Master of Science (M.S.), University of Dayton, 2012, Biology

Diversity and compositional dynamics in deciduous forests of eastern North America are subject to a suite of potentially interacting ecosystem drivers, including, but not limited to, anthropogenic and natural disturbances, fire, exotic species invasions, climate shifts, and environmental gradients. The structurally complex Eastern Deciduous Forest is one of the most diverse temperate ecosystems, and despite decades of ecological research, many fundamental questions regarding spatial and temporal dynamics are either hotly debated or remain unanswered. The body of work presented in this thesis is part of an ongoing long-term botanical analysis of Big Everidge Hollow, a watershed containing old-growth forest within the Lilley Cornett Woods Appalachian Research Station on the Cumberland Plateau of eastern Kentucky. The relatively pristine condition of this site has provided a unique opportunity to study forest dynamics in an area of minimal anthropogenic disturbance. The first chapter of this thesis describes changes in the floristic community that have occurred since the last floristic survey of the site in 2001. Twenty-three new species records are reported, some of which are invasive species that pose a threat to the biological integrity of the site. The second chapter examined baseline dynamics of woody understory over a decade, described the relationships between diversity and surrogate measures of productivity (density and cover), and investigated the reaction of shrub- and ground-layer vegetation to a recent fire in one portion of the study site. Decadal oak-maple dynamics in the woody understory of this old-growth stand did not fully support the hypothesized oak-to-maple dominance shift thought to be occurring in forests across eastern North America; changes in shrub- and ground-layer populations of maple (Acer spp.) were erratic while oak (Quercus spp.) populations appeared stable. Unimodal relationships between diversity and productivity surrogates were found (open full item for complete abstract)

Committee: Ryan W McEwan Ph.D. (Committee Chair); Albert J Burky Ph.D. (Committee Member); M. Eric Benbow Ph.D. (Committee Member) Subjects: Botany; Ecology; Plant Biology

Master of Science in Biological Sciences, Youngstown State University, 2023, Department of Biological Sciences and Chemistry

Forest canopy gaps are integral for regenerating most plants and maintaining regional diversity. However, native diversity in gaps is often compromised by exotic plant dominance and in the eastern United States, chronic overbrowsing by white-tailed deer (deer; Odocoileus virginianus). Notably, decades-long, near ubiquitous deer overabundance limits opportunity to study the dynamics of communities lacking persistent overbrowsing. Here, we ask how does spring and fall herbaceous and woody composition differ between areas with ≥50 years of low (~7 deer/km²) and high deer density (≥20 deer/km²). This was done in 2-14-year-old canopy gaps, ranging in size from 83-522m² (median: 230m²), in both mesic and drier temperate forest. Paired deer exclosure vs. control plots in two-year-old harvest gaps were also followed for three growing seasons to assess exclusion effects in low deer density areas only. Composition of browsable native and exotic plants (≤2m in height) did not differ between exclosure and control plots, indicating gap regeneration dynamics were unaffected by low deer density after three growing seasons. For spring flora, exotic relative cover increased with gap age, but native and exotic diversity did not differ across gap size, deer density, and habitats. However, for fall flora, exotic cover increased with gap age when deer were abundant, where communities averaged 380% higher non-native coverage. Fewer deer were associated with 75% higher native richness, 50% higher native diversity, and 60% more native cover across gap ages and habitats. Additionally, sapling height and stem density of red (Quercus rubra) and pin oak (Quercus palustris) were five- to twenty-fold higher with fewer deer. We find that managing white-tailed deer at roughly twice their historic abundance for 67-years facilitates all measured aspects of fall-flowering native understories, including early recruitment of four important canopy species, and reduces exotic plant abundance. (open full item for complete abstract)

Committee: Ian J. Renne PhD (Advisor); Thomas P. Diggins PhD (Committee Member); Walter P. Carson PhD (Committee Member) Subjects: Animals; Botany; Ecology; Forestry; Natural Resource Management; Wildlife Management

Master of Science, Miami University, 2022, Botany

Overabundant deer in the United States are a threat to forest regeneration and future forest composition due to browse on seedlings of preferred species. Controlled hunting programs are common for deer population management in parks. In this study, I investigated the Cincinnati Parks system's hunting program to determine if it was reducing deer density enough to facilitate tree regeneration. To do this, I completed surveys of seedlings, saplings, trees, palatable herbs, and invasive shrubs in five different sites within the Cincinnati Parks System. I found that in all sites, sapling densities were much lower than the 1,000 saplings/ha considered sufficient for forest regeneration. Four sites had seedling densities above 2,500 seedlings/ha considered sufficient for forest regeneration. However, when species that cannot contribute to future canopies (Fraxinus spp. and Asimina triloba) were excluded, all sites were below that density. Species preferred by deer were common in the canopy of the forests but were sparse in the seedling and sapling layer, suggesting that deer have shifted tree species composition over time. Deer densities have not decreased since 2007, suggesting that the hunting program is not decreasing populations sufficiently in the Cincinnati Parks. To facilitate tree regeneration, other management strategies should be considered.

Committee: David Gorchov (Advisor); Melany Fisk (Committee Member); Thomas Crist (Committee Member) Subjects: Botany; Ecology; Wildlife Management

Master of Science, The Ohio State University, 2021, Environmental Science

Eastern oak-hickory forests are threatened by multiple factors including the increasing abundance of invasive species and the process of mesophication, the transition from xeric (shade intolerant but drought tolerant) to mesic (shade tolerant but drought intolerant) species. The encroachment of forest understories by both invasive and native mesic species has altered regeneration and recruitment processes. Increasing invasive species and mesophication have created a need for further research on how biotic and abiotic filters and species functional traits influence regeneration of native trees. Research focused on understanding different controls on the regeneration and recruitment of native tree species, and the efficacy and efficiency of two invasive species control methods, was performed at The Ohio State University's Pomerene Forest Laboratory in Coshocton, Ohio. To understand processes of regeneration and recruitment, abiotic and biotic filters were used in generalized linear models to identify patterns in abundance of 19 plant functional types × size class combinations, while Non-Metric Multidimensional Scaling (NMDS) was used to describe patterns in understory species composition. Models of functional type abundances were found to have a wide range of predictive ability across the functional type × size class combinations, due to small sample sizes and other ecological conditions not examined in this research (such as land use history). The abundance of the functional types was influenced by invasive species. The invasive species' high plasticity allowed higher levels of establishment in areas rich in available resources and forced native trees to regenerate and recruit in conditions not suitable to their functional traits. Species composition was heavily influenced by invasive and native shrubs, isolating the Walnut/Oak canopy community group from the other 4 canopy community groups. After regeneration and recruitment patterns were identified, restoration ma (open full item for complete abstract)

Committee: G. Matthew Davies (Advisor); Benjamin Wenner (Advisor); Roger Williams (Committee Member); Matthew Dickinson (Committee Member) Subjects: Environmental Science; Natural Resource Management

Master of Science (M.S.), University of Dayton, 2020, Biology

Arctic warming may influence the global climate system by altering of ecological processes that preserve vast quantities of carbon stored in permafrost. Thirty-two percent of global forest carbon stock is stored in boreal forests, and a majority of this carbon is found in Russian forests. Boreal forests of the Siberian Arctic are dominated by monospecific stands of Larix cajanderii that grow on permafrost and may sequester up to 35% of the carbon stored in Russian boreal forests. Due to the spatial extent of its range, the single-species nature of this forest, and permafrost underlying these forests, Larix cajanderii is a crucial component of the Siberian Arctic carbon sink and may be a key regulator of global climate. This boreal tree species is symbiotic with ectomycorrhizal fungi, which are critical to their growth. Post fire recruitment density of L. cajanderii varies widely, and may be impacted by surrounding vegetation and fungal communities. In this study, I investigate factors affecting ectomycorrhizal fungal (EMF) colonization of roots of L. cajanderii in plots representing a gradient of seedling density after fire in northeast Siberia. In nine burn scars among upland or lowland landscape positions, I measured soil characteristics, seedling metrics, and surrounding EMF inoculum sources to examine the influence these factors have on EMF colonization of tree seedling roots. To determine the effect of EMF colonization on larch seedlings, I quantified percentage of fine root length colonized by EMF for 110 harvested recruits across density treatments. Seedling density treatments of none, moderate and high were observed and a control treatment located in the adjacent unburned stand. EMF were present on nearly all samples collected for analysis. I found that there is a positive relationship between EMF colonization and fresh seasonal growth of recruited seedlings. Together these results demonstrate that EMF may be essential to seedling success. Site topography (open full item for complete abstract)

Committee: Ryan McEwan (Advisor); Rebecca Hewitt (Committee Member); Chelse Prather (Committee Member); Albert Burky (Committee Member) Subjects: Biology; Climate Change; Forestry

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

Many Quercus-Carya forests in the eastern United States are experiencing compositional shifts due to the failure of the overstory species to regenerate, while mesophytic species, i.e., Acer rubrum, Acer saccharum, and Fagus grandifolia, increasingly dominate their regeneration layers. The Wayne National Forest (WNF) of southeastern Ohio is largely Quercus-Carya forest ecosystem types, although the sapling regeneration is often dominated by the aforementioned mesophytic species. Through the 2018 resampling of 98 permanent plots established on the Marietta Unit of the WNF in 1993, this research investigates changes in sapling species composition and abundance. Statistically significant changes were observed in seven of the species in the total sapling layer: Acer rubrum, Acer saccharum, Aesculus flava, Carya glabra, Cornus florida, Fagus grandifolia, and Hamamelis virginiana. Within the subcategory of small saplings (stems 0.1-5.0 cm DBH), the ten species that had statistically significant changes were Acer rubrum, Acer saccharum, Carpinus caroliniana, Carya glabra, Cornus florida, Fagus grandifolia, Hamamelis virginiana, Nyssa sylvatica, Prunus serotina, and Ulmus rubra. In the subcategory of large saplings (stems 5.0-10.0 cm DBH), there were two species that had statistically significant changes: Cornus florida and Fagus grandifolia. Overall, the mesophytic species Acer rubrum, Acer saccharum, and Fagus grandifolia continue to dominate the sapling layers of the sampled forests. Fagus grandifolia had significant differences in total saplings, as well as both small and large sapling subcategories. In all three classes, Fagus grandifolia increased in stems per hectare and relative density. In the total sapling and small sapling categories, Fagus grandifolia became the most abundant species. Acer rubrum and Acer saccharum had statistically significant changes in total and small sapling categories, where the stems per hectare and relative densities of both species decre (open full item for complete abstract)

Committee: David Hix PhD (Advisor) Subjects: Ecology; Forestry; Natural Resource Management

Doctor of Philosophy, The Ohio State University, 2017, Entomology

Emerald ash borer (EAB) has killed millions of trees since its accidental introduction to southeastern Michigan more than 20 years ago. Near the invasion epicenter, nearly all mature ashes have died, reproduction has ceased, and the seed bank depleted, leaving an “orphaned” cohort of established seedlings and saplings. Because of high seedling mortality, it is possible that seedlings that established recently may have lower genetic variation than those that established before the EAB invasion. Insecticides can successfully protect ash trees from EAB and clusters of treated ash trees may slow ash mortality by reducing EAB densities. Therefore, insecticides, in high enough densities, may protect ash trees in order to maintain reproduction, regeneration, and genetic variation. I tested these questions at Five Rivers Metroparks in southwestern Ohio and the Upper Huron River Watershed in southeastern Michigan. From 2014 – 2016, green and white ash mortality differed between parks, with survival higher at Sugarcreek, Englewood, and Germantown Metroparks (low EAB impact) than at Cox Arboretum, Taylorsville, and Twin Creek (high EAB impact). I found that survival of untreated green-white ashes increased with percentage of ash phloem area treated, but only in parks with low EAB impact. Additionally, survival of untreated trees was higher when the nearest treated ash was within 100 m, percentage of ash phloem treated was high, and EAB impact was low. However, this pattern was not observed in parks with high EAB impact. These results suggest that treating ash trees with insecticide may slow the progression of ash mortality if the program is initiated when ash mortality is still low. There were more flowering green and white ash trees (treated and untreated) in plots with higher percentage ash phloem treated. In parks with high EAB impact, seedling density was low and was not affected by insecticide treatment. In parks with low EAB impact, seedling densities increased w (open full item for complete abstract)

Committee: Daniel Herms (Advisor); Mary Gardiner (Committee Member); P. Charles Goebel (Committee Member); Andrew Michel (Committee Member) Subjects: Ecology; Entomology

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

Eastern deciduous forests include a remarkable number of plants that are utilized widely for their medicinal properties. However, the long-term sustainable use of medicinal forest plants requires that methods be developed for restoring and cultivating them in natural and semi-natural settings. This study examined the seed regeneration biology of several perennial forest herbs that are internationally traded in the increasingly lucrative botanical medicines industry. Specific objectives were to: (1) determine how environmental cues (temperature, light, substrate, and burial) regulate dormancy-break and carry-over in seed populations of Actaea racemosa (black cohosh), Hydrastis canadensis (goldenseal), and Sanguinaria canadensis (bloodroot); (2) experimentally evaluate seedling recruitment probabilities of A. racemosa, H. canadensis, S. canadensis, and Panax quinquefoliusin different forest microenvironments defined by varying levels of leaf litter and opposing topographic positions; (3) classify seed dormancy and determine optimum germination temperatures for Collinsonia canadensis (stoneroot) and Dioscorea villosa (wild yam); and (4) quantify survival rates and dormancy-levels of A. racemosa and H. canadensis seed populations stored in artificial conditions. Results from these studies showed that: (1) germination probabilities can vary widely when seeds experience different environmental cues, although temperature is the primary factor regulating dormancy-break and germination; (2) some perennial forest herbs can form persistent seed banks and spread germination across time; (3) leaf litter and topographic position can act as ecological filters during early life-history stages; and (4) storing seed populations prior to outplanting reduces viability in H. canadensisseeds and deepens dormancy levels in A. racemosa seed. Recommendations are made for cultivating, managing, and restoring these species in the eastern deciduous forest landscape.

Committee: Brian McCarthy (Advisor) Subjects: