Master of Science, The Ohio State University, 2020, Environment and Natural Resources

Urbanization can have profound influences shaping patterns of songbird diversity. For many species, urbanization poses considerable challenges, yet in many instances urban areas provide important habitat for songbirds, most notably riparian urban areas. With renewed interest to maintain functioning urban forests, understanding the interactions between songbirds and their urban environments is critical to making informed land management decisions. My research addresses habitat usage of breeding urban songbirds in Columbus, Ohio, focusing on the relationship between urban songbird presence and behavior and the vegetation in urban riparian forests. Previous songbird studies have been conducted in the Columbus metropolitan area since 2001 and have focused primarily on the impacts of urbanization on abundance, nesting, and survival. My goals for this study were to add to this knowledge base by examining potential correlations between songbird territory density and structural vegetative characteristics in urban forests and to investigate the foraging strategies of urban songbirds. The first component of my study examines the relationship between the breeding territory densities of individual songbird species and the vegetation structure of urban sites. Given that vegetation structure has been linked to urban songbird abundance and survival, the number of trees, the size of trees, and the density of exotic or native stems in a site may influence the territory density of certain species. I tested the hypotheses that overall songbird territory density will be greater in areas will fewer exotic stems and Neotropical territory density will increase with structural diversity. I conducted spot maps in urban riparian forests in Columbus, Ohio from late April to August in 2019 and compared these data to spot maps conducted by my colleagues in 2007 and 2011 to determine territory densities for the most common species, which included the Blue-gray Gnatcatcher, Blue Jay, Carolina (open full item for complete abstract)

Committee: Stephen Matthews PhD (Advisor); G. Matthew Davies PhD (Committee Member); Charles Flower PhD (Committee Member); Christopher Tonra PhD (Committee Member) Subjects: Urban Forestry; Wildlife Conservation; Wildlife Management

PhD, University of Cincinnati, 2004, Arts and Sciences : Biological Sciences

Ecological restoration of hazardous waste sites is a potential remediation strategy that has not been well documented. Here, we assessed natural plant community development and soil remediation on an aged petroleum refinery land treatment unit (LTU) containing recalcitrant environmental pollutants. Preliminary assessment of phytotoxicity using bioassays (Lactuca sativa L. and Solidago canadensis L.) indicated that some tolerant phenotypes would grow on LTU soil. Fourteen permanent plots (37 m²) were then established onsite to assess actual plant succession and remediation: 11 for study of natural succession and 3 to act as a control by removal of vegetation. Two soil cores were removed annually from each plot, analyzed for edaphic factors and then sequentially extracted for metals and PAHs. Analysis of contaminants indicated a 50% reduction of total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) in surface soil of vegetated and unvegetated plots after three years. There were no significant changes in total metal loadings. Metal content in plant root and shoot tissue was highly variable between species, but still low relative to soil levels, verifying the low bioavailability estimated from soil extracts. Plots were subsampled (1 m²) monthly for cover and abundance during the growing season, and for biomass at the end of the season. Monthly measurements of plant variables indicated that species richness increased from 28 to 57 species, cover increased from 33 to 79%, and biomass increased by a factor of four over three years. Plant growth was correlated to spatial and microclimatic factors, but contaminant loading showed no correlation. In fall of the following year, both LTU and a nearby unpolluted plant community of comparable size and successional stage were sampled as before: cover and abundance were measured in triplicate subplots (1 m²) within eleven plots. There were no significant differences in richness and percent cover between the (open full item for complete abstract)

Committee: Dr. Jodi Shann (Advisor) Subjects:

Master of Science, University of Toledo, 2009, Biology (Ecology)

Recent studies have shown that exotic plant species can have wide-ranging effects on soil ecosystem processes and biotic diversity, and those effects may be more extensive than previously thought. Garlic mustard [Allliaria petiolata (M. Bieb.) Cavara and Grande] is an exotic, invasive herb that poses a threat to North American forests by reducing native plant performance and recruitment. However, little is known about potential impacts to belowground communities and processes. The object of this study was to determine the effects of A. petiolata on soil physical, chemical, biogeochemical, and biotic properties. Soil samples were collected between October 2006 and February 2008 from plots with A. petiolata present or absent in three Ohio forests: the University of Toledo Stranahan Arboretum (Arboretum), Fuller Preserve (Fuller), and South Park (South). Variables measured included moisture content, pH, organic matter (SOM), nutrient dynamics [dissolved organic carbon (DOC), microbial biomass carbon (Cmic), dissolved organic nitrogen (DON), microbial biomass nitrogen (Nmic), ammonium, nitrate, and phosphate], microbial community function [activities of acid phosphatase (PHOS), α-glucosidase (AG), β-glucosidase (BG), N-acetyl-β-glucosaminidase (NAG), β-D-cellobiohydrase (CBH), β-xylosidase (BXYL), leucine amino peptidase (LAP), urease, phenol oxidase (phenox), and peroxidase (perox)], and microbial community structure [community DNA profiles, Simpson index (D), Shannon index (H'), and richness (S)]. Results showed that A. petiolata presence had a significant affect on only approximately one third of the measured variables. Generally, the variables affected and the direction of effects (positive or negative) were inconsistent both spatially and temporally. Soil moisture, SOM, Nmic, DOC, phosphate, BG activity, ratio of C- to P-acquiring enzyme activities (C:P), and bacterial richness and diversity were lower with A. petiolata present at Arboretum, but most treatment diff (open full item for complete abstract)

Committee: Daryl Moorhead PhD (Advisor); Michael Weintraub PhD (Advisor); William Von Sigler PhD (Committee Member) Subjects: Biology; Ecology; Environmental Science

Bachelor of Science, Wittenberg University, 2023, Biology

This study investigates the soil quality and plant diversity of a discontinued golf course in Springfield, Ohio, with the aim of assessing its potential for restoration. Led by the National Trail Parks & Recreation District, the restoration plans for Snyder Park include the establishment of wet meadows, prairies, and woodlands, which can thrive in the natural hydric soils of the former golf course. In this study, baseline soil data was collected using GIS and GPS technologies, analyzing soil texture, carbon content, nitrate nitrogen, phosphorous, potassium, replaceable calcium, humus, and pH. Plant diversity was evaluated through random sampling of quadrats. Initial observations revealed patches dominated by specific plant species, and a comparison of soil and plant characteristics across elevations was conducted. The golf course mainly consisted of the Westland soil series, which supports water retention. However, deficiencies in humus and low levels of potassium and nitrate nitrogen pose challenges for restoration. Limited native plant species adapted to moist conditions were observed, suggesting ongoing recovery from intensive land management. To sustain a natural wetland or floodplain ecosystem, restoration efforts should focus on introducing native wetland species and providing nutrient inputs, mainly nitrogen and potassium. The Snyder Park golf course holds potential for restoration, but additional measures are necessary for a successful habitat transition.

Committee: John Ritter (Advisor); Nona Moskowitz (Committee Member); Matthew Collier (Committee Member) Subjects: Ecology; Environmental Science; Environmental Studies; Horticulture; Soil Sciences

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

Master of Science in Botany, Miami University, 2022, Biology

Direct effects of white-tailed deer (Odocoileus virginianus) and the invasive shrub Lonicera maackii on woody vegetation are well documented, but studies exploring their long-term interactive effects are limited. I investigated effects after 11 years of deer exclusion or access and L. maackii removal or presence on woody vegetation responses in the Miami University Natural Areas in Oxford, Ohio. Deer exclusion resulted in greater tree seedling richness, density, and basal area, native and non-native shrub richness, native vine density and basal area, change in understory tree richness since 2015, and cover at 0.3 m above ground. Deer exclusion also resulted in greater basal area growth of L. maackii shrubs. Lonicera maackii, in contrast, had no direct effects. Deer and L. maackii interactions impacted native tree seedling richness and density, and total vine density. All significant interactions revealed synergy between deer exclusion and L. maackii removal, most likely due to deer reducing L. maackii cover (via herbivory) and therefore mitigating its negative competitive effects on seedlings and vines Therefore, in areas with high deer densities and dense L. maackii stands, I recommend a reduction of both stressors to prevent tree regeneration failure.

Committee: David Gorchov (Advisor); Jonathan Bauer (Committee Member); Thomas Crist (Committee Member) Subjects: Biology; Botany; Ecology

Master of Science (MS), Wright State University, 2022, Biological Sciences

Garlic mustard is an invasive Eurasian biennial spreading in deciduous forests of North America. Garlic mustard plants in Ohio can be infected with a strain of Xanthomonas campestris, the causal agent of black rot disease in brassicas. I examined variation in susceptibility to X. campestris among garlic mustard populations, several native wild species, and agricultural crop varieties. Twenty-four garlic mustard populations were universally susceptible to X. campestris, though disease severity varied. Cardamine concatenata and Cardamine diphylla were susceptible but can phenologically escape infection in the field. Of the 14 agricultural crops tested, three cultivars (Raphanus sativus, Brassica rapa var. Rapa Hakurei, and cv - Brassica oleracea var. capitata) were susceptible to the X. campestris strain that infects garlic mustards. Nutrient availability enhanced disease susceptibility and severity, but light had a limited effect. A survey of 31 garlic mustard populations in Ohio, Kentucky, and Indiana revealed that X. campestris is established throughout a 120 km radial distance from Dayton, Ohio. The strain of X. campestris infecting garlic mustard in the Wright State University woods was identified by sequencing as X. campestris pv. incanae.

Committee: Donald Cipollini Ph.D. (Advisor); John O. Stireman III Ph.D. (Committee Member); Volker Bahn Ph.D. (Committee Member) Subjects: Biology; Botany; Ecology; Plant Biology; Plant Pathology

PHD, Kent State University, 2022, College of Arts and Sciences / Department of Biological Sciences

The eastern redcedar Juniperus virginiana is the most widespread conifer in the eastern United States, and can be found in every state east of the 100th meridian. This tree is encroaching into new habitats and old fields in the western states, as far as Nebraska and South Dakota. J. virginiana can survive and thrive in adverse conditions and extreme environments. We were interested in testing the effects of biotic and abiotic conditions on J. virginiana ecophysiology. We investigated the role of competition and soil substrates in a greenhouse experiment, and in a series of field experiments, we tested a stress-gradient approach on abiotic stress and intraspecific competition, the role of different soil types on local adaptation of two J. virginiana varieties, and the effects of tree size and season on J. virginiana performance and ecophysiology. We found that there was a strong effect of competition with grass (Bromus inermis) but not with post oak (Quercus stellata). In addition, fertilizer had a greater effect than lime on J. virginiana performance, indicating that J. virginiana tolerates rather than prefers limestone soil to avoid competition with other tree competitors. We also found support for Walter's two-layer hypothesis in which there was root partitioning between the J. virginiana and smooth brome grass. Similarly, we also found root partitioning and differentiation between the J. virginiana and post oak, due to root length differences. In our stress-gradient experiment, we found that the population at the site furthest from Lake Erie and with the highest soil nutrients had greater physiological activity and total biomass, which supported our predictions. Intraspecific competition was not an important factor affecting J. virginiana performance. Surprisingly, the intermediate site had the lowest overall performance and lowest water stress, due to poor drainage, indicating that more parameters need to be considered when setting up a stress-gradient experime (open full item for complete abstract)

Committee: David Ward (Advisor); Emily Rauschert (Committee Member); Oscar Rocha (Committee Member); Juliana Medeiros (Advisor) Subjects: Biology; Climate Change; Ecology; Plant Biology; Plant Sciences

Master of Science (MS), Bowling Green State University, 2020, Biological Sciences

Introduced to the Great Lakes Region from Europe before 1900, invasive Butomus umbellatus (Flowering rush) forms monotypic stands that crowd native species and cover open water systems across Great Lakes shorelines and reservoirs in the northern US. Factors contributing to invasion persistence and impacts on ecosystem function by this species are poorly understood. This study characterizes vegetation and environmental factors at the Ottawa National Wildlife Refuge, which borders Lake Erie, to understand how sediment nutrient levels in watersheds affect B. umbellatus invasion. We hypothesized that increased sediment nutrient levels are important drivers of B. umbellatus invasion success. Sediment nutrient levels, matter, water depth, and vegetation were sampled within 1m2 plots throughout the management units of the marsh complex. Vegetation of B. umbellatus and 18 other species present were harvested or canopy characteristics measured to estimate biomass. B. umbellatus was the most abundant of all identified emergent invasive species found, occurring at 55 % of the surveyed plots. B. umbellatus rhizome bud count averaged 509 per plot, with a range of 0 – 2760 buds. While sediment nutrient analysis of nitrogen and phosphorus showed heterogeneity within and across management units, nutrient levels did not predict B. umbellatus abundance. However, B. umbellatus biomass decreased with increasing community biomass. Vegetative propagule production via rhizome buds decreased with increased nutrients and increased community biomass. B. umbellatus was found to have a wide range of nitrogen and phosphorus in leaf tissue, and 2 – 4 times more average phosphorus than all analyzed native species. This data will assist managers in identifying timing and approaches for controlling this invasive species and restoring wetland biodiversity.

