Bachelor of Science, Wittenberg University, 2023, Biology

Species diversity has become of more importance to ecological community surveys and conservation efforts globally. Use of such methods of assessing species in target groups of particular concern, such as herpetofauna, have increased in frequency in recent decades, incorporating mathematical indices and measures in an attempt to analyze community composition as a trend over time. The goal of this study was to report herpetofauna species found in the region, their diversity, dominance and rarity, richness, and other measures throughout the four separate survey trips, showing trends over the periods of time in order to better inform the timing and methods of the survey in future years. Ex-situ data analysis of the detections over four years thus far have found 86 herpetofauna individuals across 26 distinct species. Reptilian species make up the larger portion of detections than amphibian, with a ratio of detections and relative abundance of 1.39:1, respectively. Dominant species across trip years included the southern two-lined salamander, the southern cricket frog, and the little brown skink. Dominant species across seasons included the Mississippi slimy salamander, southern cricket frog, and little brown skink. Highest herpetofauna abundance was found in 2018 and in the fall season, while highest species richness was detected in 2018 and in the spring season. Species evenness was maximized in 2019 and in the fall season. Shannon-Weiner and Simpson's Diversity were both maximized in the 2018 and spring trips and lowest in the 2021 and fall trips overall. Diversity of amphibians in particular was maximized in 2022 and in fall, while diversity of reptiles in particular was maximized in 2018 and in spring season. Reptiles were detected at higher average substrate temperatures and similar air temperatures to amphibians. The highest and lowest temperatures at detection for amphibians were lower than those for reptiles when adjusting for the summer season anomaly found. Dev (open full item for complete abstract)

Committee: Richard Phillips (Advisor); Adam Parker (Committee Member); John Ritter (Committee Member) Subjects: Animal Sciences; Animals; Biology; Ecology; Environmental Science; Environmental Studies; Wildlife Conservation; Wildlife Management; Zoology

Doctor of Philosophy, The Ohio State University, 2012, Environment and Natural Resources

In an era of rapid ecological change due to loss of biodiversity, climate change, and altered nutrient dynamics, predicting ecosystem dynamics and maintaining ecosystem services provided by complex natural ecosystems is an increasing concern. Novel disturbances, including those caused by invasive insects, provide an unfortunate opportunity to test the applicability of ecological theories to practical problems. One such case study is the loss of eastern hemlock (Tsuga canadensis, hemlock) from much of eastern North America due to the invasive pest hemlock woolly adelgid (Adelges tsugae; HWA). Foundation species such as hemlock are abundant and define the ecosystem processes of a community through a small number of strong interactions. As these interactions are lost, ecosystems are predicted to transition rapidly and develop distinctly different energy exchanges, nutrient cycles, and compositions that define a new community state. Much of the understanding of such transitions is conceptual. To advance the understanding of the function of foundation species and transitions to alternate community states when a foundation species is lost, my dissertation examines vegetation community composition and ecosystem function in 38 hemlock-dominated riparian forests across the central Appalachians. On the unglaciated Allegheny Plateau in Ohio, uninvaded forests provide baseline data on hemlock as a foundation species. Across West Virginia and Virginia, sites impacted by HWA for 9-32 years were selected as a chronosequence to compare changes in compostion and function. Hemlock forests exhibit low species richness, and thus have low resiliency. In uninvaded forests of Ohio, hemlock dominates the vegetation, although other species are structured by environmental gradients. Structural equation modeling indicates hemlock has a negative influence on vegetation species richness, light availability and productivity. Thus, a likely future HWA arrival will result in a complete reorganiz (open full item for complete abstract)

Committee: P. Charles Goebel PhD (Advisor); John Cardina PhD (Committee Member); Peter Curtis PhD (Committee Member); Ronald Hendrick PhD (Committee Member) Subjects: Ecology; Environmental Science; Forestry

Doctor of Philosophy, The Ohio State University, 2007, Evolution, Ecology, and Organismal Biology

Nitrogen (N) is the nutrient most limiting to plant growth (NPP) in temperate forests. In N-limited temperate forests, most of the N required for NPP is recycled between soil and plant N pools by the microbial process of N-mineralization (Nmin). However, human activities have increased atmospheric N deposition (Ndep) to forests in the last 50-100 years, and this surplus N may increase NPP. But, forest responses to Ndep are not satisfactorily understood, and depend on how atmospheric N inputs are partitioned between soils and plants. From my field data collection at a mature forest site, I estimated that NPP required 51 kg N ha-1 yr-1, most of which was used for fine root and leaf production (62% and 31%, respectively). Each year, Nmin supplied 87% of Nreq, and Ndep contributed an additional 13%, 4% of which was due to canopy retention of Ndep (Ncr). Data from my mesocosm 15N-labelling experiment suggested that very little (<10%) of Ncr observed in the field was actually taken up by trees, and the majority of Ndep (>85%) was assimilated into soil pools. These results suggest that Ndep could not have significantly increased forest NPP at UMBS over the time scale of my studies. My greenhouse experiment corroborated this conclusion, with tree seedlings showing no significant increase in photosynthesis or growth in response to Ndep at ambient rates. However, Ndep to forest ecosystems has been occurring for decades in industrialized regions, and most of the N inputs have been incorporated into soil organic matter (SOM). Research across temperate forests has suggested that forests exposed to large N inputs over time exhibit decreased soil C/N ratios, which are associated with faster Nmin rates. Using meta-analysis, I verified this pattern in the literature, and discovered novel relationships between forest soil properties and their responses to N inputs. My results demonstrated a long-term, quantitative relationship between Ndep and Nmin, and suggest that NPP may increase (open full item for complete abstract)

Committee: Peter Curtis (Advisor) Subjects: Biology, Ecology

Doctor of Philosophy, The Ohio State University, 2005, Natural Resources

In created and restored wetlands, hydrology and time play an important role in regulating ecological processes including productivity and soil development. The influence of hydrology was examined using full-scale wetlands and replicated mesocosm tubs at the Olentangy River Wetland Research Park (ORWRP). In one study, twenty mesocosms were planted with either one of two wetland plants common to the region and subjected to either a pulsed or steady-flow hydrology. No significant differences in nutrient concentrations, uptake or uptake efficiency were detected among species groups; however hydrology did influence plant tissue N:P ratios. A second project evaluated the restoration of flood pulses on a 5.2-ha bottomland forest along the Olentangy River at the ORWRP. In June 2000, the bottomland was restored to approximate natural flooding by cutting three breeches in an artificial levee along the north section of the forest and a fourth breech along the riverbank of the south section. Productivity in 2004 at the north section was substantially higher than a previous aboveground productivity estimate conducted before restoration. Relationships between flood frequency and canopy basal growth over 15 years were also detected. In a separate study, soil development over time was evaluated in two marshes that were created in non-hydric soils at the ORWRP in 1994. In May 2004, soil samples were collected and compared to samples collected in 1993 (after the wetland basins were excavated but prior to flooding) and 1995 (18 months after the wetlands were flooded). Soils in the two wetlands have changed substantially through sedimentation and organic accretion, and mean percent organic matter at the surface has increased from 5.3 ±0.1% in 1993 to 9.5 ±0.2% in 2004. Spatial analyses showed that soil conditions have also become increasingly more variable. Higher sediment accumulation was detected in the deeper open water zones than in the emergent vegetation zones. Directional spatia (open full item for complete abstract)

Committee: William Mitsch (Advisor) Subjects: