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:

Master of Arts (MA), Ohio University, 2006, Geological Sciences (Arts and Sciences)

A remote sensing investigation was conducted in June 2000 in a mixed-oak forest undergoing successional changes at Black Rock Forest, NY. Leaf litter data was collected throughout the fall of 2000 to assess productivity at the site and to obtain species-specific leaf area(LAI SPP) data for Acer rubrum, Quercus prinus, and Quercus rubrum. There were two objectives in this investigation: to determine (1) whether spectral differences exist at branch-level between the oak and maple groups at this site, and (2) whether the remotely-sensed canopy-level classifications are able to produce estimates of canopy cover for red maple that reflect the forest composition identified with the LAI SPPinformation. Significant multispectral differences were identified for all groups at the branch-level. Canopy-level analyses were restricted to the 550 nm wavelength because of calibration issues with the imaging system. These images were processed using soft classification methods, and produced canopy cover maps of questionable accuracy.

Committee: James Lein (Advisor) Subjects:

Master of Science, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1960, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, Miami University, 2023, Biology

Regeneration failure is a pressing issue in forests throughout eastern North America endangering the health of forests. White-tailed deer (Odocoileus virginianus) and invasive plants potentially contribute to failure by impacting tree seedling growth and survival. This study investigated the individual and interactive effects of deer and woody invasive plants on seedlings in an early successional forest. In a stand of Juniperus virginiana forest near Oxford, OH, we initiated a factorial experiment with each combination of deer access/exclosure and invasive woody plants removed/not removed. We planted native tree seedlings and monitored natural regeneration. Survival of planted Quercus rubra seedlings was lowest in invasive removal plots. Quercus rubra seedlings in deer exclosure plots grew taller, but there was no significant effect on height and survival of Liriodendron tulipifera seedlings. We found a marginally significant interaction of deer and invasives on natural regeneration survival: where deer were excluded, survival was higher where invasives were absent, but where deer had access, survival was much higher where invasives were present. Recruitment of native seedlings was greater in deer exclosure plots. Due to these findings, we recommend land managers in comparable early-successional forests focus on alleviating deer pressure over removing invasive plants.

Committee: David Gorchov (Advisor); Jonathan Bauer (Committee Member); Melany Fisk (Committee Member) Subjects: Biology

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

Doctor of Philosophy (Ph.D.), University of Dayton, 2023, Biology

Ecosystem disturbance and degradation have led to dramatically altered plant communities, necessitating their restoration to return to native states. One disturbance is emerald ash borer, an exotic, invasive insect that has decimated ash tree populations creating gaps in many forest canopies. Due to the influx of exotic invasive plant species, traditional forest recovery has been altered in that plant species establishing in gaps favor invasive shrubs to native tree seedlings. Thus, I measured the growth and survival of native tree species planted within a forest affected by emerald ash borer to determine what species may outcompete invasive species and regenerate into the forest canopy. I found that butternut and shellbark hickory trees had high survival rates compared to red oak, and could be target species for replacing ash trees in stands impacted by emerald ash borer. When fallow fields are dominated by Callery pear, a pervasive new invader in the Eastern US, native plant establishment may be limited. I found that Callery pear tends to invade near forested edges of grassland ecosystems, likely because there is increased propagule pressure from generalist frugivorous birds which forage both in Callery pear invaded areas and on forest edges creating seed rain. Callery pear occurs where there is less ground cover of forbs and grasses suggesting that it either invades in areas that have less plant cover or that it inhibits the establishment of native species. In a lab-based experiment, I found that Callery pear is likely allelopathic and can inhibit the germination of common prairie species which could prevent its establishment. Further, in the field, I found that Callery pear can acidify the soil where it establishes, and it may input carbon into the soil system which changes the activities of microorganisms in the soil. Together, these changes to soil chemistry can reduce the likelihood of native species to establish and can prevent invasive species from establis (open full item for complete abstract)

Committee: Ryan McEwan (Advisor); Jonathan Bauer (Committee Member); Albert Burky (Committee Member); Yvonne Sun (Committee Member); Chelse Prather (Committee Member) Subjects: Biology; Ecology

PHD, Kent State University, 2021, College of Arts and Sciences / Department of Biological Sciences

Plants face diverse and variable herbivore pressures. There are numerous strategies that plants may use to avoid or deter herbivore damage. These strategies include defense production, re-allocation of nutrients, and decreasing nutritional quality of foliage. However, these strategies do not come without a cost and must therefore be deployed efficiently to minimize herbivore damage and maximize overall fitness. It is critical to understand how key plant species defend themselves from herbivores. Oaks (genus Quercus) are a large genus of important species that dominate forests of the northern hemisphere and display a wide range of defensive strategies. They provide a model organism to test better understand selective pressures that dictate the expression of defense traits. Some defensive characteristics employed by oaks may be similar among species (phylogenetic effect). Consequently, I first performed a phylogenetic comparative analysis among 12 species of oaks. To understand phylogenetic constraints, I manipulated location (apical vs. lateral shoot) and intensity (25% vs 75% tissue removal) of simulated herbivory on these oak species. There was no phylogenetic signal in species that were manipulated by location and intensity. However, there were significant phylogenetic effects in the unmanipulated plants. I found that there was a significant trade-off between growth and defense in control plants. I then sought to determine if and how oaks differentiate and defend against different major herbivore types (insects vs. large mammals). I set up a field experiment with deer exclosures and insecticide applications to create four herbivore environments (no herbivores, insect only, deer only, and deer with insect) to test for differential defensive strategies. I found that oaks differ in their responses to insect and large mammal herbivory. I found that oaks increased antinutritive defenses against insect herbivores but decreased foliar nutritive quality when large mammals (open full item for complete abstract)

Committee: David Ward PhD (Advisor); Oscar Rocha PhD (Committee Member); Matthew Lehnert PhD (Committee Member); Don Cipollini PhD (Committee Member); Edgar Kooijman PhD (Other) Subjects: Biology; Ecology; Evolution and Development

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 in Regulatory Biology, Cleveland State University, 2017, College of Sciences and Health Professions

Disturbance regimes, i.e. frequent fires, historically maintained oak barrens until European settlement patterns, and eventually, Smoky the Bear and the fire suppression campaign of the U.S. Forest Service snuffed out the periodic flames. In the absence of a disturbance regime, ground layer floral composition at many historical oak sand barrens will change predominantly because of a buildup of leaf litter and shading of the soils. Termed mesophication, this process of ecological succession will drive Black Oak Sand Barrens to an alternate steady state. A survey conducted on Singer Lake Bog in Green, Ohio, demonstrated that succession shifted the community to red maple-black cherry woodlands more typical of a dry southern forest. In an attempt to revive disturbance, three restoration techniques were applied at ten degraded northeast Ohio oak barrens to contrast their effectiveness in restoring black oak sand barren flora. The three restoration treatments were select canopy tree reduction favoring 5% to 30% tree canopy cover, forest floor leaf litter removal, and prescribed fire. Vegetation responses to manipulations were monitored prior to and following treatment applications, and were compared against both baseline data from before-treatment surveys and paired control sites adjacent treated areas. Imposing disturbance successfully increased species diversity and abundance above that found across Singer Lake Bog compared to sampling made prior to and adjacent to treated areas. Select canopy tree removal exhibited the largest floral responses from targeted barrens species, i.e. graminoids. A forest floor invertebrate family (Carabidea: Coleoptera) was measured for species richness and abundance pre and post treatment, where a noticeable shift occurred away from woodland obligate ground beetles toward open grassland species. Replicating oak barren structure, prior to replicating disturbance processes, is the first step in the ecological restoration of these systems.

Committee: Robert Krebs Ph.D. (Advisor); Joe Keiper Ph.D. (Committee Member); Cathi Lehn Ph.D. (Committee Member); Terry Robison Ph.D. (Committee Member); Michael Walton Ph.D. (Committee Member); Emily Rauschert Ph.D. (Other); Scott Heckathorn Ph.D. (Other) Subjects: Botany; Climate Change; Conservation; Ecology; Environmental Management; Experiments; Forestry; Natural Resource Management

Doctor of Philosophy, The Ohio State University, 1971, Graduate School

Committee: Not Provided (Other) Subjects: Biology

Doctor of Philosophy, The Ohio State University, 2015, Plant Pathology

Sudden oak death (SOD) is a devastating disease of oak and tanoak in the western United States, caused by the non-native, generalist pathogen Phytophthora ramorum Werres et al. Quercus agrifolia Nee (CLO—coast live oak) is a highly susceptible host of P. ramorum in California forests and Quercus rubra L. (NRO—northern red oak) is an important Eastern forest species that is also susceptible to P. ramorum. CLO naturally resistant to P. ramorum have been observed and include trees that fail to develop symptoms of infection or appear to recover after symptom development. Variability in CLO susceptibility has been associated with variation in the concentration of certain phenolic compounds produced in CLO phloem tissue, and putative phenolic biomarkers of resistance were identified from trees already infected with P. ramorum. However, the association between constitutive (i.e. pre-infection) levels of phenolics in naive CLO and variation in host susceptibility has not been examined, and little is known about the relationship between NRO susceptibility and variation in phenolic levels. This research aimed to elucidate chemical mechanisms of resistance and identify factors that may affect the production of phenolic defenses in susceptible Quercus spp., including CLO and NRO, before and after infection with P. ramorum. Time was a significant explanatory factor for the variability of certain phenolics, both within and between years, though overall variation was low and did not appear to be related to variability in CLO susceptibility to P. ramorum. NRO treated with a known, phosphonate-based elicitor of host defenses, were more resistant to P. ramorum, and both constitutive and induced levels of certain phenolics were also significantly impacted. Additionally, new approaches for identifying naturally resistant CLO based solely on constitutive concentrations of phenolics were tested. Four phenolic biomarkers of resistance were partially identified in CLO phloem collecte (open full item for complete abstract)

Committee: Pierluigi Bonello (Advisor); Laurence Madden (Committee Member); P. Larry Phelan (Committee Member); Thomas Mitchell (Committee Member) Subjects: Plant Pathology

Master of Science (MS), Wright State University, 2011, Biological Sciences

My study was conducted to understand tree community structure and how soil moisture and fire frequency influence them. Eighteen plots were placed in the Edge of Appalachia Nature Preserve of unglaciated southern Ohio: nine within a prescribed burn site and nine control sites outside the burn. Sites were stratified in triplicate across GIS-derived integrated soil moisture index (IMI) classes. Burning was done in 1996. Overstory species dbh and sapling species were sampled 1997, 2001, and 2008. Overstory stems were located in 2009 using range finders. Stem locations were loaded into GIS using novel techniques to quantify individual stem IMI values. Nonmetric multi-dimensional scaling identified greater heterogeneity among intermediate and mesic sites than xeric sites. Multi-response permutation procedures did not detect community differences between burned and unburned sites, but did detect strong (A=0.3 to 0.2, T=-3.6 to -4.1) distinct community differences that were statistically significant (P < 0.05) among xeric, intermediate, and mesic IMI classes. Analysis of variance identified significant initial effects of burning on Carya saplings and overstory Sassafras albidum stems, as well as lasting effects significant on Carpinus caroliniana. ANOVA detected significant differences across all sampling years in sapling relative number for Acer rubrum, Sassafras albidum, and Carpinus caroliniana saplings, as well as Quercus prinus, and Liriodendron tulipifera overstory stems between IMI classes. Bonferroni adjusted Kolmogorov-Smirnov tests were used to identify and quantify IMI habitat restrictions of species. Quercus prinus dominated xeric sites (IMI quartiles 18-24), Carya occupied intermediate sites (IMI quartiles 22-44), Acer saccharum occupied intermediate to mesic sites (IMI quartiles 33-44), Sassafras albidum (IMI quartiles 20-40, IMI median 43) and Liriodendron tulipifera (IMI quartiles 39-45) were restricted to mesic sites. My r (open full item for complete abstract)

Committee: James Runkle PhD (Advisor); James Amon PhD (Committee Member); Thomas Rooney PhD (Committee Member) Subjects: Ecology

Master of Science, The Ohio State University, 1937, Plant Biology

Committee: E. Transeau (Advisor) Subjects:

Master of Science (MS), Ohio University, 2005, Plant Biology (Arts and Sciences)

In eastern deciduous forests, prescribed fire and thinning are used as tools for a variety of management goals, including altering fuel loads. The specific effects of these treatments on fuel dynamics are relatively unknown in mixed-oak forests. Likewise, specific fire behavior from fuel load and moisture is relatively unknown in these ecosystems. First, I examine the dynamics of multiple classes of fuels, from litter and duff to large, coarse woody debris, three-years following thinning and prescribed fire. Fine fuels recovered rapidly following treatments, while larger, sound fuels continue to exhibit effects of thinning. Second, I manipulate fuel loads and fuel moisture levels in a common garden, trial burn experiment. Fires burned hotter with elevated fuel loads or decreased fuel moisture. My results can be used collectively to predict the effects of silvicultural treatments on future prescribed fires, and provide a realistic baseline for fuel loading and fire behavior models.

Committee: Brian McCarthy (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 2012, Biology

Most pryrogenic ecosystems are endangered due to encroachment of fire-sensitive species and loss of fire-tolerant species caused by altered fire regimes, especially fire suppression. Restoration of these degraded systems typically involves the reintroduction of fire via prescribed burning. I evaluated the efficacy of prescribed fire in reducing woody plant encroachment in fire-suppressed oak-dominated ecosystems in the Bluegrass Region of southern Ohio. In the first study, I tested the effects of biennial fire and a fire surrogate (clipping) on woody and herbaceous vegetation abundance in oak barrens. I found that fire and clipping produce similar responses in vegetation, and although these treatments reduce the aerial cover of shrubs, they do not lessen shrub resprouting or promote herbaceous plants. Next, I described the characteristics of oak-dominated forests prior to the reintroduction of fire. My snapshot of seedling layer vegetation in these forests highlights the variation in vegetation and environmental factors over small and large spatial scales. Despite their distinctions in composition, the structural patterns at all the forest stands provide evidence for a general shift in composition from oak (Quercus) to maple (Acer) dominance. Oaks are failing to regenerate and are being replaced by actively recruiting maples. Fires are predicted to reverse this shift by acting as a filter for maples resulting in the promotion oaks. In my final study, I tested this prediction and evaluated the effects of fire season and topkill with and without heating on forest seedling composition and abundance. I found no clear effect of fire season, or heating, and only limited support for the prediction that fires act as a filter for maples. Overall, these results indicate that fire might maintain initial vegetation conditions, but is not effective in reversing encroachment in oak-dominated ecosystems. Despite the limited spatial and temporal scale of my studies, these results a (open full item for complete abstract)

Committee: Joseph Koonce PhD (Advisor); Roy Ritzman PhD (Committee Chair); Robin Snyder PhD (Committee Member); David Burke PhD (Committee Member); Michael Benard PhD (Committee Member); Matthew Dickinson PhD (Committee Member) Subjects: Biology; Ecology; Forestry

Master of Science, University of Toledo, 2013, Biology (Ecology)

Extreme weather events are a growing focus of global climate change research. Extreme events, which occur abruptly and unpredictably, are often more detrimental to terrestrial vegetation than gradual shifts in climate. One type of event, the summer heat wave, may already be increasing in some areas of the world. Large-scale reductions in Net Primary Productivity and mortality have been reported during heat waves in forested ecosystems. Unfortunately, our understanding of how abrupt heat-stress affects woody species during heat waves lags behind our knowledge of herbaceous species that have been more widely studied in experimental manipulations. A few studies of herbaceous species also suggest that the coupling of soil heating to air heating can change the overall plant response to heat waves. To investigate air vs. air+soil heating in woody species, we manipulated the temperature of both shoots and roots separately for both white and black oak seedlings by insulating the soil during heat-stress to the shoot (35 vs. 40°C for 4 days, white oak; 35°C for 8 days, black oak). Interestingly, at moderate heat-stress temperature (35°C), net photosynthesis declined and internal CO2 concentration of leaves increased more when the roots were insulated in both species. Hence, concurrent soil warming prevented metabolic damage to leaves during moderate heat-stress, suggesting that direct heat to the roots increased shoot thermotolerance. In both experiments, differences in air vs. air+soil heating effects on root respiration were directly related to differences in soil temperatures, such that root respiration was higher with air+soil heating. In neither experiment were soil temperature effects related to plant water status. These results suggest that both direct and indirect effects of soil warming may occur in woody species during a heat wave, but that the response may depend on the severity and duration of the heat-stress. Future research is needed to determine t (open full item for complete abstract)

Committee: Scott Heckathorn (Committee Chair); Daryl Moorhead (Committee Member); Wayne Shepperd (Committee Member) Subjects: Ecology; Environmental Science; Forestry; Physiology; Plant Biology; Plant Sciences; Urban Forestry