Committee: Helen Michaels PhD (Advisor); Andrew Gregory PhD (Committee Member); Kevin McCluney PhD (Committee Member); Angélica Vázquez-Ortega PhD (Committee Member) Subjects: Biology

Doctor of Philosophy, Miami University, 2020, Ecology, Evolution and Environmental Biology

This dissertation examines how an invasive woody plant, Lonicera maackii, temporally and spatially structures native bee communities of forest-edge habitat in agricultural landscapes. In Chapter 1, I measured bee species composition and pollination services ≤200 m from isolated forest patches in response to L. maackii flower removals. Removing flowers released a subset of small-bodied bees and increased pollination services after two years. Pollination services provisioned by large-bodied and generalist bee species (e.g. Bombus spp) increased when nearby plants were adjacent to intact L. maackii flowers. Findings suggest that L. maackii flowers suppress one component of the bee community and attract another to the forest patch that increases usage of the adjacent crop fields. In Chapter 2, I compared two components of the bee community and their responses to L. maackii density, floral resources of the forest patch, and the surrounding landscape. Bees sampled in pan traps were typically small, specialized, and responded to local patch features. Bees sampled in vane traps were larger in body size, social, and responded to landscape composition 3 km from the forest patch. These findings suggest that L. maackii floral resources support weaker foragers within the forest patch as well as larger bees that forage throughout the landscape. Both components of the bee community responded to tree community composition and were vertically stratified in the tree canopy. In Chapter 3, I measured bee diversity and community composition at different vertical strata in response to L. maackii density and flowering period as well as floral resource availability of woody plants. I found that L. maackii supports a component of the vertically stratified bee community which changes interactions with floral resources of the native woody vegetation at different vertical strata. Collectively, my studies demonstrate that L. maackii structures forest-edge bee communities through mechanisms invo (open full item for complete abstract)

Committee: Thomas Crist (Advisor); David Berg (Committee Member); Amelie Davis (Committee Member); David Gorchov (Committee Member); Jign Zhang (Committee Member) Subjects: Agriculture; Biology; Conservation; Ecology

MS, Kent State University, 2019, College of Arts and Sciences / Department of Biological Sciences

Land managers across the Appalachian region have been dissatisfied with the progress of native temperate forest regeneration on surface mines reclaimed under Surface Mining Control and Reclamation Act of 1977 (SMCRA) protocols. These sites are commonly colonized by invasive plant species and have inadequate soils. Many of the nearly 50 former surface mines located within Cuyahoga Valley National Park (CVNP), Ohio, underwent reclamation following SMCRA protocols as an effort to restore native forest habitat, but park staff have also found succession to occur at a far slower rate than originally anticipated. While many studies have been conducted on acidic coal mines, reclaimed sites in CVNP were mined for non-coal resources and are alkaline. Here I investigated the plant communities and soil chemistry of reclaimed surface mines in CVNP to determine the implications of SMCRA protocols on the landscape on sites with alkaline soils. First, I analyzed how vegetative communities on reclaimed surface mines at CVNP changed over a 28-year chronosequence with particular regard to woody species and invasive species. Natural succession of sites was occurring slower than park staff anticipated, as the presence of woody species did not increase significantly over time. However, this did not appear to be a result of invasive plant colonization because exotic plant presence decreased over time, pointing toward inadequate soil conditions rather than interactions among the plant community withholding the growth of woody species. Results imply that SMCRA reclamation protocols do not improve site conditions sufficiently to facilitate natural succession as a tool to return native forests to mines within the timeframe envisioned by land managers. Second, I observed the effects of early colonization of woody nitrogen (N) fixing individuals on soil nutrient concentrations and vegetative communities at the mines. I compared an invasive N-fixing species, autumn olive (Elaeagnus umbel (open full item for complete abstract)

Committee: Chris Blackwood Ph.D. (Advisor); David Ward Ph.D. (Committee Member); Oscar Rocha Ph.D. (Committee Member) Subjects: Ecology

Master of Science, University of Toledo, 2019, Biology (Ecology)

Hydrilla (Hydrilla verticillata), an aquatic invasive plant, threatens to invade the Great Lakes Basin. Hydrilla creates dense webs that out competes native vegetation, reduces flow in canals, clogs intakes, and interferes with navigation of watercraft. Recreational boating has acted as a primary vector of spread for other aquatic invasive species and is expected be a primary vector for hydrilla spread. The goal of this project was to analyze the current distribution of hydrilla and identify the risk of introduction in the Great Lakes Basin via overland recreational boat transport. This goal was achieved by 1) assessing the current distribution of hydrilla to determine likely vectors of spread and 2) predicting the potential spread of hydrilla to the Great Lakes Basin via recreational watercraft and boat trailers and 3) identifying high risk areas for introduction. This analysis will aid in predicting and detecting the spread of invasive hydrilla into new waterways in the Great Lakes Basin.

Committee: Jonathan Bossenbroek PhD (Committee Chair); Richard Becker PhD (Committee Member); Daryl Moorhead PhD (Committee Member) Subjects: Environmental Science

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

PhD, University of Cincinnati, 2014, Arts and Sciences: Biological Sciences

Although the interaction between native and exotic plants and their insect herbivores has been examined extensively, experimental studies on plant responses to generalist insects as well as feeding preferences of generalist insects on native versus exotic plants have provided inconsistent results. This dissertation addresses this issue by incorporating recent methodological recommendations and by exploring interactions between generalist herbivores and native and exotic plants from both the plant and insect perspectives. Using native (Andropogon gerardii and Bouteloua curtipendula) and exotic grasses (Miscanthus sinensis and Bothriochloa ischaemum) with generalist Melanoplus grasshoppers, I combined behavioral and molecular approaches to explore (1) plant resistance and tolerance to grasshopper herbivory, and (2) feeding preferences of Melanoplus grasshoppers for native and exotic plants. Overall, the results from this dissertation project have demonstrated lower resistance of exotic grasses to generalist grasshopper herbivory compared to native grasses; and similar level of plant tolerance to herbivory in native and exotic grasses. Melanoplus grasshoppers demonstrated strong feeding preferences for exotic plants in most of the behavioral experiments and under natural conditions. This suggests that exotic M. sinensis and B. ischaemum grasses with a lack of coevolutionary history with native generalist Melanoplus grasshoppers might have lower physical and chemical defenses than native grasses. Furthermore, generalist Melanoplus grasshoppers may provide biotic resistance to these exotic grasses should they invade natural areas. The results from this dissertation project have important applications for predicting the interaction between exotic plants and generalist herbivores in the introduced range, and if plant invasion has already occurred, for developing effective control plans.

Committee: Theresa Culley Ph.D. (Committee Chair); William Lamp Ph.D. (Committee Member); Joshua Gross Ph.D. (Committee Member); Stephen Matter Ph.D. (Committee Member); George Uetz Ph.D. (Committee Member) Subjects: Biology

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

Master of Science (MS), Wright State University, 2012, Biological Sciences

Plants alter soil characteristics in many ways causing changes in their subsequent growth resulting in either positive or negative feedback on their own fitness. Plants in their native ranges typically experience negative feedback from natural enemies, while feedback is often positive in invaded ranges where they escape enemies, experience new beneficial mutualisms, or bring with them a novel biochemical weapon. I conducted a fully factorial greenhouse experiment to examine plant-soil feedback in the invasive shrub Lonicera maackii and whether or not positive feedback may contribute to its successful invasion in southern Ohio. I also investigated whether the sign and strength of the feedback changed across two distinct soil types, and whether effects were due to shifts in biotic or abiotic soil traits by analyzing soil properties, phenolic content and microbial communities. I compared L. maackii's response to the related native shrub, Diervilla lonicera, using their conditioned soils along with soil conditioned by an unrelated native tree, Fraxinus pennsylvanica. I hypothesized that L. maackii would experience positive feedback overall in both soil types. L. maackii showed positive feedback in Shawnee soils, but neutral to negative feedback in Wright State soils. Growth of L. maackii decreased and positive feedback was eliminated with sterilization in Shawnee soil which may indicate that it had benefitted from mutualisms that were destroyed by sterilization. In Wright State soil, sterilization significantly increased growth, suggesting L. maackii had been released from pathogenic organisms found in live soils. Despite this, feedback became even more negative with sterilization in Wright State soil which may be a sign that its own phytochemicals hinder its growth in the absence of biotic symbioses. Lonicera maackii performed similarly in its own soils and in those of F. pennsylvanica and D. lonicera, regardless of soil type. Our findings also suggest native species a (open full item for complete abstract)

