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 White oak (Quercus alba L.) mortality in response to biotic and abiotic factors and climate change in the eastern United States(University of Missouri--Columbia, 2024) Khadka, Saaruj; He, Hong S.White oak mortality in the eastern United States presents significant challenges for forest conservation efforts. Understanding the spatial patterns and underlying processes, impacts of biotic and abiotic factors, and climate change is crucial for effective management of white oak forest in the eastern United States. White oak mortality (WOM) can have clustered patterns at local scale due to stand development and soil conditions. While there might be a random WOM pattern due to drought events and uniform pattern from soil conditions and moisture availability at broad scale. White oak mortality is also greatly impacted by biotic factors such as basal area, stand density, and abiotic factors such as spring precipitation and winter temperature. Chapter I laid out the overall objectives and justifications for chapter II, III, and IV. It stated ecological importance of white oaks in the eastern US and its conservation for maintaining regional biodiversity. This chapter addressed spatial pattern distribution, role of biotic and abiotic factors, and climate change impacts on WOM rate. In this chapter, there was a specific description on data processing, result analyses, major findings, and summaries from chapters. Chapter II investigated the spatial patterns in southern, central, and northern region of WOM rate across the eastern US. I compiled multicycle Forest Inventory and Analysis data from 1998 to 2019 to capture WOM rate. Results of this chapter found clustered pattern mostly at local scale across the southern and northern regions of WOM rate. However, the central region indicated random patterns at mid scales and uniform pattern at a broad scale across all regions. The observed various spatial pattern of WOM rate explored the underlying factors associated WOM. This study provides an important basis for depicting the broad, general pattern of WOM and understanding the possible factors impacting WOM rate at varying scales. Chapter III identified the most important variables affecting WOM rate by integrating biotic, abiotic factor and forest inventory data. I ranked biotic and abiotic variables in response to WOM rate by integrating forest inventory data and Classification and Regression Tree. I also identified that basal area was first in the hierarchical ranking denoting major impacting variable to WOM rate. I demonstrated that biotic factors were significantly more important than abiotic factors, in which basal area was very important followed by stand density, summer temperature, summer and spring precipitation, and elevation. This research contributes valuable insights into the biotic and abiotic factors impacting white oak forest and highlight the importance of holistic approach in addressing complex environmental challenges. Chapter IV investigated the situation of WOM rate under climate change in the intermediate scenario i.e., SSP2-4.5. I projected WOM rate to the year 2025 to 2099 with break off at three averaged time intervals i.e., early (2025-2049), mid (2050-2074), and late (2075-2099). I analyzed five different climate models by integrating remote sensing and Coupled Model Intercomparison Project Phase 6 climate variables. I focused on four seasonal variables mainly summer and winter temperature and spring and summer precipitation. Results of this chapter showed that WOM rate will increase mostly in the southern region of our study area whereas northern region mostly witness a decrease in WOM rate. I also identified that there will be a increase in few areas as well as very less areas for decrease in WOM rate in the central region of our study area. Rising temperature and shifting precipitation pattern will increase WOM rate while ongoing management efforts will decrease WOM rate at northern region. This research points out important insights into highly impacted as well as less impacting areas of WOM rates under changing climate. Chapter V is the overall conclusions that summarizes major findings. Chapter II identified mainly clustered pattern at local scale associated with stand-level competition and soil characteristics. Random pattern at local and broad scale was associated with stochastic events such as droughts and other climate stressors. The uniform pattern at broad scale was associated with land use practices and forest management efforts. Chapter III pointed out that basal area was the main biotic variable impacting white oaks due to massive competition of resources during natural thinning. Likewise, climate, terrain, and soil characteristics also found important in impacting white oaks in the second and third tier, respectively. Chapter IV demonstrated that WOM rate will increase mainly in the southern region due to rising temperature and shifting precipitation. The central and northern region will experience decrease as well as moderate increase due to possible forest management efforts. However, majority areas will also remain unchanged for WOM rate due to ongoing management efforts.Item