Doctor of Philosophy, Miami University, 2024, Biology

Climate change has caused shifts in species ranges, including oak and hickory. These species are in high demand commercially, and benefit from forest management for regeneration. Terrestrial invertebrates have shown major declines in biodiversity and biomass due to anthropogenic disturbances and climate change. Due to their sensitivity to disturbance, some terrestrial invertebrate taxa are proposed as bioindicators. The goals of this dissertation are to quantify the impact of different forest management practices on invertebrates along a mesic to xeric topographic gradient. Additionally, I evaluated two bioindicator taxa, ants and carabid beetles, to understand how well they can be used as indicators of environmental changes and the overall soil invertebrate community composition. This study took place in Morgan-Monroe and Yellowwood State Forests in central Indiana. The study design consisted of nested hierarchical design with management treatments along northeast and southwest facing aspects as well as paired transects at ridgetops and lowlands. Soil and litter invertebrates (mesofauna), ants, and beetles were sampled along each transect, in addition to environmental metrics of soil characteristics, tree composition, and forest floor composition. Transects were sampled over a total of three years to understand temporal changes and landscape variation. For each invertebrate group, abundance, diversity, and community composition were compared to the environmental and design variables. Soil mesofauna biomass was also measured, and associations with ants and beetles were also analyzed. All three communities investigated had a shift in species composition caused by management and topography. Invertebrate biomass and diversity were lower at xeric sites compared to mesic sites. At sites with forest management, this trend became stronger. Ants showed variable responses to management due to the habitat heterogeneity in successional forests; ant community composition w (open full item for complete abstract)

Master of Science, The Ohio State University, 2023, Environment and Natural Resources

The American elm (Ulmus americana) was once found lining the streets of many cities. Now, with the continued threat of Dutch elm disease (Ophiostoma ulmi and O. novo-ulmi), large American elms are uncommon. Efforts by researchers have led to the development of Dutch elm disease-tolerant American elm selections. Yet we have little understanding of how these selections may react to a range of environments when used in restoration. Our goal is to better understand how DED-tolerant elms differ in phenology across locations and genotypes to develop predictions for how they may respond to restoration and future climate change. In common gardens in central Ohio and northern New England, we tracked the progression, time to initiation and time to completion of budbreak and leaf-out, in DED-tolerant elms. We assessed individuals across five genotypes – Princeton, R18-2, Del-2, New Harmony, and Valley Forge – which have been cultivated to produce DED-tolerant lines. Phenological data, i.e., dates at which a tree's buds reached a given stage, collected in central Ohio over two field seasons (spring 2022 and spring 2023) and in New England over one field season (spring 2023) were used to determine the relationship between time and phenology, and the effects of location, year, genotype, and genotype interactions. Data on bird presence and use of elm trees in sites in central Ohio during spring 2023 were used to better understand the potential role of restored elms within the landscape. We found that year and location effects were significant at more stages than genotype or interaction effects – colder locations and the year with later spring warming tended to result in elms reaching key phenological stages later than warmer locations and the year with earlier spring warming. This indicates that environmental factors may have a stronger influence on spring phenology in American elms than genotype. We also found that bird presence had a strong positive correl (open full item for complete abstract)

Master of Science, The Ohio State University, 2023, Evolution, Ecology and Organismal Biology

Invasive temperate lianas are ecologically impactful and increasing in abundance in North America, but information regarding their ecophysiology is relatively scarce. I selected four introduced species representing potentially contrasting shade strategies, "light-demanding" Ampelopsis brevipedunculata and Celastrus orbiculatus and shade-tolerant Hedera helix and Euonymus fortunei, to compare their responses to either neutral shade or shade with a reduced R:FR ratio of 0.88 from the ambient 1.3, with the reduced-R:FR shade intended to more closely resemble canopy shade and induce a phytochrome-mediated shade avoidance response. I tested whether responses differed by species and by light quality, measuring five morphological and physical traits in all species and four photosynthetic traits in the shade-tolerant species. Mortality in shaded Ampelopsis was high along with Celastrus in all conditions, while no mortality was observed in shade-tolerant species. Differential responses to light quality were detected in three morphological traits and one photosynthetic parameter. Relative to neutral shade, leaf mass as a proportion of total aboveground biomass increased in Ampelopsis and Celastrus in reduced R:FR shade while increasing in both treatments for shade-adapted species. Internode length was only greater in R:FR-reduced shade than neutral shade for Celastrus, with no difference in elongation detected between shade treatments in any other species. These changes in allocation patterns and gross morphology were limited to the light-demanding species. While internode length was greatest for all species in control conditions, a subsequent analysis of biomass-adjusted internode length indicated that internodes were longest in the shade treatments, and nonsignificantly longer in R:FR-reduced shade relative to neutral shade. Hedera biomass was greater in R:FR-reduced shade, increasing nonsignificantly in all other species. Quantum yield (φ) was greatest in Hedera but unaffe (open full item for complete abstract)

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.

Ph.D., Antioch University, 2023, Antioch New England: Environmental Studies

Previous research has demonstrated that practicing forest bathing has significant positive effects on well-being. However, few studies have investigated whether forest bathing increases adolescent well-being despite the growing adolescent mental health crisis in the United States. Similarly, few studies have explored forest bathing's impacts on connectedness to nature. Considering the ongoing environmental crisis, determining if forest bathing increases connectedness to nature is a critical expansion of forest bathing research, as connectedness to nature is linked to environmental care and concern. This study investigated the possibility that forest bathing, a nature-based mindfulness practice, could increase adolescent mental well-being and connectedness to nature and sought to determine participants' experiences of practicing forest bathing. This study used a convergent parallel mixed-methods design that was partially co-created with 24 participants aged 16-18 as part of a youth participatory action research (YPAR) project where participants practiced forest bathing three times over three weeks. After practicing forest bathing, participants' mental well-being increased significantly, as measured by the Warwick Edinburgh Mental Well Being Scale. Connectedness to nature also increased significantly as measured by the Connectedness to Nature Scale. Participants described reduced stress and increased feelings of relaxation, peace, and happiness as well as increased connection to nature, gratitude for nature, concern for nature, and desire to care for nature. Although this is one of the first studies to examine forest bathing impacts on participants' connectedness to nature, these findings correlate with other studies showing that spending time outside in nature increases connectedness to nature and care and concern for the environment. People working with adolescents could consider forest bathing as a practice that increases connectedness to nature while also incr (open full item for complete abstract)

PHD, Kent State University, 2023, College of Arts and Sciences / Department of History

Based on a critical reading of colonial archives and extensive use of oral sources, this dissertation argues that indigenous custodians of the landscape in semi-arid regions of the Zimbabwean Lowveld have a longstanding experience of harnessing their environmental literacy and detailed knowledge of nature to combat climate change. Starting with colonial encounters and contested boundaries of knowledge in Southern Rhodesia (present day Zimbabwe) since the early twentieth century, I demonstrate that oral traditions survived the onslaught of colonialism and offered new generations ways of responding to climate change. I use empirical examples to demonstrate that indigenous knowledge systems (IKS) have been obscured under the veneer of colonial historiography, hence, the importance of recovering African cultural achievements and indigenous agency to the historical record. This dissertation examines the adoption of various coping strategies and sustainable agricultural practices initiated by indigenous people to promote climate smart agriculture and identifies the factors that influence adoption of certain adaptive practices. Water has been a central and defining factor of Africa's development trajectory. A growing body of literature has demonstrated that agricultural yields have been declining in developing countries, including Zimbabwe, due to the impacts of climate change. Indigenous experiences, conceptions and perceptions have played a vital role in the adoption of climate-smart agricultural practices. Indigenous farmers are at peace with modernity and modernization, but in the absence of modern technologies and state support, they have been going back to traditional forms of development. The interrelated objectives of climate change mitigation, adaptation and food security were simultaneously sustained through the hybrid integration of indigenous and modern farming practices in agricultural production and sustainable development planning. Indigenous knowledge sys (open full item for complete abstract)

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

Over the past several decades, changes in land use, extirpation of predators, conservation measures, and climate change have driven rapid and uncontrolled increases in large herbivore populations around the world. In temperate forest systems, selective foraging by overabundant ungulates has been negatively impacting the diversity and structure of plant communities for many years, with cascading impacts on arthropod and songbird communities as well. Species loss is often so complete that plant communities cannot recover diversity even when ungulate densities are reduced. However, an emerging body of research documents common landscape features providing localized relief from intense herbivory pressure. In these locations, diverse plant communities flourish, and they may also be effective propagule sources for re-colonizing the landscape if ungulate densities return to historical levels. Here, I explore the history and impacts of white-tailed deer herbivory on eastern North American forests (Chapter 1), I report the results of a deer exclosure experiment showing the legacy effects of chronic over-browsing (Chapter 2), and I present a systematic review of refuges from ungulate herbivory worldwide (Chapter 3). Despite the intense pressure of long-term herbivory and the persistence of legacy effects, refuges provide hope for a healthier and more diverse forest plant community in the future.

Master of Science, The Ohio State University, 2023, Plant Pathology

My work aimed to develop a comprehensive environmental risk mapping framework for beech leaf disease (BLD) using an ensemble approach in species distribution modeling. The recent emergence of BLD poses a significant risk to American beech trees in the northeastern region of the United States, and accurate risk mapping can assist in targeted management strategies, particularly biosurveillance. To generate reliable present and future models, I first modeled the current distributions of American beech in its full U.S. range as well as BLD. Then I explored the impact of climate change on future American beech habitat suitability as well as BLD distribution. The models integrate present and projected climate data to anticipate alterations in suitable habitats and potential shifts in species distribution ranges. The ensemble approach I used combines multiple boosting and bagging approaches with machine learning or regression-based algorithms. These include multiple adaptive regression splines, flexible discriminant analysis, random forest, and boosted regression trees to generate a robust risk map. The findings of this research offer a crucial understanding for managing forests and preserving ecosystems, which encompasses pinpointing vulnerable regions for BLD and evaluating the potential influence of climate change on American beech populations. The ensemble approach employed in species distribution modeling effectively produced highly predictive maps, while the habitat suitability models emphasized the significance of taking climate change into account when devising conservation strategies.

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)

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

Vocal communication is a common trait across the animal kingdom and offers benefits in its adaptability to diverse habitats and landscapes. In particular, songbirds inhabit a wide array of niches, habitats, and landscapes and consequently produce unique and specialized vocalizations that are adapted to their environment and different behavioral needs. Songbirds' communications take place within acoustic landscapes comprised of biotic (other singers and noise) and abiotic (structures that reflect, absorb, or scatter sound) factors. Changes to the physical structure of acoustic landscapes as a result of climate change or silvicultural practices can alter the acoustic landscapes in which songbirds have adapted their acoustic signals. This investigation aimed to characterize acoustic landscapes of different forest habitats and effects of forest structures on potential acoustical communication. In three forest types, dry-mesic northern forest, rich conifer swamp, and boreal forest, we recorded pure tones within songbirds' auditory range (2 to 8 KHz) at 6 different distances along a transect and quantified different aspects of the vegetation through which the pure tones traveled. Four transect per forest type were used and sounds were recorded at two different heights (1 and 5 m). Linear regression analysis was used to determine if the pure tones were attenuated differently along transects, between sampling heights, and across forest types. Our analysis revealed that in the conifer swamp, sound was attenuated at a higher rate than either the dry-mesic northern forest or the boreal forest, and at our sampling height of 5-meters, pure tones' clarities were degraded more. Subsequent analyses showed the number of large trees, logs, and area of wood were likely the main drivers of difference in the attenuation of the amplitudes of the pure tones. These differences in vegetation as well as differences in attenuation of different frequencies amplitudes and clarities provide impl (open full item for complete abstract)

