Strawberries are considered an important crop in California where in 2018 it was in the top 5 valued fruit and vegetable commodities valued at $2.84 billion accounting for 88% of the total U.S. production. Strawberry production can be severely impacted by soilborne pathogens that can affect strawberry roots, crowns and leaves which can result in plant mortality. As much as 50 to 60% mortality can occur in one field. Pathogens responsible for such losses include Colletotrichum acutatum (syn.C. nymphaeae), Macrophomina phaseolina and Verticillium dahliae. With the phaseout of methyl bromide, host resistance and an understanding of host-pathogen interactions can play an important role in control of these diseases. A two-year study was conducted in order to evaluate host resistance of anthracnose in 105 cultivars and elite breeding lines developed by six strawberry breeding programs. Cultivars and elite breeding lines were inoculated using three local isolates in both years. All breeding programs provided genotypes that had a wide range of anthracnose susceptibility ranging from 0 to 100% mortality during both years. In both years an average of 78% of all the plant mortality occurred by 1 January. From the 105 cultivars and elite breeding lines, 30 cultivars were common to both years. Of these 30 cultivars, nine of them differed in their disease susceptibility between experiments by more than 20%. This suggests that several years of field evaluation may be necessary to determine susceptibility to anthracnose. Popular cultivars that represent the spectrum of susceptibility are Monterey (susceptible), Festival (moderately resistant), and Sensation (resistant). A second study was conducted toevaluate pathogen colonization of resistant and susceptible strawberry cultivars, testing interactions among crown and root plant tissue and two sampling timings. These cultivars were challenged with two soilborne pathogens, Macrophomina phaseolinaand Verticillium dahliae,over two years. Existing qPCR protocols for M. phaseolina and V. dahliae were used in order to quantify how much pathogen DNA was detected in crown and root samples. For the 2016-2017 V. dahliae trial there were significant effects for cultivar. Cultivar Benicia had significantly higher pathogen DNA compared to resistant cultivars Marquis, UC-12 and Camino Real. Susceptible cultivar BG 1975 had significantly less pathogen DNA compared to resistant cultivars San Andreas and Petaluma. In the 2017-2018 V. dahliaetrial pathogen DNA amount was not significantly different based on cultivar, plant part colonization, or the sampling period. In the 2017-2018 M. phaseolina trial all three of the fixed factors, cultivars, plant part colonization and sampling period were statistically significant. Cultivar ‘Sweet Ann’ had a significantly higher level of M. phaseolinaDNA in the early vs. the late sampling.

Uncertainty in climate change plays a major role in watershed systems. The increase in variability and intensity in temperature and precipitation affects hydrologic cycle in spatial and temporal dimensions. Predicting uncertainty in climate change impacts on watershed systems can help to understand future climate-induced risk on watershed systems and is essential for designing policies for mitigation and adaptation. Modeling the temporal patterns of uncertainties is assessed in the New England region for temperature and precipitation patterns over a long term. The regional uncertainty is modeled using Python scripting and GIS to analyze spatial patterns of climate change uncertainties over space and time. The results show that the regional uncertainty is significant in variation for changes in location and climatic scenarios. Watershed response to climate change under future scenarios is assessed using hydrologic simulation modeling for the Connecticut River watershed. Changes in water budgets are assessed for each of the subbasins using spatial analysis and process modeling using GIS and Soil and Water Assessment tool (SWAT). The results show that climate change uncertainty in precipitation and temperature can lead to uncertainty in both quantity and quality in the watershed system. A spatiotemporal, dynamic model was applied to subbasins within the Chicopee River Watershed to estimate climate change uncertainty impacts at a micro scale. These changes were assessed relative to changes in land use and climatic change. The results show that there is a significant potential for climate change to increase evaporation, watershed runoff and soil erosion rates and this varied with climate change uncertainty. Finally, water sustainability gradient analysis was applied to the Volga River watershed in Russia to assess potential climate change impacts by combining with downscaled Global Circulation Model estimates and spatial assessment. Results show that runoff and evapotranspiration are projected to increase with potential for more localized floods and drought events effecting both water resources and food supply. Overall results show that climate change uncertainty can impact watershed systems and spatial and temporal assessments is important for developing strategies for adaptation to climatic change conditions at local and regional scales.

