Forestry electronic theses and dissertations (MU)
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The items in this collection are the theses and dissertations written by students of the Department of Forestry. Some items may be viewed only by members of the University of Missouri System and/or University of Missouri-Columbia. Click on one of the browse buttons above for a complete listing of the works.
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Item Characterization of bioactive compounds in American elderberry (Sambucus nigra subsp. canadensis) juices(University of Missouri--Columbia, 2025) Dwikarina, Amanda; Lin, Chung-HoAmerican elderberry (Sambucus nigra subsp. canadensis) is an emerging specialty crop in North America, valued for its rich composition of bioactive compounds, which have demonstrated nutritional and therapeutic potential. However, comprehensive chemical and functional characterization of American elderberry remain limited. This dissertation integrates advanced metabolomic analysis, bioassay screening, and molecular mechanism studies to elucidate the chemical diversity and antiviral activity of American elderberry. An untargeted ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC–HRMS) metabolomics analysis, combined with high-throughput bioassay screening, was employed to characterize juices from 18 propagated accessions and three established American elderberry cultivars. More than 100 putative bioactive compounds were identified, revealing genotype-dependent differences in metabolite composition. Cultivar Ozark and several wild accessions, such as accession 1911, displayed distinct chemical signatures. Among 32 tested compounds, 14 exhibited strong antioxidant activity, and six demonstrated antiviral effects against HIV-1, highlighting elderberry's potential in functional food and nutraceutical applications. This study further investigated the antiviral properties of American elderberry against the Influenza A Polymerase Acidic (PA) protein using fluorescence resonance energy transfer (FRET)-based endonuclease assay. Four cultivars, Ozark, accession 1892, 1196, and 2084, showed inhibition activity greater than 65% against PA activity, surpassing the European cultivar ‘Haschberg'. Several phenolic compounds, including gallic acid, myricetin, caffeic acid, and luteolin, displayed potent inhibition of PA endonuclease activity (IC₅₀ < 30 μM), suggesting their role as key bioactive constituents underlying elderberry's anti-influenza potential. A targeted ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC–MS/MS) method was developed and validated to quantify the bioactive compounds in American elderberry across 21 cultivars. The optimized UHPLC–MS/MS platform achieved excellent detection limits (< 1 ng/mL), minimized matrix effects, and provided accurate quantification of complex juice extracts. This study revealed genotype-dependent variation in metabolite composition, highlighting opportunities for targeted breeding and cultivar selection to enhance desired phytochemical traits, such as antioxidant capacity, antiviral bioactivity, and overall nutritional quality. Notably, wild-propagated accession 1199 exhibited high levels of cyanidin-based anthocyanins, suggesting its utility as a natural food color source. Phenolic acid compounds were found most abundant in accession 1196, whereas the flavonoid isorhamnetin 3-rutinoside was found highest in cultivar Ozark. Collectively, this work establishes a robust, comprehensive, analytical, and bioactivity framework for the characterization of American elderberry. By integrating metabolomic profiling, targeted quantification, and antiviral mechanism studies, these findings advance the understanding of elderberry phytochemistry and support its development as a source of functional and bioactive compounds for nutraceutical applications.Item White oak (Quercus alba) advance reproduction under uneven-aged management in the Ozark Highlands : seedling demography, establishment, and growth responses(University of Missouri--Columbia, 2025) Gross, Ryan; Stambaugh, MichaelWhite oak (Quercus alba L.) remains a foundation tree species in Missouri and elsewhere across eastern U.S. forests despite ongoing regeneration problems existing for nearly a century. These issues have led to region-wide structural and compositional forest shifts with the potential to permanently displace the species in forest ecosystems. Despite these regeneration issues, white oak exhibits resilient traits such as persistent survival, a capacity to occupy broad site conditions, and adaptations to drought and fire disturbance; most notably being its ability to reinitiate stem growth, or resprout, following top kill. Resprouting dynamics, critical to white oak's historical dominance, have been successfully promoted in even-aged management (EAM). However, a desire for uneven-aged management (UAM) has become prominent in Missouri's Ozark Highlands, where the species exists in its greatest density across its current range. Here, uneven-aged white oak forests provide a greater public acceptance of continuous canopy cover, opportunities to restore old-growth structures, and economic incentives of high-value timber products. This study evaluated UAM's impacts on white oak advance reproduction (wOAR) in the Ozark Highlands by merging dendrochronology and quantitative wood anatomy (QWA) methods to analyze seedling stems and roots at a cellular resolution. Age data revealed long-term understory residencies with notable variability in root-to-stem age relationships, and widespread resprouting even in fire's absence. Growth was strongly related to prolonged canopy openness, emphasizing light availability as a critical factor for recruitment success. These findings inform UAM strategies that may sustain white oak's ecological resilience, economic value, social benefit, and cultural legacy.Item Short-range machine learning forecasts - North Atlantic basin activity(University of Missouri--Columbia, 2025) Senter, Jason John; Lupo, AnthonyThis manuscript investigates the contemporary application of machine learning approaches for predicting complex system behavior within the physical sciences. Our study addresses this challenge by integrating three distinct techniques, culminating in a nuanced prediction method of accumulated cyclone energy for 2025 using an Echo State Network (ESN). Initially, complex wavelets are employed to detangle persistent signals within the datasets, enhancing our understanding of experimental bounds and signal behavior. Subsequently, recognizing the intrinsic periodicity of these systems, a novel distance ranking scheme is utilized to capture crucial temporal phase relationships among measures contributing to the target signal. Finally, this knowledge of the system is integrated into both linear and machine learning models, allowing for a rigorous evaluation of performance. These findings demonstrate that while potentially resource-intensive given sample constraints, the machine learning methodology proved highly versatile, suggesting future utility for deployment across a spectrum of datasets and forecasting scenarios.Item Enhancing the phytotechnologies toolkit : from pollutant prioritization to assessing the water relations of Populus L. genotypes grown for phytoremediation(University of Missouri--Columbia, 2025) Rogers, Elizabeth Rachel; Lin, Chung-HoPhytoremediation is a cost-effective technology that has been gaining momentum over the past few decades as a sustainable option for environmental pollution remediation. However, challenges remain to the optimization of phytoremediation systems, including: 1) selecting which pollutants to target with remediation systems, and 2) selecting ideal tree genotypes that both fulfill remediation objectives and are resilient to variable climatic conditions. To address the first challenge, an approach was developed for toxicity-based prioritization of contaminants to target with remediation systems. The comprehensive approach was then applied to a case study of Wisconsin landfills, wherein it was augmented with non-targeted analysis of high-resolution mass spectrometry data for putative identification of candidate compounds in landfill samples. To address the second challenge, a meta-analysis of Populus water use reported in the literature was conducted, and its influential factors were identified and compared. Then, a field trial was conducted to investigate the water use strategies of three hybrid poplar genotypes ('DN34', Populus deltoides Bartr. ex. Marsh x P. nigra L.; '9732-11', P. deltoides x P. nigra; 'NM2', P. nigra x P. maximowiczii A. Henry) in their fourth growing season that were grown for phytoremediation at a waste dumping site in Wisconsin. The approaches and results presented here can enable standardized pollutant prioritization and inform the selection of resilient poplar genotypes for phytoremediation applications.Item Interdisciplinary integration of silvopasture among livestock grazing systems as a strategy for natural resource management(University of Missouri--Columbia, 2025) Esparza-Harris, Kendra C; Conway-Anderson, Ashley; Knapp, BenjaminFor centuries, animal and natural resource management have maintained a balance of ecological sustainability and provisioning basic needs for human survival. Over time, civilizations evolved through the rise of agriculture, migration and trade, and technological advancements influencing land use change and natural resource management. However, land use decisions to meet the growing demands of society have contributed to modern issues, including climate change, natural resource depletion, landscape homogenization, fragmentation, and environmental degradation. To date, these issues are hindering agricultural communities' capacity in adapting to threats and maintaining a balance between ecological sustainability and productivity. This research incorporated qualitative and quantitative research methods aimed at assessing current livestock and resource management practices vulnerable to stressors, threatening sustainability of livestock systems and natural resources. Furthermore, this research focuses on evaluating avenues towards the integration of silvopasture within livestock systems to build adaptation and resilience within livestock production and natural resource management. A qualitative case study was conducted internationally to understand the stressors impacting pastoral and agricultural communities, and the potential for silvopasture components to aid in adaptation and resilience among commons resource management (Chapter 2). This study showed majority of communities were engaged in herding and farming activities, which were impacted by stressors causing constraints on commons resources and ensuing conflict between herders and farmers. Chapter 3 explored current livestock and forest management practices among Missouri livestock producers, assessing producers' perceptions and interests in the practice of silvopasture within livestock operations. Missouri livestock producers reported engaging in some level of livestock grazing and forest management practices, though gaps in understanding of practice and barriers hindered implementation of silvopasture. Chapter 4 examined using livestock for native landscape restoration by managing the invasive species Sericea lespedeza. This study showed that goats grazing has the capacity to impact the relative abundance of some vegetation classes following an initial grazing season. Grazing sericea lespedeza also showed benefits of parasitic control. These studies indicated interest in and applicability of silvopasture, demonstrating the opportunity to integrate the practice within livestock systems to enhance capacity for adapting to threats, conserving, and managing natural resources, restoring landscapes and gaining resilience.