Master of Science, The Ohio State University, 2023, Environment and Natural Resources

Future predictions show dramatic increases in fire probability in the eastern U.S. where more frequent and human-caused fires exist compared to the west. Therefore, more attention needs to be given to understanding the factors of fire behavior and fire environment in eastern forests. However, quantification of future trends in fire activity is challenging owing to the lack of spatially complete and consistently derived data. The regional and spatial variability, complex and non-linear interactions between weather, vegetation, and human activity add more uncertainty to future fire behavior. In this study, we examined the potential effects of topographic variables and forest attributes on the fire environment at the fine scale in southeast Ohio. Ninety-four plots were established to quantify three factors of terrain: aspect, slope position, and slope steepness (o). Fuel loads and fuel composition were analyzed to capture the interaction of terrain and fuel. Over the three topographic variables, aspects and slope position played a major role in the differences in forest structure and certain species abundance. This subsequently influenced the composition and characterization of the fuels. An ignition experiment was conducted under controlled laboratory conditions to determine how the differences in fuel composition, based on species, arising from different topographic positions can influence the potential differences in fire behavior. A linear correlation was found between fuel load composition (oak vs. maple) and forest attributes. Significant differences in the flame temperature between oak and maple were discovered.

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

Old-growth forests are ecosystems that have experienced little to no anthropogenic change, granting them the ability to absorb and store vast quantities of carbon, serve as safe havens for rare and endangered species, and house menageries of biodiversity. According to global land surveys, about 36% of old-growth is left globally, with less than 6% of this existing within the United States. Data collection of species-specific rates for tree populations in repeatedly sampled permanent plots allow researchers and land managers to anticipate responses to anthropogenic and biological ecosystem stressors and to create strategic and robust conservation plans. In this project, we leverage forty-one years of scientific data collection of the old-growth forest Hueston Woods to analyze long-term dynamics during an era of compounding anthropogenic pressures. Our study site is a permanent 100 m x 105 m plot in Hueston Woods State Nature Preserve, located in Preble County, Ohio. Vegetation sampling was first implemented by Dr. John Vankat at Miami University, Ohio, in 1981 and was repeated in 1988, 1994, and 2000, before being handed to Dr. McEwan's Forest Ecology Lab at the University of Dayton for this projects sampling in 2022. We analyzed changes in woody species importance in terms of relative density, relative frequency, and relative basal area, as well as in historical canopy gap production to understand long-term forest change. The system is in a state of reaction to “multiple interacting ecosystem drivers,” primarily overpopulated white-tailed deer (Odocoileus virginianus), which have existed in high enough densities to negatively impact vegetative communities in the eastern United States since the mid-to-late 20th century, and the invasive emerald ash borer (Agrilus planipennis), which has inflicted a 99% mortality rate upon the genera Fraxinus in North America since its introduction to the United States in 2002. For the overstory, we predicted that (1) importance val (open full item for complete abstract)

Master of Arts, Miami University, 2022, Geography

The accurate attribution of fire detections to a specific fuel source type is of critical importance for the assessment of emissions, tracking energy and industry expansion, and informing wildfire management. The Arctic presents a particular set of challenges to accurate source attribution owing primarily to its remoteness, diversity, and the difficulty inherent in imaging at extreme latitudes. This study describes the development of a novel machine learning application for the identification of persistent sources of fire in high northern latitudes, especially those persistent sources which represent non-biomass burns. Emphasis is placed on the integration of existing data alongside measures of a fire detections' persistence in space and time, as well as other fire characteristics. The results provide important contextual information about the probability of a given fire detection being associated with a persistent non-biomass burning source. Assessment of the model at various persistence probability cutoffs is given to provide guidance for its application. Future improvements to the model are discussed as well as the limitations of the current iteration which estimates all persistent pan-Arctic fires for 2018.

Doctor of Philosophy, The Ohio State University, 2022, Agricultural, Environmental and Developmental Economics

The forest ecosystem can be affected by forest distribution changes, management changes, and forest loss. Change to forest ecosystems is not only an environmental science problem but also an economic problem since both market and policy changes can influence forest ecosystems. The three chapters of my dissertation discuss the impacts of timber market change on forest distribution, explore how forest policy change affects forest planting investments in another region, and illustrate the relationship between overlapping tenure and forest loss. The first chapter examines the distribution and movement of forest species in the Eastern and Southeastern US with a spatial logistic model and assesses how natural and socioeconomic factors have influenced forest migration. In this research, we derive a 30-year presence/absence dataset from the Forest Inventory and Analysis (FIA) database. The species distribution analysis suggests that besides climatological and geophysical factors, socioeconomic factors can also impact the probability of the presence of tree species. Furthermore, the impact of timber prices varies on trees of different ages. This research highlights how timber market variations can impact forest distribution by influencing landowners' management decisions. Our findings highlight the unintended environmental consequences of changes in timber and agriculture markets. The environmental policies, such as habitat protection and forest preservation, should take timber market consequences into consideration The second chapter examines how federal timber harvesting restrictions in the Pacific Northwest in the early 1990s resulted in an increase in softwood planting in the Southern US. This is one of few papers that discuss the change in investment in planting caused by a policy change in another region. This study develops a unique dataset of county-level loblolly planting derived from historical timber inventory data. The results indicate that the loblolly pl (open full item for complete abstract)

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

The prolonged overabundance of white-tailed deer (Odocoileus virginianus) throughout the deciduous forests of eastern North America has resulted in widespread changes in the understory community. Studies have demonstrated that the exclusion of deer can allow some aspects of the understory to recover, but there are strong time-lags for deer-preferred species. Additionally, these exclosures only test the presence/absence of deer, which is not a feasible management option or desirable as deer are a part of the community. Here I evaluate how large-scale deer density manipulations within the Kinzua Quality Deer Cooperative of Pennsylvania affected understory vegetation communities. Using data from six periodic intensive vegetation surveys I assessed multiple measures of understory response, from both woody and non-woody components of the understory, including potential time-lags in recovery. Most measures I used showed some recovery while deer densities were reduced, and negative responses to increasing deer density. Often recovery responses showed varied degrees of time-lag. Overall, these findings suggest that large-scale manipulations in deer density are a viable management plan to promote community recovery following long-term deer overabundance. However, the recovery process can quickly be reversed if deer density rises, so consistent management policies are required to see long-term change.

Master of Science, University of Toledo, 2022, Biology (Ecology)

Atmospheric carbon dioxide (CO2) concentrations are increasing and may exceed 800 ppm by 2100. This is increasing global mean temperatures and the frequency and severity of heatwaves. Recently, it was shown for the first time that the combination of chronic warming and elevated carbon dioxide (eCO2) caused extreme upward bending during growth (i.e., hyponasty) of leaflets and leaf stems (petioles) in tomato (Solanum lycopersicum), which reduced growth. However, that study examined only two levels of CO2 (400, 700 ppm) and temperature (30, 37oC) at the young vegetative plant stage. Further, they did not investigate underlying mechanisms for this warming + eCO2-induced hyponasty, which is likely to involve the plant hormones auxin and ethylene, based on their role in thermal hyponasty. In this study, warming + eCO2 hyponasty was evaluated in tomato across a range of temperatures and CO2 concentrations, and at multiple life stages. Ethylene tomato mutants were examined to explore the potential role of these hormones in warming + eCO2 hyponasty. Lastly, other species were examined to test the hypothesis that warming + eCO2 hyponasty is restricted to compound-leaved species in this family. At eCO2 (800 ppm), petiole angle increased ca. linearly as temperature increased from 30-38oC. Under heat stress (HS, 38°C), petiole angle increased at all eCO2 concentrations compared to ambient (600/800/1000 vs. 400 ppm). All life stages examined (juvenile, pre-reproductive, and flowering) had increased petiole angle in leaves developed during warming + eCO2, such that most leaves exhibited hyponasty in juvenile plants but only young leaves did so in adults (previously fully-developed leaves were unaffected). Ethylene-insensitive (nr) and -constitutive (epi) mutants displayed similar changes in petiole angle with warming + eCO2 compared to the non-mutant reference (cv. Celebrity), indicating that ethylene is not a main component of the mechanism of this hyponastic response. (open full item for complete abstract)

Master of Science in Environmental Science, Youngstown State University, 2022, Department of Physics, Astronomy, Geology and Environmental Sciences

Anthropogenic increases in greenhouse gases, especially carbon dioxide, have been associated with rising global temperatures. These changes have led to desertification, heat waves, ecosystem disruption, intensification of severe weather, and loss of agricultural productivity. To mitigate against these adverse effects, carbon sequestration approaches such as afforestation and reforestation are being explored in landscapes, including urban ecosystems. The amount of forest cover and carbon storage was evaluated for the Youngstown Metropolitan Area (YMA), located in northeast Ohio. Four urbanized sub-watersheds of the Mahoning River within the YMA were chosen. The amount of forest cover for each sub-watershed for the years 2001 and 2019 was determined using ArcGIS Pro and a 50- year land cover projection was generated using the TerrSet software. Results indicate that YMA lost approximately 40ha (5,330ha to 5,290ha) of forest cover between 2001 and 2019, while developed areas gained 200ha (from 18,400ha to 18,600ha) between the same period. While the Dry Run Creek is the only sub-watershed in the study area with an increased forest area (from 1,420ha in 2001 to 1,460ha in 2019), the Crab Creek sub watershed registered the highest decrease (from 1,760ha to 1,720ha) during the same period. Currently, the area under forest cover in the Crab Creek sub-watershed is the largest (1,720ha or 17.2km2 ), storing approximately 60,700t of carbon. On the other hand, the Andersons Run-Mill Creek sub-watershed has the lowest forest area 524ha (5.24km2 ), sequestering up to 18,500t of carbon. By 2069, the area under forest cover in Crab Creek is predicted to decrease by 70ha (from 1,720ha in 2019 to 1,650ha in 2069), while iv developed land area would increase by 90ha (from 3,350ha in 2019 to 3,440ha in 2069). Although 90.3% of Andersons Run-Mill Creek sub-watershed is expected to be developed by 2069, forest cover is predicted to occupy 6.9% of its landscape. This study showed (open full item for complete abstract)

Doctor of Philosophy, The Ohio State University, 2022, Environment and Natural Resources

Seed dispersal mutualisms between plants and animals often determine the structure and diversity of ecosystems. In eastern hardwood forests of North America, the mutualism between scatter-hoarding animals and nut-bearing trees is crucial in shaping the distribution of dominant tree species and the complex wildlife communities they support. Avian seed-hoarders, in particular Blue Jays (Cyanocitta cristata), are especially important long-distance dispersers of oak (Quercus) acorns and other small nuts, through their caching of seeds in the autumn for winter consumption. Since oak-dominated forests are declining across much of the eastern U.S. – through mesophication, disease, and introduced pests – understanding their relationship with jays is critical to determining how best to manage for increased oak dispersal and recruitment. In addition, the reintroduction of American chestnut (Castanea dentata) to its former range is anticipated in the near future, and jays are likely to play a key role in their natural dispersal from founder plantings. In this dissertation, I examine dynamics of the mutualism between avian seed-hoarders and oaks/chestnuts to determine how it will shape these two processes of forest change – oak decline and chestnut reintroduction. I approach this topic in two ways. First, I examine each stage of the dispersal process from selection of seeds by birds through growth and survival of seedlings, for two common oaks (white oak [Q. alba] and black oak [Q. velutina]) and American chestnut. Second, I examine the link between mast abundance and Blue Jay abundance and survival, to determine how jay populations will be influenced by oak forest declines. When assessing the seed preferences of jays and other avian seed-hoarders in southeastern Ohio (Chapter 2), I found that jays consistently preferred black oak acorns over chestnuts, and chestnuts over white oak acorns. The strength of their preference for black oak acorns increased in late fall/early wint (open full item for complete abstract)