Maintaining flows and quality of water resources is critical to support ecosystem services and consumptive needs. Understanding impacts of changes in climate and land use on ecohydrologic processes in a watershed is vital to sustaining water resources for multiple uses. This study completes a continental and regional scale assessment using statistical and simulation modeling to investigate ecohydrologic impacts within watershed systems. Watersheds across the continental United States have diverse hydrogeomorphic characters, mean temperatures, soil moistures, precipitation and evaporation patterns that influence runoff processes. Changes in climate affect runoff by impacting available soil moisture, evaporation, precipitation and vegetative patterns. A one percent increase in annual soil moisture may cause a five percent increase in runoff in watersheds across the continent. Low soil moisture and high temperatures influence runoff patterns in specific regions. Spring runoff is increased by the influence Spring soil moisture, Winter and Spring evaporation, and Winter and Spring evaporation. Spring runoff is decreased by increases in Winter and Spring temperatures and increases in the vegetation index. Winter runoff is affected by maximum vegetative index, temperature, soil moisture, evaporation and precipitation. Contributing factors to runoff are influenced by geomorphic and seasonal variations requiring strategies that are site-specific and use system-wide information. Regional scale watershed analysis investigates the influence of landscape metrics on temporal streamflow processes in multiple gauged watersheds in Massachusetts, U.S.A. Time of concentration, recession coefficient, base flow index, and peak flow are hydrologic metrics used to relate to landscape metrics derived using FRAGSTAT software. Peak flow increases with increasing perimeter-area fractal dimensions, and Contagion index and decreases as Landscape Shape Index increases. There was an increasing trend in the fractal dimension over time indicative of more complex shape of patches in watershed. Base flow index and recession coefficient fluctuated from low to high decreasing recently. This could be indicative of open space legislation, conservation efforts and reforestation within the state in the last ten years. Coastal systems provide valuable ecosystem services and are vulnerable to impacts of changes in climate and continental land use patterns. Effects of land use and climate change on runoff, suspended sediments, total nitrogen and total phosphorus are simulated for coastal watersheds around the Boston Bay ecosystem. The SWAT (Soil and Water Assessment Tool) model, a continuous-time, semi distributed, process-based model, is used to simulate the watershed ecohydrologic process affecting coastal bodies. Urbanization in watersheds increased runoff by as much as 80% from the baseline. Land use change poses a major threat to water quality impacts affecting coastal ecosystems. Total nitrogen increased average of 53.8% with conservative changes in climate and land use. Total phosphorus increased an average of 57.3% with conservative changes in land use and climate change. Climate change alone causes up to 40% increase in runoff and when combined with a 3.25% increase in urban development runoff increased an average of 114%. Coastal ecosystems are impacted by nutrient runoff from watersheds. Continued urbanization and changes in climate will increase total nitrogen, total phosphorus and suspended sediments in coastal ecosystems. Continental scale runoff is affected by soil moisture and vegetative cover. Cover crops, low tillage farm practices and natural vegetation contribute to less runoff. Developing policies that encourage protection of soil structure could minimize runoff and aid in maintaining sustainable water resources. Best Management Practices and Low impact development at the national level with continued stormwater legislation directed towards sustainable land use policy will improve water quantity and quality. Fragmentation observed in Massachusetts increases the number of urban parcels and decreases the size of forested areas. Faster runoff patterns are observed but recent land management may be changing this runoff pattern. Municipal and state zoning ordinance to preserve open space and large forest patches will restrict urban growth to specific regions of a watershed. This could improve quantities of water available to ecosystems. Increases in total nitrogen, phosphorus and suspended sediments to coastal ecosystems can be minimized with use of riparian buffers and Best Management Practices within coastal watersheds. Urbanization and climate change threatens coastal ecosystems and national policy to preserve and restrict development of coastal areas will preserve coastal ecosystem services.

<p>The primary goal of the research is to examine the expander manufacturing process of an industry, observe how the industry may sustainably be manufacturing elements throughout its entire manufacturing process, and analyze the advantages of doing so. It will also look at the challenges that would arise if these manufacturing processes were altered to make them more sustainable and environmentally friendly.</p>

The purpose of this study is to test the mechanical, dimensional stability, and weathering durability of OSB (oriented strand board) panels that have been treated with varying natural wood preservatives that were chosen from an array of natural antimicrobial compounds. Wood is increasing in popularity for new construction projects but has been limited by its vulnerability to biological degradation. The addition of natural antimicrobial compounds will increase the use life of wood-based strand board allowing its use to expand with the growing construction demand but has little data on how natural antimicrobial compounds impact different properties of the OSB. The preliminary specimens produced will be tested for mechanical, dimensional stability, and weathering durability properties, and then larger specimens will be made to test the properties at a larger scale.

<p dir="ltr">In this era of changing global climate and globalization, the intricate relationships between non-native organisms and their impacts on forest health are of paramount concern. Bark and ambrosia beetles are diverse groups of insects that are among the most intercepted insects at international ports of entry. Once established, these insects can vector pathogens and disrupt functional forest dynamics. Bark and ambrosia beetles are known to attack various tree species, including black walnut (<i>Juglans nigra</i>), a valuable timer and nut-producing tree native to Eastern North America. Non-native woodboring beetles provide unique opportunities for ecological studies and pest management. This research investigates the chemical ecology and microbial dynamics in black walnut ecosystems to fill critical knowledge gaps and address the pressing issues surrounding forest health and sustainable management.</p><p dir="ltr">In Chapter 1, I review the current literature describing the use of semiochemicals in bark and ambrosia beetle management, non-native scolytines as vectors of phytopathogens, and the use of nematodes as natural antagonists of fungal pathogens in trees.</p><p dir="ltr">In Chapter 2, I aim to identify attractant and repellent semiochemicals for the ambrosia beetle <i>Anisandrus maiche</i>, which is a first step in developing effective management strategies for this species. I found that conophthorin and verbenone are strong repellents and that this beetle is attracted to ethanol in a dose-dependent manner.</p><p dir="ltr">In Chapter 3, I tested the hypothesis that <i>Anisandrus maiche </i>will be influenced by volatiles of its nutritional fungal symbiont, <i>Ambrosiella cleistominuta,</i> and that these compounds may synergize with ethanol. I identified seven unique compounds from the fungus and two fungal alcohols in the field. I found isobutyl alcohol to repel <i>A. maiche </i>while isoamyl alcohol has seasonal effects on <i>A. maiche </i>capture when paired with ethanol.</p><p dir="ltr">In Chapter 4, I aimed to characterize the assemblage of microorganisms residing on two non-native ambrosia beetles across diverse forest types. I tested the hypothesis that forest stand diversity and management regimes would affect the assemblage of microorganisms of ambrosia beetles. I found forest type influences the abundance of fungi and bacteria on <i>A. maiche </i>and <i>Xylosandrus crassiusculus</i> and that both beetle species transport genera of pathogenic fungi.</p><p dir="ltr">In Chapter 5, I test the hypothesis that inoculation with <i>Geosmithia morbida </i>alters the volatile profile of black walnut. I found one isolate of <i>G. morbida </i>induced changes in the volatile profile of black walnut bark and identified the compounds that changed relative to the control trees.</p><p dir="ltr">In Chapter 6, I tested the hypothesis that free-living fungivorous nematodes can modulate Thousand Cankers Disease severity. I found two genera of nematodes <i>Panagrolaimus </i>and <i>Aphelenchoides </i>to orient towards agents of the TCD system in Y-tube bioassays. <i>Aphelenchoides </i>sp. that were exposed to <i>G. morbida </i>grown on agar media augmented with black walnut bark extract significantly reduced <i>G. morbida </i>cankers in black walnut seedlings. This research has important implications for the management of TCD.</p><p dir="ltr">In Chapter 7, I summarize results from each of research chapter and discuss future research needs and directions to continue development of the knowledge surrounding chemical ecology and microbial dynamics of non-native scolytine beetles.</p>

