Master of Science (MS), Ohio University, 2019, Plant Biology (Arts and Sciences)

Masting is a reproductive strategy in plants characterized by high interannual variability in seed production, in which individuals in the population synchronize their reproductive effort. Both weather and resources have been found to drive the frequency and intensity of masting events; however the responses appear to be regionally- and species-specific. To analyze how weather, resources, and masting influence chestnut oak and black oak reproduction at the population-level, I used an 18-year acorn production dataset from the Fire and Fire Surrogate study. Results showed that silvicultural treatments (i.e., resource manipulation) increased acorn production in chestnut oak, compared to the control. Acorn production in black oak was not significantly affected by silvicultural treatments; however, there was an increase in reproduction the year after a prescribed fire. Weather also had a significant impact on oak reproduction. Chestnut oak acorn production had a positive relationship with both spring and summer temperatures, while black oak acorn production had a negative relationship with the date of the last spring frost. I then examined differences in reproductive effort and variability at the individual-level, using a variety of tree-level and environmental characteristics. Results showed that growth rate and placement on the landscape were important for both chestnut oak and black oak reproductive effort and variability, while soil conditions were important for black oak only. Intraspecific variability was predominately influenced by tree-level characteristics, with higher growth rates separating super and poor producers for both chestnut oak and black oak. Growth-reproduction trade-offs were only observed for black oak super producers. Determining the factors that influence masting events at both the population- and individual-levels has important implications for predicting climate change impacts, and subsequent changes in food resources for wildlife and forest tr (open full item for complete abstract)

Committee: Rebecca Snell (Advisor); Brian McCarthy (Committee Member); David Rosenthal (Committee Member) Subjects: Botany; Ecology; Environmental Science; Forestry; 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

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, 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