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

Post-agricultural forests are characterized by low species diversity, structural homogeneity, and have many invasive species. These conditions present unique challenges to land managers, who are increasingly looking for ways to achieve multiple land management goals including ecosystem enhancement and the potential for moderate timber harvesting. Given these broadened goals, management options that result in less ‘intense' disturbances are increasingly sought after. Girdling is one such method that results in the slow death (3-5 years) of affected trees, whose implementation and effects upon post-agricultural forests remains undertested. At the Working Woods area in Holden Arboretum up to 20% of the canopy was girdled between 2018 and 2019. The canopy structure and growth of 457 target trees that received varying amounts of nearby girdling were measured from 2018 through the end of 2020. To assess canopy structure, hemispherical photos were used to provide a measure of canopy openness around the target tree, and a LI-COR LAI 2200C was used to measure both Leaf Area Index (LAI) and Diffuse Non-Interceptance (DIFN). Canopy structure metrics were assessed in a mixed effect model that showed the presence of girdling treatment and time since girdling appeared to only marginally influence LAI measurements. Growth was assessed with both yearly diameter at breast height (dbh) and weekly dendrometer band window increment measurements. Growth was assessed in several growth periods consisting of pre-treatment growth, post-treatment growth, and the overall growth throughout the experiment. Pre-treatment growth was assessed through linear regression and ANOVA models that found it to be very dependent on initial size and species. Post treatment growth in similar models showed that initial size is still important, but species trends results in inconsistent growth rates as elm trees were the only species to exhibit greater growth rates with increased nearby girdling. The (open full item for complete abstract)

Ph.D., Antioch University, 2021, Antioch New England: Environmental Studies

White pine blister rust (WPBR) has been affecting New Hampshire's white pines for more than a century, yet no data exist on the long-term effects of the non-native disease on the state's forests, particularly with respect to the regeneration and sustainability of white pine, and forest succession. This study aimed to address the gaps in the literature by exploring: 1) the current distribution, incidence, and severity of WPBR in New Hampshire; 2) the application of two historical hazard ratings models, one climatic, and one biotic; and 3) the long-term effects of the disease on forest composition, structure, and succession. Historical blister rust maps were used to select research sites for a comparison between pine stands that had blister rust, and pine stands that were infection-free when mapped (1929-1976) by the NH Blister Rust Control Program. One hundred sites in 50 towns were revisited in the spring of 2018. This research included the development and application of: 1) a WPBR canker severity index for white pine; 2) a disease-disturbance model for WPBR; and 3) a forest succession trajectory for forests disturbed by WPBR. Results suggested that 1) WPBR incidence had increased since a 1998 statewide study; 2) native Ribes populations were well-distributed throughout the state; 3) Ribes that infected white pines were less likely to be within the historical 300-yard protection zone; 4) the historical hazard models were outdated, particularly in relation to New Hampshire's climate; and 5) WPBR can aid natural successional processes to influence forest structure and succession. This research connected historical data with the present to improve our understanding of the relationship between WPBR and forest succession in a changing climate. During this process, several knowledge gaps were identified for future research.