Bioremediation of atrazine and its metabolites using a novel Bacillus thuringiensis spore-based enzyme display system(University of Missouri--Columbia, 2023) Hsu, Shu-Yu; Lin, Chung-Ho; Stewart, George C.Bacillus thuringiensis spore-based display system has been shown to be an excellent biocatalyst platform to express the high density of the targeted enzymes to catalyze the chemical reactions. To demonstrate Bacillus thuringiensis spore-based display system can be a superior and more cost-effective approach for enzymatic bioremediation of contaminated soils as compared to conventional enzymatic techniques, this study focused on exploring and testing the utility of the biocatalyst system for decontamination of a persistent contaminant, atrazine (ATR). The first three enzymes, AtA, AtzB, and AtzC, in Pseudomonas sp. strain ADP ATR degradation pathway were incorporated into the B. thuringiensis spore display system to decontaminate ATR and its metabolites to less toxic metabolite. The environmental risk of applying the B. thuringiensis spore display system in the field was also investigated. Our findings showed that the AtzA-bearing spore exhibited enhanced enzymatic activity and stability and less washout as compared to free recombinant AtzA enzymes in soil. More than 90 percent of applied ATR (46 M [mu]10 mg L-1]) in the soil was detoxified by AtzA-bearing spores in 24 hours. Furthermore, the optimal ratio of AtzA- and AtzB-bearing spores decontaminate more than 80 percent fortified 34.5 nM (7.5 [mu]g L-1) of ATR in surface water within 24 hours, and the fortified ATR and its metabolite, hydroxy atrazine (HA), in surface water was completely converted to the end metabolite N-isopropylammelide (NiPA) at the end of 96 hours. Additionally, more than 67 percent of applied NiPA was degraded by 1 mg AtzC-bearing spores with the corresponding production of cyanuric acid in water. The enzymatic kinetics study of AtzC-bearing spores provides insightful information for determining the optimal ratio among AtzA-, AtzB-, and AtzC-bearing spores in the one-pot reactions for ATR degradation. Lastly, this is the first study to monitor the germination of B. thuringiensis spore in both surface water and soil. We found little to no germination from AtzA-bearing spores as observed in the sterile surface water incubated in the laboratory, while a small percentage (2.1-2.4 percent) of AtzA- bearing spores germinated in the sterile soil incubated in the laboratory after 4 days. In conclusion, this study demonstrated ATR decontamination by multiple enzymes delivered by B. thuringiensis spore in one-pot reactions in surface water and laid an important foundation for the environmental application of the novel B. thuringiensis spore display system. A review of possible delivery system for the novel enzyme expression platform was also included. Immediately after the outburst of the global COVID-19 pandemic in 2020, the author endeavored to serve the community as a scientist to take on the major challenge of public health. Therefore, the author has decided to suspend the Ph.D. study and direct all the efforts and energy to contribute her scientific knowledge to protect public health in responding to one of the most critical global health crises in human history. Through joining the Missouri Wastewater Surveillance Taskforce since the pandemic, a novel approach was developed to capture the real-time population dynamic for normalizing the SARS-CoV-2 viral load in the wastewater. This strategy was superior to the current approach recommended by the CDC, and it has been successfully used for predicting the infected population within the communities. This novel normalization approach has been adopted by the federal City of Bon, Germany, and the Canadian government agencies for tracking the COVID-19 infection using WBE. This strategy can be implemented to track not only infectious diseases but also to map opioids or other drug usage in the community in the future.Item Insight into the roles of prescribed fire and hardwood competition in the survival and growth of shortleaf pine throughout its early life(University of Missouri--Columbia, 2023) Fillingim, Hope Marie; Knapp, BenjaminShortleaf pine is an economically and ecologically important species that was once prevalent across the southeastern United States, and there is growing interest in its restoration throughout its former range. One challenge with restoring shortleaf pine is competition from hardwoods. In Missouri specifically, many sites formerly occupied by shortleaf pine are now dominated by oak species with established and highly competitive advanced regeneration. Prescribed fire is a tool often used in shortleaf pine management, with varying effects at different life stages. This dissertation incorporates results from four studies on the early life stages of shortleaf pine in the Missouri Ozarks. The first study examined the direct and indirect effects of fire on shortleaf pine seeds. The second study focuses on survival, sprouting, and growth following prescribed burning of shortleaf pine and oak seedlings and saplings of various sizes from 0-15 cm basal diameter, and can be used to help managers determine the best time to use prescribed fire to manage for shortleaf pine success in mixed oak-pine forests. The third focuses on the growth and survival of planted shortleaf pine seedlings under a range of overstory conditions and highlights the importance of competitive status relative to hardwood competition for survival of shortleaf pine regeneration during their first decade. The fourth study uses tree-ring analysis to study growth response of shortleaf pine planted following a 2002 tornado in two stands with different known histories of management activities, specifically prescribed burning and mechanical release, across a range of competition levels. Taken together these findings provide insight into the roles of prescribed fire and hardwood competition in the survival and growth of shortleaf pine throughout its early life.Item Corridors and deer-vehicle collisions along Missouri interstate highways(University of Missouri--Columbia, 2022) Acharya, Shikha; Morgan, MarkA total of 3,639 deer-vehicle collisions (DVCs) were reported on Missouri roadways in 2020, resulting in 348 injuries and 5 deaths. Missouri is ranked 15th nationwide for this type of accident. Of the DVCs, 490 occurred along 1,200 miles of urban and rural interstates in Missouri (I-29, I-35, I-44, I-49, I-55, I-57, I-64, I-70, I-155, I-170, I-255, I-270, I-435, and I-470). Despite the small number of DVCs on interstates (<15 percent), these sites are high-speed impacts, averaging $6,717 per crash. This study investigated DVCs on interstate highways using secondary data obtained from the Missouri State Highway Patrol. Each pair of longitude and latitude coordinates was uploaded into Google Maps and observed on a 200-foot scale view. Aerial photography and street-side images were used to examine the possible influence of land use characteristics and corridors adjacent to each location. Of the 490 DVC sites examined, 449 (91.6 percent) were near a natural (47 percent) or cultural (31 percent) corridor, and sometimes both (22 percent). Natural corridors consisted mostly of vegetation (65.7 percent), water (31.8 percent), and dry creeks (2.5 percent), whereas cultural corridors were secondary roads (36.1 percent), fence rows (22.6 percent), public utilities (22.2 percent) and overpasses (19 percent). Results showed that the distance from the nearest corridor to the collision point was about 350 feet, reinforcing the importance of landscape connectivity. These findings, when combined with other studies, can be useful to warn motorists at certain times (dawn/dusk) and seasons (fall/winter) at specific locations (hotspots) along Missouri interstates when the risk of a collision with deer is greatest. St. Louis and Kansas City had the most concentrated DVC sites statewide, drawing attention to urban deer and city drivers.Item Effects of dormant season soil flooding and soil temperature on pin oak (Quercus palustris) seedlings(University of Missouri--Columbia, 2022) Vaughan, Ian Matthew; Knapp, Benjamin O.Bottomland forests are the dominant forest cover along the Mississippi Alluvial Valley. Changes in land use and hydrologic regimes have reduced the area of bottomland forest, putting pressure on the remaining area to meet multiple objectives. To maintain migratory waterfowl habitat, some forests are managed as greentree reservoirs and artificially flooded during the fall and winter. Red oaks are a desirable component of these forests for their acorn production, but oak decline and inadequate recruitment pose problems for maintaining quality habitat. Artificial flooding regimes may be a driving factor in oak decline, as flood timing and duration may be outside of historic conditions. Previous studies have shown growing season floods can inhibit root growth, but the impacts of dormant season flooding are not as well studied. We conducted a greenhouse study to determine how winter flooding at different soil temperatures affects the growth and development of Quercus palustris (pin oak) seedlings. We examined the effects of soil temperature and dormant season flooding on Q. palustris seedlings using insulated water baths at 5, 10, and 15 degrees C. Half of the seedlings received soil flooding for 60 days from January to March, after which floodwater was drained for the remainder of the study. Seedlings were harvested before, during, and after flooding. Root length was determined using scanned images and WinRHIZO (Regent Instruments, Inc), after which samples were oven-dried to determine mass. During soil flooding, root mass was significantly less in flooded seedlings than those that were not flooded. However, following drainage this difference was no longer present. By the end of the experiment, seedlings that received flooding exhibited greater lateral root mass and length than those that had not been flooded. Flooding had minor positive impacts on aboveground variables, such as increased stem area, but did not significantly impact aboveground seedling biomass. These findings suggest that Q. palustris may experience temporary stress during dormant season flooding but can recover without lasting effects. While these results seem promising for current greentree reservoir management practices, care should be taken in applying them to field conditions.