Committee: Don Cipollini PhD (Advisor); James Amon PhD (Committee Member); James Runkle PhD (Committee Member) Subjects: Biochemistry; Biology; Botany; Conservation; Ecology

MS, University of Cincinnati, 2010, Arts and Sciences: Biological Sciences

The exotic shrub Lonicera maackii is a problematic invader of southwestern Ohio forests. As L. maackii invades the forest interior, it negatively impacts native plant diversity and abundance and changes the structure of understory vegetation by replacing the native shrub layer, which has a patchy distribution of plant species, with a dense shrub layer. Changes in diversity or structure of native shrub layer vegetation caused by L. maackii invasion could, in turn, affect associated arthropod fauna. Our objective was to determine whether L. maackii invasion impacted arthropod community composition and structure in the forest shrub layer. We predicted that by negatively affecting the diversity of native plant species in the shrub layer, L. maackii invasion would decrease diversity and abundance of arthropod taxa, trophic groups, and feeding specialists. Alternatively, we predicted that invasion of forests by L. maackii could increase vertical cover of the shrub layer, which could increase diversity and abundance of arthropod taxa, trophic groups, and feeding specialists. We established paired plots in ten forested locations to compare both arthropod community characteristics and characteristics of the shrub layer vegetation between invaded and uninvaded areas. Within paired plots, we captured arthropods from shrub layer vegetation using fumigants and a beating stick and then identified or classified individuals to order and family, trophic group, and specialist/generalist feeder. Additionally, within paired plots, we measured percent vertical cover of shrub layer vegetation with a profile board and identified all individuals of woody shrub layer plants to species. In areas invaded by L. maackii, we found increased or unchanged values of richness and abundance of all arthropod taxa, trophic groups, and specialist feeders. We also observed increased or unchanged values of Shannon's diversity and evenness of all arthropod taxa and trophic groups and relative abundance of (open full item for complete abstract)

Committee: Guy Cameron PhD (Committee Chair); Stephen Matter PhD (Committee Member); George Uetz PhD (Committee Member); Theresa Culley PhD (Committee Member) Subjects: Ecology

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, 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

Master of Science, The Ohio State University, 2012, Horticulture and Crop Science

Invasive plants that spread through natural areas are likely to threaten sensitive and unique habitats. Since it is impossible to kill every individual invasive plant, managers need landscape-scale strategies to direct management efforts along invasion sites and corridors of spread. Therefore, managers need information of how invasive plants spread over time and space with respect to sensitive habitats. Ligustrum vulgare L. (common privet) is a woody invasive plant that is spreading to sensitive habitats in eastern North America. To assist in developing efficient management approaches for this species, we studied the spatial genetic structure of L. vulgare across the landscape within the 325-acre Wooster Memorial Park (WMP) and in three states, using sequences from two chloroplast DNA (cpDNA) genes. For samples taken within the park, we combined patch age, spatial features, and genetic data to reconstruct invasion history and analyze spatial distribution patterns. We conducted a comprehensive survey in the park, mapping and sampling established stands of L. vulgare. Ages of 331 patches in WMP were determined by examining tree-rings. DNA was extracted from samples taken from eight sites in Ohio and two adjacent states along with 313 samples from WMP. Haplotype networks were constructed, and 10 to 17 haplotypes were identified. Haplotype frequencies were geographically different among study sites. Lower genetic diversity was found in the eight Ohio sites compared to sites in New York and Pennsylvania, suggesting an invasion pathway from east to west. In the park, invasion time and three invasion phases were revealed. A similar invasion time and invasion process was observed for all haplotypes. Initial invasion sites were located and their favorable habitats were identified. New establishment and spatial patterns were described through mapping distributions of patches over time. For spatial analyses, we used nearest neighbor analysis, global Moran's I, and local Gi* st (open full item for complete abstract)

Committee: John Cardina PhD (Advisor); Andrew Michel PhD (Committee Member); P. Charles Goebel PhD (Committee Member) Subjects: Horticulture