Doctor of Philosophy (PhD), Ohio University, 2023, Plant Biology (Arts and Sciences)

Global climate change and human management practices are strong external forces that shape the compositions of our forests. My dissertation aimed to determine how these forces are influencing eastern North American forests, specifically focusing critically important, hickories (Carya) and oaks (Quercus). First, the impacts of forest mesophication on hickory populations and broader forest compositions were examined. While long-lived forest overstories remain stable, major compositional shifts in the forest midstory towards mesic-adapted species highlight the speed at which mesophication can alter forests. Next, the impacts of climate variability on hickory were assessed. Among three hickory species (Carya glabra, Carya ovata, and Carya tomentosa), all appear sensitive to summer growing season precipitation and site water balance. However, hickory growth-climate relationships appear to be undergoing a temporal shift to be more important earlier in the growing season. Additionally, the presence of strong growth-climate relationships in understory hickory appears highly-species specific and may indicate valuable species for studying climate impacts on forest understory environments. Finally, the long-term success of sustained forest management practices was evaluated. Hickories and oaks exhibit positive regeneration responses to repeated burning and overstory thinning, although to a varying degree. Overall, my dissertation highlights the potential impacts of climate change and human management on forest ecosystems and the need to recognize and adapt forest research and management to these major forces.

Committee: Brian McCarthy (Advisor); Rebecca Snell (Advisor); Jared DeForest (Committee Member); James Dyer (Committee Member) Subjects: Biology; Climate Change; Ecology; Forestry

Master of Science (M.S.), University of Dayton, 2023, Biology

The structure and composition of forest ecosystems throughout eastern North America has been determined by historical disturbances and successional processes. The white oak group (Leucobalanus) was an important species culturally for Indigenous Peoples of eastern North America for hundreds of years and has been highly valued by European colonizers of the 18th and 19th centuries. The white oak tree (Quercus alba) is a geographically widespread species in eastern North America that has historically been a forest dominant. In addition to popular human uses, Q. alba acorns are an important resource for wildlife. Over the past century, despite being a canopy dominant, Q. alba along with other oaks have exhibited a striking lack of regeneration and recruitment into the canopy across much of its range. This regeneration failure has been associated with a dramatic increase in the importance of shade-tolerant maple species (Acer spp.). A transition from oak-to-maple dominance could have largescale effects on biodiversity, wildlife, and soil characteristics. A variety of explanations for this oak-to-maple dominance shift have been offered in the scientific literature, predominant among these is the multiple interactive drivers hypothesis that asserts historical oak dominance was created by the interaction of multiple disturbance processes. Much remains unknown about the causes of oak-to-maple dominance shift and the multiple drivers hypothesis has not been fully vetted. In this Thesis I sought to examine factors that led to formation of Q. alba dominated forests over the past century by focusing on tree-ring analysis in forests of southwestern Ohio. These forests are near the geographic center of the Q. alba range and are broadly characteristic of the ecology in oak forests of eastern North America. I examined cross section samples of Q. alba (n = 62), chestnut oak (Q. montana) (n = 2), and shagbark hickory (Carya ovata) (n = 1) trees to assess (a) long- (open full item for complete abstract)

Committee: Ryan McEwan (Advisor); Jenn Hellmann (Committee Member); Chelse Prather (Committee Member) Subjects: Biology; Ecology; Environmental Management; Environmental Science

Master of Science in Environmental Science, Cleveland State University, 2021, College of Sciences and Health Professions

Urban forests are increasingly threatened by climate change and the environment of cities. Past dendrochronological studies have focused on more rural ‘natural' forests and has sought to reconstruct past climate regimes and the impacts of drought in these areas. Dendrochronology has begun to expand the urban ecosystem and incorporate traditional ecological principles and functional trait ecology to gain a more thorough understanding of the ecosystems. The confluence of these disciplines, dendroecology, will help guide better understanding of urban forests and aid urban planners and forester in reforestation and afforestation of urban areas. To gain better insight to how species are responding to the urban ecosystem, we analyzed the growth variability of twelve species at Secrest Arboretum and then compared the variability of growth to measures of the climate conditions, functional traits, of phenological characteristics of these species. In May 2019 and June 2020, we extracted increment cores from 59 individuals representing 12 species of commonly planted trees in the Cleveland area from the Shade Tree Evaluation Plot at Secrest Arboretum in Wooster, OH. These increment cores were measured, crossdated, and chronologies of growth were prepared from which we determined the temporal variability of growth. The temporal variability of growth was compared to the climate conditions at Secrest Arboretum. We then compared the temporal variability of growth and climate-growth sensitivity to the functional traits and phenological characteristics of these species. We found evidence that different species exhibit differing variability of growth, that the variability of growth is positively influenced to growth and that unique functional traits and phenological characteristics determine different responses to different climate factors among species.

Committee: Kevin Mueller (Advisor); Emily Rauschert (Committee Member); Julie Wolin (Committee Member); Gregory Wiles (Committee Member) Subjects: Environmental Science

Master of Arts, The Ohio State University, 2019, Geography

The goal of this research is to develop a new proxy record sensitive to water availability in the tropical Andes, where climate change threatens glacial reserves of water stored as ice. As such, this study constitutes the first investigation into the radial growth of the newly described tropical tree species, Polylepis Rodolfo-vasquezii. In the dry season of 2017, a sample set of cores were extracted from a P. rodolfo-vasquezii montane forest in the Cordillera Huaytapallana in the central Peruvian Andes. Standard dendrochronological techniques were applied to the samples to produce a 77 year-long annually resolved chronology, from 1940 to 2016. Correlation analysis between tree ring widths and station data as well as regional anomalies and reveal that P. rodolfo-vasquezii is sensitive to wet season precipitation and discharge from the nearby Shullcas River. The strongest relationship with the tree rings was late wet season discharge. Based on these correlations, the first-ever monthly and seasonal discharge reconstructions were produced for the Shullcas River. The calibration-verification statistics for each model indicate that there are varying degrees of predictive skill in the reconstructions produced. The optimal reconstruction was for the average of April-May discharge. This work provides evidence that Polylepis rodolfo-vasquezii is a useful species for dendrochronological research and highlights its relationship to moisture in the Cordillera Huaytapallana.

Committee: Bryan Mark PhD (Advisor); Alvaro Montenegro PhD (Committee Member); Ellen Mosley-Thompson PhD (Committee Member) Subjects: Environmental Science; Geography; Hydrologic Sciences; Paleoclimate Science

Master of Science (MS), Wright State University, 2018, Biological Sciences

Edge and isolated plant populations provide information about the resilience and the most basic resource needs of a species. Plant demography examines changes in population size and structure over time. An isolated, disjunct eastern hemlock population in Clifton Gorge State Nature Preserve, Yellow Springs, Ohio consists of two distinct subpopulations each with different environmental characteristics, reproductive capacities, and health ratings. Both subpopulations at Clifton Gorge were found to exhibit significant decreases in average annual ring width through time. Linear regression modeling determined that average annual growing season precipitation and temperature were the strongest predictors of these growth trends. A comparative hemlock population at Cantwell Cliffs, Rockbridge, Ohio within the contiguous range of the species displayed environmental characteristics more typical of hemlock-dominated stands and slight increases in average annual ring width through time, suggesting that the contiguous site is more favorable for eastern hemlock performance.

Committee: Don Cipollini Ph.D. (Advisor); Thomas Rooney Ph.D. (Committee Member); James Runkle Ph.D. (Committee Member) Subjects: Biology; Botany; Climate Change; Conservation; Demography; Ecology; Forestry

Doctor of Philosophy (PhD), Ohio University, 2006, Plant Biology (Arts and Sciences)

Forests are characterized by dynamism in species composition, structure and function. These dynamics, in turn, are often related to disturbance. These disturbances, therefore, are intrinsically linked to the biology of forest ecosystems. In order to understand and ultimately manage forest ecosystems, the role of disturbance in the systems must be ascertained. Disturbances that occur in forests rarely kill all of the existing trees. Therefore evidence of disturbance in the surrounding landscape is often recorded as a growth response in the surviving trees. In this dissertation I present four projects that were executed to develop an understanding of disturbance and growth dynamics in deciduous forest ecosystems of eastern North America. In each project, analysis of tree-rings (dendroecology), was used as the primary data source in the analyses. The first project focuses on the growth of American chestnut (Castanea dentata) in a Wisconsin oak forest. Castanea dentata exhibited a range of growth responses suggesting plasticity in ecological response that 1) offers promise for restoration efforts and 2) may have contributed to its dominance prior to the chestnut blight. The second dissertation project addresses anthropogenic disturbance and the formation of oak savanna in central Kentucky. Because of the > 300 year depth of the chronology in this project, I was able to develop a hypothetical model linking human population dynamics, land use eras, and ecosystem structure. The third and fourth projects work in tandem. The third project presented a vetting of the commonly employed technique of fire-history reconstruction using fire scars in oak samples. In this project we show that 1) scarring occurs from sources other than fire in the landscape, and 2) that multiple annual fires may not be recorded in the tree-ring record. Overall, the tree-ring record proved effective in fire history reconstruction. In the final project of the dissertation, I used this technique to devel (open full item for complete abstract)

Committee: Brian McCarthy (Advisor) Subjects:

Doctor of Philosophy (PhD), Ohio University, 2005, Biological Sciences (Arts and Sciences)

Invasive species are an environmental problem of increasing global concern. Invasives have been intentionally and accidentally transported across previously impeding barriers to new regions where they interact with native species. One invasive shrub, Amur honeysuckle (Lonicera maackii), was introduced into the US from Manchuria in the late 1800s for conservation and horticultural purposes. Since then, it has become ecologically problematic in open areas and forested habitats. The goals of this research were to (1) investigate the impacts of L. maackii on the structure and composition of native plant communities, (2) measure changes in the productivity of overstory trees at invaded sites using dendrochronological techniques, (3) study the growth and biomass allocation of L. maackii seedlings and generate a predictive model regarding their establishment, and (4) investigate the restoration ecology of this species in terms of its eradication and replacement with native tree species. First, using the chronosequence method, sites with various invasion times were sampled, and long-invaded sites were found to have significant reductions in species richness and have a simplified structure relative to recently invaded and non-invaded sites. Thus, successional trajectories were likely being diverted by L. maackii. Second, trees were cored, and annual tree-ring growth was measured. Reductions in tree growth indicate that L. maackii is able to successfully compete with overstory trees and significantly suppress productivity. Third, L. maackii seedlings were grown in various combinations of light and water and glaciated and unglaciated soils. Findings suggest that light was the most important factor influencing seedling growth. Drought conditions limited seedlings' plastic ability to respond to increases in irradiance, and interestingly, glaciated soil was found to have greater L. maackii growth potential than unglaciated soil. Finally, the most effective means of restoring site (open full item for complete abstract)

Committee: Brian McCarthy (Advisor) Subjects:

Master of Environmental Science, Miami University, 2005, Environmental Sciences

The increasing awareness and threat of exotic and invasive flora in Alaska necessitated a preliminary survey of exotic plant distribution for the nearly 2 million acre Kenai National Wildlife Refuge in Southcentral Alaska. As a Biological Technician Intern at the Refuge my primary responsibility was to develop, write and begin implementation of a plan to survey exotic, invasive and noxious flora. In addition, I was also involved in various side projects including dendrochronological dating of cabin logs and miscellaneous projects such as snowmachine trail use monitoring, double-crested cormorant nest counts and burn severity assessment at the 2005 Glacier Creek fire on Tustumena Lake. The following report details and evaluates my experience.

Committee: Thomas Crist (Advisor) Subjects: