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)

Committee: Thomas Crist (Advisor); Henry Stevens (Committee Member); Melany Fisk (Committee Member); Mary Henry (Committee Member); Jing Zhang (Committee Member) Subjects: Ecology; Entomology; Forestry

Ph.D., Antioch University, 2020, Antioch New England: Environmental Studies

The overall goal of this study was to evaluate whether coastal Maine (USA) forests are resilient to changing climate and fire regimes. The occurrence of a catastrophic wildfire at Acadia National Park (ANP) in 1947 provided a unique opportunity to examine the impacts of wildfire on forest dynamics in upland communities of coastal spruce-fir and northern hardwood forests of the Maine coast. This study, conducted 68 years after the stand-replacing 1947 Bar Harbor Fire, builds on studies by W.A. Patterson conducted in 1980 and 1992-1994, 33 and 45-47 years after the fire. There were two lines of investigation in this study: vegetation change following a large-scale, stand-replacing wildfire; and an assessment of wildfire risk following a long period with no major disturbance. In 2016 I quantified and characterized stand and site characteristics including: basal area and stem density of woody species; aboveground biomass and necromass of trees, saplings, and shrubs; dead downed woody fuel loads; duff depth; fuel height; soil depth to bedrock, and canopy closure for 23 stands throughout ANP. To evaluate long-term trends in post-fire recovery, I compared 2016 forest composition, structure and fuel loading data with that in 1980 and 1992-94. I mapped current wildfire risk to aid managers in identifying where mitigation practices would be most effective in reducing fire risk. I used an ArcGIS model that extends field data of current fuel conditions and spatially portrays wildfire risk across the landscape. Mixed effects models were used to determine the best remotely sensed numeric biomass data as a predictor of biomass and necromass measured on the ground. Widespread regeneration of red spruce following the initial establishment of aspen and birch suggests that forests of ANP are resilient to wildfire. Stands that did not burn in 1947 remain as mature-to-overmature spruce and fir. Biomass and necromass is continuting to accumulate. Fuel loads are generally high to very hig (open full item for complete abstract)

Committee: Peter Palmiotto D.F. (Committee Chair); William Patterson Ph.D. (Committee Member); Rachel Thiet Ph.D. (Committee Member) Subjects: Ecology; Environmental Studies; Forestry; Natural Resource Management; Paleoecology

Doctor of Philosophy, The Ohio State University, 2016, Entomology

Disturbances alter habitat structure, energy and nutrient flow, and species composition in ecosystems, thereby shaping patterns in community dynamics and ecosystem processes over time. In forests of eastern North America, natural disturbances (e.g. fire, wind, insect and disease outbreaks) create a mosaic of differently aged habitat patches that maintain structural complexity at multiple spatial scales through the creation of biological legacies such as standing and downed woody debris and patches of understory vegetation intertwined with undisturbed forest. Anthropogenic disturbances (e.g. exotic species, land-use change, management practices) may alter the abundance or spatial patterns of these important structural features in the landscape, potentially impacting forest communities such as populations of ground-dwelling invertebrates. Ground-dwelling invertebrates are abundant in forest ecosystems, and their responses to natural and anthropogenic disturbances have significant implications for ecosystem services such as decomposition and nutrient cycling. Therefore, the overarching goals of this dissertation research were to evaluate the effects of disturbance to the forest canopy and understory on the ground-dwelling invertebrate community. Objectives of this research were to investigate the impacts of tree mortality caused by disturbances characterized by different properties on invertebrate diversity, community composition, and dispersal potential. Three dynamic models were proposed (Chapter 1) to describe the temporal relationships in the magnitude effects of canopy gap formation, accumulation (and removal) of coarse woody debris, and soil disturbance caused by the exotic emerald ash borer (Agrilus planipennis Fairemaire) (Chapters 2-4), wind, and salvage logging (Chapter 9) on ground-dwelling invertebrate communities. Canopy and understory vegetation disturbances that typically occur simultaneously when trees die were decoupled via a manipulative experim (open full item for complete abstract)

Committee: Daniel Herms (Advisor) Subjects: Ecology; Entomology

Doctor of Philosophy, The Ohio State University, 2012, Evolution, Ecology and Organismal Biology

At the University of Michigan Biological Station (UMBS) in northern lower Michigan, USA, I employed a combination of chronosequence observations and experimental forest manipulation to evaluate the potential of partial forest disturbances to facilitate resilience of carbon (C) storage over two centuries of succession. In 2008, I assisted in initiation of the Forest Accelerated Succession ExperimenT (FASET). All aspen and birch trees in the treatment area were stem girdled to induce mortality. I used lysimeters to characterize nitrogen (N) leaching losses from soil in response to widespread tree mortality. N export was significantly greater in treated than control stands and corresponded to increased fine roots mortality, but total N export was insufficient to limit long-term C storage rates in affected stands. From 2008 through 2011, I used a portable canopy LiDAR (PCL) system to monitor canopy structural changes following widespread mortality in FASET. I also measured leaf-level maximum C assimilation (Amax) rates in canopy co-dominant red oak, red maple, and white pine to evaluate physiological consequences of aspen and birch senescence. Canopies became shorter, more open, and more heterogeneous over time in canopies of treated but not control stands. Leaf Amax of successor canopy species did not change in response to canopy structural rearrangements or increased N availability. I also used the PCL system to characterize canopy structure in stands spanning two centuries of succession. I define a novel metric of canopy structural complexity: rugosity. Rugosity increased with stand age in and explained more variation in aboveground C storage than other known drivers of forest C storage. Forests with more structurally complex canopies used light and nitrogen resources more efficiently than forests with structurally simpler canopies. I present evidence of a mechanistic linkage between canopy structure and forest function that allows aging forests to maintain higher t (open full item for complete abstract)

Committee: Peter Curtis (Advisor); Gil Bohrer (Committee Member); James Bauer (Committee Member); Charles Goebel (Committee Member); Kathleen Knight (Committee Member) Subjects: Biogeochemistry; Biology; Ecology; Environmental Science; Forestry

Doctor of Philosophy (PhD), Ohio University, 2001, Plant Biology (Arts and Sciences)

Introduction of non-native species is the oldest form of human-induced global change. From the exchange of agricultural crops and domestic animals, to the accidental introduction of weeds and microbes, non-native species have been incorporated into the floras and faunas of all continents and most oceanic islands. These organisms can have marked effects on ecosystems. I wanted to address the following facets of non-native species invasion: (1) What characteristics of ecosystems make them more susceptible to non-native species invasion? and (2) What characteristics of the invader allow invasion? To address these questions, I used a gradient of anthropogenic disturbance common in southeastern Ohio forests: intact secondary forest, forest edge, and aggrading clear cuts. Paulownia tomentosa is a tree native to Asia and thought to have been introduced to North America in the 1840's. The species has naturalized throughout Appalachia. I studied the growth, allocation, establishment, and seed persistence across habitats. I also became interested in the basic ecology of P. tomentosa, particularly the ability of the species to resprout and phenotypic plasticity in naturalized populations. The most important factors in determining the invasive potential of P. tomentosa were disturbance and herbivory. Paulownia tomentosa is an early successional species that can grow rapidly under high light conditions. Seed ecology suggests that the species can form a persistent seed bank. However, light is required for germination and seeds responded positively to soil disturbance. Large gaps may be sufficient to allow seeds in the seed bank to germinate and grow to the canopy. However, the species is very susceptible to herbivory. Plants had to be protected from mammals in order to persist. Even though above- and below-ground competition affected plant growth and allocation, it did not affect the overall success of plants. Paulownia tomentosa can resprout at an early age and initially invests (open full item for complete abstract)

Committee: Brian McCarthy (Advisor) Subjects:

Master of Science (MS), Ohio University, 2006, Plant Biology (Arts and Sciences)

The effects of common forest management practices (burning and thinning) on the seed bank are assessed. Species composition of the soil seed bank is examined under three treatments: thin, burn, thin followed by burning, and an untreated control. Thinning was conducted in Fall 2000 and burns were conducted in Spring 2001. Soil samples were collected in March 2004, 3 years following treatment. Species composition is assessed by seedling emergence. Seventy total species are found in the seed bank. Ruderal species such as Erechtites hieraciifolia (L.) Raf., Carex spp., and Rubus spp. are the most commonly occurring species across all treatments. No significant difference in species composition or proportion of functional groups is found between any of the treatment groups. Species composition of the seed bank and above-ground vegetation are significantly different in all treatments. Species composition and canopy cover are each significantly spatially autocorrelated in the thinned and burned treatment.

Committee: Brian McCarthy (Advisor) Subjects: