Master of Science, University of Toledo, 2010, Biology (Ecology)

Extracellular enzymes are produced by both microbes and plants and directly mediate organic matter breakdown. These enzymes can be present on root surfaces or secreted by roots into the rhizosphere and are used to exploit pools of organic nutrients in the soil. Extracellular enzymes secreted by plant roots have received little attention outside of a few studies examining enzyme production on a small scale or in artificial/intensely managed environments. As a result, little is known about the extent of root enzyme activity and the degree to which these enzymes can be used by roots to exploit pools of organic nutrients in the soil. Additionally, comparative studies between native and invasive exotic plant root extracellular enzyme capabilities are lacking. To address these knowledge gaps, the objective of this study was to characterize the activities of a variety of nitrogen and phosphorus acquiring enzymes on the roots of a diverse range of native and invasive exotic plants. High rates of phosphatase and chitinase activity were observed on the roots of all plant sampled compared to the surrounding soil. Rates of root phosphatase activity were the highest ever recorded in our laboratory, even exceeding rates of 14,000 nmol/h/g on roots of the non-mycorrhizal invasive herb Alliaria petiolata (garlic mustard). Roots were also examined for two types of peptidases, leucine amino peptidase and glycine amino peptidase. No roots had any significant glycine amino peptidase activity, while a small proportion exhibited relatively low rates of leucine amino peptidase activity. Regressions comparing nutrient levels and enzyme activity showed no significance, but a few significant relationships were observed with the plants Lonicera maackii (honeysuckle), Acer rubrum (red maple), and A. petiolata. Comparing invasive exotic and native plants yielded no significant comparisons save that A. petiolata again had significantly higher leucine amino peptidase and phosphatase activity than (open full item for complete abstract)

Committee: Michael Weintraub (Advisor); Elliot Tramer (Committee Member); Scott Leisner (Committee Member) Subjects: Botany; Ecology; Environmental Science

Doctor of Philosophy, The Ohio State University, 2024, Chemistry

My dissertation research develops Raman spectroscopy-based sensors to measure aspects of human and plant health or disease states at the point of need, specifically in areas where current sensing methods are insufficient. The first main project area involves monitoring plant health, specifically soil ecology, in real time without harvesting the plant. Sensors are needed to non-invasively observe chemical changes expressed in plant leaves which result from nutrition conditions in the soil. These sensors would be especially useful to inform fertilization practices, increasing efficiency and sustainability. The second major project area focuses on developing a rapid and accurate diagnostic assay for COVID-19. The limitations of established testing methods, such as at-home antigen tests and polymerase chain reaction (PCR) assays, motivate the exploration of alternative techniques that do not sacrifice accuracy for speed. To tackle these sensing challenges, my research employs Raman spectroscopy, which uses light to probe the molecular composition of a sample. Each molecule has a unique Raman signature, and Raman signal is proportional to the concentration of molecules present in the sample, making the technique highly advantageous for identification and quantification. Raman signals can be collected quickly and non-destructively with minimal sample preparation. To detect low concentrations of analytes or poorly scattering analytes, we use surface enhanced Raman spectroscopy (SERS), a technique in which metal nanostructures amplify the Raman signals of the molecules near the nanostructures. Overall, this dissertation work focuses on optimizing portable Raman and SERS methods to non-invasively assess plant health and to detect COVID, all in a matter of seconds. Chapter 1 introduces the background and motivation for these projects, as well as the analytical techniques used to address them. Chapter 2 describes the development of handheld Raman techniques to monitor th (open full item for complete abstract)

Committee: Zachary Schultz (Advisor) Subjects: Analytical Chemistry; Chemistry

Master of Science (MS), Wright State University, 2023, Biological Sciences

Invasive species threaten ecosystems and economies. Globally, biological invasions are estimated to have cost over $2.1 trillion since 1970. In Eastern North American woodlands, invasive plants are rapidly displacing natives. This is concerning, because invasive plants may not support the diverse and abundant arthropod communities essential to ecosystem function. Despite the conceptual understanding of invasive shrubs' potential to transform forest communities, scant research has focused on the effect of invasive plants on higher trophic levels here in Ohio. To address this gap, I examined the diversity and abundance of arthropod communities, caterpillar performance, and caterpillar predation on two invasive shrubs, Amur honeysuckle (Lonicera maackii) and border privet (Ligustrum obtusifolium), relative to native counterparts. Lo. maackii supported a depauperate community; however, Li. obtusifolium hosted a surprisingly robust community. Nevertheless, both invasives proved poor hosts for caterpillars and were less preferred by foraging insectivores.

Committee: John O. Stireman III, Ph.D. (Advisor); Don Cipollini Jr., Ph.D. (Committee Member); Volker Bahn Ph.D. (Committee Member) Subjects: Biology; Ecology; Entomology; Environmental Science; Plant Sciences; Zoology

Doctor of Philosophy, The Ohio State University, 2021, Evolution, Ecology and Organismal Biology

Humans engineer their environments by transporting species around the planet. In a new environment, most introduced species will perish, but a small proportion can become invasive, spreading widely and impacting their environments. My dissertation explores how evolutionary processes shape invasive species. I studied two mechanisms of invasive species evolution that can induce rapid evolutionary change: hybridization (mating between genetically distinct individuals) and whole genome duplication (WGD, when offspring inherit an extra set of chromosome pairs). In Chapters 1 and 2, I describe experiments with members of the model plant genus Arabidopsis differing only in genome size and status as either parent or hybrid, effectively isolating the independent effects of WGD and hybridization on traits. I grew plants together under controlled conditions and measured traits and phenotypic plasticity (the change in trait values across imposed environmental gradients). For the handful of traits and gradients in which WGD shifted plasticity values, WGD consistently increased plasticity (Chapter 1). This study provides the most controlled experimental evidence to date in support of the hypothesis that WGD increases plasticity, a hypothesis invoked to help explain how WGD has driven evolution. In contrast to WGD, I found that hybridization produced larger effects on both mean traits and plasticity (Chapter 2). This experiment is the first to fully isolate hybridization and WGD effects on plasticity. In nature, genetic and trait variation provide the raw material allowing invasive species to initially prevail in and, potentially, adapt to the introduced environment. I examined patterns of variation related to hybridization and WGD for two invasive plant systems (Chapters 3 and 4). Chapter 3 focuses on purple loosestrife (Lythrum salicaria), a well-studied species for which other authors have documented post-introduction changes in traits and genetics. A little-studied, mo (open full item for complete abstract)

Committee: Stephen Hovick (Advisor); Alison Bennett (Committee Member); Andrea Wolfe (Committee Member); Kristin Mercer (Committee Member); Amanda Simcox (Committee Member); Robert Klips (Committee Member) Subjects: Biology; Botany; Conservation; Ecology; Evolution and Development; Genetics; Horticulture; Morphology; Organismal Biology

Master of Science (MS), Ohio University, 2020, Environmental Studies (Voinovich)

This study investigated pollinator use across areas of the channelized Hocking River's banks in different stages of ecological succession, according to when each area last experienced a mowing disturbance. These successional stages of growth—an associated pollinator use—were compared according to each area's community structure using metrics such as diversity, leaf area index (LAI), greatest height, percentage of native plants, and percentage of noxious plants. Each successional stage was monitored over time to assess seasonal change in both vegetative growth and pollinator use. Each area was also evaluated for both actual and hypothetical roughness scenarios to determine what impact mowing regimes—and lack thereof—might have on flood potential. Considerations were given to past studies that examined community perceptions of the channelized river, as well as precipitation and flood trends. Ultimately, this study investigated whether alternative mowing practices could be socially, economically, and ecologically beneficial, without jeopardizing flood protection. The study concluded that the ecosystem service benefits of actively managed growth outweigh the risk of flooding in the channel. It recommends that further studies, including a review from the Army Corps of Engineers, be undertaken to begin the process of restoring the channelized Hocking River's riparian zone to a more sustainable and ecologically beneficial state.

Committee: Natalie Kruse Daniels Ph.D. (Advisor); Rebecca Snell Ph.D. (Committee Member); Amy Lynch Ph.D. (Committee Member) Subjects: Biology; Botany; Civil Engineering; Conservation; Ecology; Engineering; Entomology; Environmental Management; Environmental Science; Environmental Studies; Geography; History; Horticulture; Hydrologic Sciences; Hydrology; Landscape Architecture; Management; Plant Biology; Plant Sciences; Pollen; Wildlife Conservation; Wildlife Management

Bachelor of Science, Ashland University, 2019, Biology/Toxicology

This study observed differences in the quality of two marshes' plant communities at the Black Fork Wetlands Preserve to monitor potential changes in plant community structure due to invasive reed canary grass, Phalaris arundinacea. Two threatened bird species (Rallus limicola and Porzana carolina rails), preferring a blend of woody and emergent vegetation, have been repeatedly observed at a native plant marsh but only once at a P. arundinacea-dominated boardwalk marsh potentially due to differences in plant community structure. Species richness, evenness, and abundance was quantified at each site and biomass data collected for Sparganium androcladum, Carex camosa, Typhus latifolia along with P. arundinacea. Plant identifications were used to calculate the Floristic Quality Assessment Index and Simpson's Index as a measure of quality for each marsh. Aerial images were used to map the boardwalk site and measure percent cover of P. arundinacea. Percent cover was estimated to be 40%. The boardwalk marsh had less diversity than the rail marsh; approximately 90% of the vegetation sampled in the boardwalk marsh was P. arundinacea while S. androcladum at the rail marsh ranged from 20-70% across the areas of the transect. P. arundinacea had up to three times as much biomass as S. androcladum, indicating a denser community. The boardwalk marsh lacked woody vegetation within sampling plots while the rail marsh had both Cornus stolonifera and Salix nigra. Differences in the vegetation present and their differing distributions as a result of P. arundinacea growth may impact habitat suitability for fauna such as threatened rails.

Committee: Patricia Saunders Dr. (Advisor); Dolly Crawford Dr. (Advisor); Merril Tawse (Advisor) Subjects: Biology; Botany

Master of Science (MS), Bowling Green State University, 2019, Geology

The application of remote sensing techniques in mapping, classifying and monitoring land cover, land use and vegetation are popular among the researchers and scientists for several decades. It became more productive and economical in recent years with the advancement of information technology in a sophisticated and revolutionary manner. Currently, remote sensing is a widely used effective technique that provides spatial and temporal information about vegetation and invasive species in wetlands. The first objective of this study was to assess the effectiveness of the data obtained via Unmanned Ariel Vehicles (UAV) to identify invasive Phragmites australis in the Old Woman Creek (OWC) in Ohio. Secondly, the study aimed to determine the most suitable algorithm to distinguish between Phragmites australis and other vegetation types using pixel based and object based classification methods and a combination of feature layers derived from the UAV images. Pixel based classification found to be performing better than object based classification. Pixel based Neural Network (NN) was identified as the best classifier to map Phragmites in OWC with the least error of omission of 1.59% and the overall accuracy of 94.80% based on the Sequoia image acquired in August that was stacked with Canopy Height Model (CHM) from August and NDVI, which was derived using UAV data acquired in October (NDVIOct). The study emphasizes the necessity of a suitable sampling method and the use of optimum parameters of non-parametric classifiers. The study provides future directions for data acquisition to map Phrgamites at early and mid-summer to find data to eradicate Phragmites effectively in OWC estuary.

Committee: Anita Simic Milas Ph.D. (Advisor); Andrew Gregory Ph.D. (Committee Member); Angelica Vazquez-Ortega Ph.D. (Committee Member) Subjects: Ecology; Environmental Science; Geography; Remote Sensing

Master of Science in Botany, Miami University, 2018, Biology

In the fragmented forests of Ohio, native tree recruitment has been reduced by abundant white-tailed deer and invasion of Amur honeysuckle (Lonicera maackii). While shrubs compete with tree seedlings, live shrubs can facilitate growth and survival of native tree seedlings in the presence of deer. It is less clear if dead shrubs can have this same effect. In this study, I tested the hypothesis that dead L. maackii shrubs provide refuge for native tree seedlings from deer browse and facilitate growth and survival. In the Miami University Natural Areas in Oxford, OH, I planted 512 native tree seedlings within plots comparing controls to three different L. maackii removal strategies: complete shrub removal, felling of shrubs leaving branches on the ground, and basal bark herbicide application. I found that dead branches in the Felling treatment provided refuge from browse and facilitated growth and survival for Carpinus caroliniana, but did not facilitate growth and survival for Quercus alba, Celtis occidentalis, or naturally occurring seedlings. This result partially supports the hypothesis that dead L. maackii branches facilitate growth and survival of native tree species, but demonstrates that the effect varies among tree species and may be dependent on deer browse preference.

Committee: David Gorchov Dr. (Advisor); Melany Fisk Dr. (Committee Member); Thomas Crist Dr. (Committee Member) Subjects: Biology; Botany; Ecology; Natural Resource Management

Doctor of Philosophy (PhD), Wright State University, 2018, Environmental Sciences PhD

The invasion of novel habitats by non-native plant species is a worldwide problem with serious economical and ecological implications. Broad biotic and abiotic filters contribute to the overall invasibility of non-native species. Invasive plants have the ability to rapidly establish themselves and outcompete their native counterparts as result of their relationship with herbivorous arthropods. Because invasive plants displace native plants, reduce overall plant diversity, and alter vegetation structure, this can have cascading effects on insect herbivores, particularly those that rely on one or a few food plants, and arthropod predators. The genus Euonymus (Celastraceae) is comprised of 130 species. Euonymus alatus (burning bush) and Euonymus europaeus (spindle tree) are two non-natives that have been introduced to North American. Although these species are recognized as invasive in portions of the United States, very little is known about their invasion status, relationship with native herbivores, or community impacts. We sought to fill these gaps with a particular focus on burning bush. We first investigated the distribution of burning bush in Ohio and biotic and abiotic factors that contribute to its success through a citizen science self-reporting protocol. We then examined the relationship of burning bush and spindle tree to herbivorous arthropods through examining field herbivory, success in no-choice bioassays, and analysis of chemical defenses. Finally, we examined the cascading impacts of burning bush and overabundant deer on environmental characteristics and arthropod communities. Euonymus alatus was present across Ohio but more likely to be successful in locations with greater disturbance and resources. Burning bush and spindle tree are likely experiencing enemy release as both receive significantly less herbivory than a native congener. While both burning bush and spindle tree contained elevated levels of secondary metabolites, a generalist herbivore (open full item for complete abstract)

Committee: Don Cipollini Ph.D. (Advisor); Mary Gardiner Ph.D. (Committee Member); Thomas Rooney Ph.D. (Committee Member); John Stireman III Ph.D. (Committee Member); Thaddeus Tarpey Ph.D. (Committee Member) Subjects: Biology; Conservation; Ecology; Entomology; Environmental Science; Plant Biology

Master of Science, Miami University, 2017, Botany

Selectivity by overabundant, generalist herbivores leads to intensive browsing on preferred species, which may allow less-preferred invasive species to flourish. Recent work from our lab indicated that an invasive shrub (Lonicera maackii) comprises a large proportion of deer diet in Miami University Natural Areas, but this may reflect high frequency of L. maackii rather than preference. I tested three hypotheses: (1) Deer prefer to browse on L. maackii versus other woody plants, (2) L. maackii is not a preferred source of browse, but consumed when alternative foods are depleted or (3) L. maackii is a unique food resource for deer, e.g. a nutritious food during a season of scarcity. We assessed preference for L. maackii and co-occurring woody plants across 8 sites in southwest Ohio by counting browsed and unbrowsed twigs of each species and calculated an electivity index.L. maackii electivity was negative at most sites, indicating it is not preferred, but lack of support for a negative trend between L. maackii browse and more-preferred twig densities indicates it is not strictly low preference. A negative trend betweenL. maackiibrowse and L. maackii density supports the importance of L. maackii as a source of browse during early spring.

Committee: David Gorchov (Advisor); Richard Moore (Committee Member); Thomas Crist (Committee Member) Subjects: Ecology; Plant Sciences

Master of Science (MS), Wright State University, 2016, Biological Sciences

The purpose of this study was to investigate novel interactions of native herbivores (Abia inflata, Abia americana, Zaschizonyx montana, and Hyphantria cunea) with non-native plants in Ohio. No-choice and choice bioassays were conducted with adults and larvae to examine life history traits, performance, and preference of these herbivores feeding exclusively on native and non-native species and damaged and undamaged foliage. It was found that all organisms in this study can perform well and complete their whole life cycle on L. maackii. Adult A. americana will oviposit in non-native hosts however newly emerged larvae have 100% larval mortality on L. japonica. A. inflata had a reduction in larval mass on herbivore damaged foliage but not artificially damaged foliage. Some non-native species (L. maackii, L. tatarica and P. calleryana) appear to be suitable host for H. cunea, whereas other non-native species (L. japonica, E. alatus, and E. umbellata) are unsuitable hosts for early larval development. When given a choice H. cunea caterpillars preferred native foliage. These studies could benefit efforts at using these native insects as biocontrol agents for L. maackii or other non-native, invaders.

Committee: Don Cipollini Ph.D. (Advisor); John Stireman Ph.D. (Committee Member); Thomas Rooney Ph.D. (Committee Member) Subjects: Biology; Ecology; Environmental Science

Master of Science (MS), Bowling Green State University, 2014, Biological Sciences

Invasive plants impact amphibians by altering habitat, predator-prey interactions, and reproductive sites. Despite being costly and having serious non-target impacts to wildlife, chemical management is the most common method to reduce or eliminate invasive plants. In spite of previous studies indicating that individual effects of invasive plants or pesticides can be harmful to amphibian populations, the impact of the interaction between invasive plants and herbicide management on amphibians has not yet been evaluated. In Chapter I, a controlled laboratory experiment was performed to assess the impact of the invasive aquatic plant Eurasian watermilfoil (Myriophyllum spicatum), the terrestrial invasive European buckthorn (Rhamnus cathartica), the herbicide triclopyr and the combination of invasive plant leachate and herbicide on the growth, morphology and survival of northern leopard frog (Lithobates pipiens) tadpoles. Tadpoles were raised in treatments groups for a number of weeks, after which treatment additions were stopped in order to assess for lag effects. Multiple factors including habitat loss/modification, pollutants, invasive species, and disease have contributed to the global decline of amphibians and declines in their abundance are expected to continue due to changes in climate. Climate change is expected to cause range expansion of many invasive plants; therefore, the use of chemicals to manage invasive plants may increase. Chapter II examined the effects of the invasive plant European buckthorn (Rhamnus cathartica), the herbicide triclopyr, and increased temperature on the on the survival, behavior, growth and morphology of Northern leopard frog (Lithobates pipiens) tadpoles. Results from this study encourage further examination of the effect of chemical management, but more importantly the potential impacts of climate change on declining amphibian populations.

Committee: M. Gabriela Bidart-Bouzat Ph.D. (Advisor); Karen Root Ph.D. (Committee Member); Daniel Wiegmann Ph.D. (Committee Member) Subjects: Aquatic Sciences; Biology; Climate Change; Conservation; Ecology; Freshwater Ecology; Toxicology

