program. Participants described how the program’s food distribution resulted in increased consumption of produce, which contributed to improved food security. They reported greater knowledge of agricultural methods and healthy eating, and the ability to prepare and shop for healthily food post-program completion. Overall, the Green Tomorrow’s program outcomes aligned with staff and participant expectations, and positively influenced participant’s food security, knowledge of nutrition, food preparation, and food budgeting skills through the community programming activities.
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    Planting on Your Septic Drain Field
    Day, Susan D.; Silva, Ellen (Virginia Cooperative Extension, 2010-10-15)
    By following a few simple guidelines outlined in this publication, you will be able to answer the question, 'What should I plant over a septic system's leach field?'