<p>Understanding the response of forest carbon uptake and growth to interannual climate variability and forest management practices is important, given the large quantity of carbon stored in forests, and their significant role in the global carbon cycle. Since 2004, biometric and micrometeorological measurements were taken in an age-sequence (10-, 38- and 73-years-old as of 2012) of white pine (<em>Pinus strobes</em> L.) plantation forests in southern Ontario, Canada, providing an 8 year record of carbon sequestration, growth and climate. The 73-year old conifer site was thinned in early 2012, where 25% of trees were removed to improve light and water dynamics of this stand, providing an opportunity to study the impacts of thinning on its carbon cycle. Additionally, in 2012, similar biometric and micrometeorological measurements were initiated in a naturally-regenerated, managed 80-year-old deciduous (Carolinian) forest, located in close proximity to the pine stands. Similar to the conifer sites, the deciduous site is also a managed forest. The objectives of this study were to determine differences in carbon pools and carbon sequestration capacity: (a) across an age-sequence of afforested, managed conifer stands; (b) between similarly-aged managed coniferous and deciduous stands; and (c) in a mature conifer plantation before and after a thinning event. Results show that carbon assimilated in the stem of mature white pine trees follows a linear growth trend, while that of young white pines shows an exponential increase in carbon assimilation over the course of this study. Overall, carbon sequestration increased with stand age across the age-sequence, except when disturbed by an event such as thinning. Thinning substantially reduced the live aboveground carbon pool (by 14%), while increasing woody debris (by 122%) due to logging residue left on-site. Comparison between the mature coniferous and deciduous stands, showed that total aboveground carbon storage within the pine stand (144 t C/ha) was generally higher than in the oak-dominated deciduous stand (83 t C/ha), despite both growing in similar soil and climate. While monthly tree growth exhibited a positive correlation with mean monthly temperature across all sites, tree growth negatively correlated with precipitation at the 10-year old white pine and 80-year old deciduous sites and no apparent correlation existed at the 73- and 38-year old sites. At the three coniferous stands, total annual net primary productivity (NPP) exhibited no correlation with mean growing season temperature or precipitation. This suggested that tree growth in young coniferous stands could be as sensitive as that of mature deciduous stands to precipitation. However, overall NPP seemed to be less sensitive to climatic variables across these stands, irrespective of their age and NPP may be driven more by stand physiology. Finally, eddy covariance and biometric estimations of NPP and NEP were compared, and results showed that although some growth trends do compare between the two techniques, magnitude discrepancies do exist and should be studied further. Results from this study will be informative to forest managers, forest conservationists and those interested in forest carbon sequestration.</p> / Master of Science (MSc)

Landslides are mass movements that affect infrastructure across East Tennessee, causing problems for the Tennessee Department of Transportation (TDOT). An assessment of conditions and locations of unstable slopes can aid TDOT in infrastructure management. Landslide susceptibility was evaluated for Anderson and Morgan counties, TN, off State Route 116 in the New River watershed. Susceptibility maps used a landslide inventory and six factors: elevation, slope, geology, distance from stream, rainfall, and curvature, input in forest-based classification and logistic regression models. Additionally, affected trees along these unstable slopes in Anderson and Morgan counties were cored to analyze mass movement impacts on tree rings. This research demonstrates the importance of causative factors used to model landslide susceptible areas and how trees rings can carry the signature of landslides. These two studies can help aid in mitigation practices for TDOT and potentially apply landslide susceptibility research to other parts of East Tennessee.

Quarterly samples were used to estimate assemblage-level (all species combined) fish production within three minimally-impacted, southern West Virginia streams. The total annual fish production estimate was highest in Slaunch Fork (37.52 kg∙ha-1∙y-1), a tributary of the Tug Fork River, and lowest in Cabin Creek (10.59 kg∙ha-1∙y-1), a Guyandotte River tributary. Creek Chub Semotilus atromaculatus, Mottled Sculpin Cottus bairdii and Blacknose Dace Rhinicthys atratulus were the most abundant species among sites, accounting for >90% of all sampled individuals. Reference condition criteria were also selected and metrics calculated for each of the three stream sites using a variety of established metrics. According to established criteria, all three of our sites scored high enough to be listed as “reference” sites. Third, a comprehensive GIS analysis was conducted in order to determine land use patterns and predict where similar assemblages would be present using various climatological and physical characteristics of our stream sites. These analyses revealed rapid expansion of surface mining activities putting many stream systems at risk.

Late Pleistocene American black bears (Ursus americanus) often overlap in size with Pleistocene brown bears (U. arctos), occasionally making them difficult to diagnose. Large U. americanus have previously been distinguished from U. arctos by the length of the upper second molar (M2). However, the teeth of fossil U. americanus sometimes overlap size with U. arctos. As such, there is need for a more accurate tool to distinguish the two species. Here, 2D geometric morphometrics is applied to the occlusal surface of the M2 to further assess the utility of this tooth for distinguishing U. americanus and U. arctos specimens. When combined with an Ecological Niche Model of U. americanus and U. arctos in North America from the Last Glacial Maximum, this morphometric technique can be applied to key regions. A case of two Pleistocene specimens previously identified as U. arctos from eastern North America exemplifies the utility of this combination.