Bachelor of Arts (BA), Ohio University, 2014, Environmental Studies

Reclaimed mine lands account for high portions of land within southeastern Ohio, and fully restoring these lands to their original state requires much time and effort. The legal requirements for reclamation are minimal, and restoration and land management after reclamation is ideal when financially possible. Reclamation aims to promote drainage, prevent acid production and establish vegetative cover, while post-reclamation restoration and management aims control invasive plants, prevent erosion, and aid in returning a disturbed habitat to its original condition. The objective of this study is to compare species richness, vegetation diversity, proportion of native to invasive plants, and percent organic matter between reclaimed mine lands that have experienced post-reclamation management, including further plantings, invasive removal, grazing, or burning, and reclaimed mine lands that have not been managed after an initial vegetative cover was established. Vegetation composition was assessed at 42 sites (21 managed and 21 unmanaged sites) using the North Carolina Vegetation Survey method. The results found that cover of native plants was not significantly different between managed and unmanaged sites, but the cover of invasive plants was significantly greater in unmanaged sites. The occurrence of invasive species correlates to the success of a site because invasive plants benefit from disturbance. The vegetation diversity and species richness was higher in managed sites. There was a significant difference between organic matter in managed and unmanaged sites. Post-reclamation management allows a site to be more successful by creating higher diversity and therefore a better ability to adapt to change or disturbance.

Committee: Natalie Kruse (Advisor) Subjects: Botany; Environmental Science; Environmental Studies; Plant Biology

Master of Science, Miami University, 2014, Botany

The objectives of my study were (1) to determine the spatial distribution of four invasive species; Rubus phoenicolasius, Berberis thunbergii, Rosa multiflora, and Lonicera japonica in a mature forest; (2) to investigate the role of propagule rain from a road, logged forest, and floodplain on these distributions, and (3) to explore the role of treefall gaps as a facilitator of invasion. The importance of propagule rain was indicated by higher densities of R. multiflora near the floodplain and R. phoenicolasius and climbing L. japonica near the road. Based on higher frequency and density, gaps are important for the establishment, growth, and reproduction of R. phoenicolasius, growth of R. multiflora and L. japonica, and reproduction of B. thunbergii.

Committee: David Gorchov PhD (Advisor); Thomas Crist PhD (Committee Member); M. Henry H. Stevens PhD (Committee Member); Jing Zhang PhD (Committee Member); Ziying Jiang PhD (Committee Member) Subjects: Botany; Ecology; Geographic Information Science

Master of Science, Miami University, 2014, Botany

Long-distance seed dispersal contributes to the spread of invasive plants. Identification of seed dispersal vectors will help manage the spread of invasive plants, such as Lonicera maackii, a common invasive shrub in Ohio. Several bird species are dispersal vectors of L. maackii, but recent evidence suggests that deer may also contribute. I found that deer browse on L. maackii while fruits were ripe, but did not prefer fruiting branches. Male deer were projected to disperse a greater proportion of seeds over long distances than female deer. I found no evidence of deer dispersal of L. maackii seeds along an invasion front, but 31% of deer pellet groups collected in an invaded area contained germinable L. maackii seeds. I conclude that deer are important long-distance seed dispersal vectors of L. maackii, and suggest that land managers interested in eradicating this invasive shrub reduce the number of male deer in local herds.

Committee: David Gorchov Dr. (Advisor); Thomas Crist Dr. (Committee Member); Hank Stevens Dr. (Committee Member) Subjects: Botany; Ecology

Bachelor of Science (BS), Ohio University, 2014, Environmental and Plant Biology

Reclaimed mine lands account for high portions of land within southeastern Ohio, and fully restoring these lands to their original state requires much time and effort. The legal requirements for reclamation are minimal, and restoration and land management after reclamation is ideal when financially possible. Reclamation aims to promote drainage, prevent acid production and establish vegetative cover, while post-reclamation restoration and management aims control invasive plants, prevent erosion, and aid in returning a disturbed habitat to its original condition. The objective of this study is to compare species richness, vegetation diversity, proportion of native to invasive plants, and percent organic matter between reclaimed mine lands that have experienced post-reclamation management, including further plantings, invasive removal, grazing, or burning, and reclaimed mine lands that have not been managed after an initial vegetative cover was established. Vegetation composition was assessed at 42 sites (21 managed and 21 unmanaged sites) using the North Carolina Vegetation Survey method. The results found that cover of native plants was not significantly different between managed and unmanaged sites, but the cover of invasive plants was significantly greater in unmanaged sites. The occurrence of invasive species correlates to the success of a site because invasive plants benefit from disturbance. The vegetation diversity and species richness was higher in managed sites. There was a significant difference between organic matter in managed and unmanaged sites. Post-reclamation management allows a site to be more successful by creating higher diversity and therefore a better ability to adapt to change or disturbance.

Committee: Natalie Kruse (Advisor) Subjects: Environmental Science; Environmental Studies; Plant Biology

PHD, Kent State University, 2013, College of Arts and Sciences / Department of Biological Sciences

Regula, Lis Kenneth., Ph.D., December 2013 BIOLOGY INVASIVE PLANTS AND NATIVE AMPHIBIANS: THE IMPLICATIONS FOR AMPHIBIAN CONSERVATION IN EASTERN NORTH AMERICA (247 PP.) Adviser of Dissertation: Oscar Rocha and Mark Kershner Humans introduce non-native plants to new areas at an increasing rate with the increased movement across the globe. These invasive species can become mono-cultures and extremely different from the native floral community. Amphibians, at the same time, are facing global declines with approximately one-third of all amphibians threatened or endangered. Due to the importance of amphibians as prey items for many vertebrates including small birds, mammals, and reptiles, and also predator controls over many invertebrates, including some pest species, the decline of amphibians has large implications for many environments. This study looks at a range of interactions between two invasive plants (Typha angustifolia and Phragmites australis) and two native anurans (Lithobates clamitans and Lithobates catesbeianus). As ecosystem engineers, plants form the basis of many communities, and sculpt the physical environment by adding complexity to the earth's surface. They also add chemical constituents either actively or passively too ward off other competitors. This change in the environment on both the chemical and physical level leads to complex possibilities for a changed plant community to impact the rest of the ecosystem, including amphibians. I focus on the physical changes by looking at behavior of amphibians in these invasive plant mono-cultures and non-invaded controls, and their appearance in invaded and non-invaded wetlands, both constructed and naturally occurring. On the chemical side of the matter, I monitor water chemistry measures in natural and constructed wetlands that are either lacking invasive plants or have a substantial presence of these plants, and correlate those measures with tadpole growth and survival.

Committee: Oscar Rocha PhD (Advisor); Mark Kershner PhD (Advisor) Subjects: Biology; Ecology

MS, University of Cincinnati, 2013, Arts and Sciences: Biological Sciences

Invasive plant species can lead to reduced biodiversity and are expensive to control. Ornamental gardening has played a key role in introducing nonnative species into new areas where they may become invasive. This study investigated the role of ornamental gardening along an urban-rural gradient as a pathway for introducing nonnative plant species to forests in Southwestern Ohio. Vegetation surveys were conducted in 15 forests, and patterns of nonnative species richness were analyzed. To better understand which nonnative plant species should be considered invasive, two invasive plant risk assessments were used. Results indicated that the ornamental gardening pathway has been important in introducing invasive species along the entire urban-rural gradient, but the prominence of the ornamental pathway in introducing nonnative species was stronger in rural areas compared to urban areas. The two risk assessments used, the Australian Weed Risk Assessment and the Ohio Invasive Plant Assessment, indicated that 18 of the 39 nonnative plant species documented during the forest vegetation surveys should be considered invasion risks, 14 of which species had ornamental origins. This project suggests that engaging gardeners and professional horticulturalists in sustainable gardening practices could be one of the most efficient ways to reduce the number of nonnative plant species from entering natural areas. More research concerning the social and behavioral aspects involved in introducing invasive plants with ornamental origins could provide important information that would enable meaningful education and outreach.

Committee: Theresa Culley Ph.D. (Committee Chair); Sarena Selbo M.S. (Committee Member); Steven Rogstad Ph.D. (Committee Member) Subjects: Ecology

Doctor of Philosophy (PhD), Wright State University, 2008, Environmental Sciences PhD

Garlic mustard (GM), Alliaria petiolata, a European biennial herb invasive in North America, produces secondary metabolites that may contribute to its invasive success by allelopathically inhibiting growth of native plants. I tested this hypothesis by determining the levels, and stability, of these compounds in field soils. I also explored differences in the phytochemical profiles of GM and closely related North American species, and biogeographic differences in allelopathic effects on North American and European arbuscular mycorrhizal fungi (AMF). Furthermore, I exposed a North American annual herb, pale jewelweed (Impatiens pallida), and its AMF, to GM extracts in order to determine how GM metabolites interact to inhibit growth throughout the formation of mycorrhizal symbioses. Additionally, I determined whether or not allelopathic inhibition remained significant when resource competition was also occurring, by exposing jewelweed plants grown at various densities to GM extracts. Also, I assessed allelopathic effects on AMF diversity by performing terminal restriction fragment length polymorphism analysis on AMF DNA isolated from field soils collected either in or outside of GM populations. Finally, I explored how three methods commonly used to kill GM influenced the health of jewelweed plants later planted in the same soil. Secondary metabolites produced by GM decompose too quickly to account for long term inhibition, suggesting that degradates of these compounds are bioactive. None of the compounds produced by GM were found in four North American species, and North American AMF were more sensitive to allelopathic effects than European AMF. I found strong inhibition of seed germination and growth of uncolonized plants, but AMF appeared to protect colonized jewelweed plants from any allelopathic effects. Allelopathic effects were not as significant as effects of resource competition on jewelweed plant size. AMF diversity was lower in sites with GM than without. Du (open full item for complete abstract)

Committee: Don Cipollini PhD (Advisor); James Amon PhD (Committee Member); Wayne Carmichael PhD (Committee Member); Carl Friese PhD (Committee Member); Chris Barton PhD (Committee Member) Subjects: Biology; Botany; Ecology; Microbiology

Doctor of Philosophy, The Ohio State University, 2012, Horticulture and Crop Science

Invasions by exotic insect pests and pathogens have been devastating North American forests for decades. Presently, emerald ash borer (EAB; Agrilus planipennis) is devastating populations of native ash (Fraxinus species) trees throughout eastern North America. Disturbances, such as canopy gap formation due to EAB-induced ash mortality, alter availability of resources including light, water, and mineral nutrients, potentially resulting in shifts in plant community composition. Following the loss of nearly all reproductively mature trees, ash regeneration was effectively eliminated, and the “orphaned cohort” of ash in the seedling layer represents the potential for persistence of ash in EAB-impacted forests. Hemispherical photographs, used to calculate percent gap fraction, were taken at a height of 1.5 m to determine how loss of ash was affecting radiant energy resources available to the understory vegetation. Variation among gap fraction values indicated high heterogeneity in light reaching the forest understory. Percent gap fraction was negatively correlated with percent plant cover within the 2 – 5 m and > 5 m layers, suggesting that while gaps may have formed in the canopy layer, light was intercepted before reaching the forest understory. Plant abundance and composition within the forest understory did not change dramatically during the course of the study, nor was there a direct connection between species abundance or diversity and gap fraction. Plant communities were slightly differentiated by the soil hydrological conditions, and less diverse communities occurred in mesic and xeric sites than in hydric sites. Growth of invasive and native species in the understory was not influenced by percent gap fraction; invasive species typically outgrew native species regardless of light level and soil hydrological condition. In a comparison of emergence and survival of Lonicera maackii and Rosa multiflora under various native and invasive leaf litters we found no differ (open full item for complete abstract)

Committee: John Cardina PhD (Advisor); Daniel A. Herms PhD (Committee Member); P. Charles Goebel PhD (Committee Member); Kathleen S. Knight PhD (Committee Member); Emilie E. Regnier PhD (Committee Member) Subjects: Biology; Botany; Conservation; Ecology; Forestry