Master of Science (MS), Wright State University, 2018, Biological Sciences

Macroinvertebrates are important contributors to wetland ecosystems due to their role in decomposition, nutrient cycling, and as a food resource for other organisms. Several studies have analyzed the macroinvertebrate communities in created wetlands, but few have evaluated them in the context of trophic structure in both created and natural wetlands. The objective of this study is to better understand benthic macroinvertebrate community composition and trophic structure in created and natural wetlands. My central hypotheses were that macroinvertebrate communities in created wetlands would have (1) differing composition and (2) less complex trophic structure with shorter food-chain length compared to natural wetlands. Macroinvertebrates and soil cores were collected from five created and two natural depressional marshes. I assessed macroinvertebrate community characteristics such as diversity and composition, and functional feeding group composition. I used stable isotope analysis to determine food-chain length and other trophic metrics. Soil cores were used to determine bulk density, texture, and the C:N profile of the soil in the wetlands. Through a combination of univariate (e.g. ANOVA) and multivariate analyses (e.g. NMDS, PERMANOVA) these conclusions were met: (1) Macroinvertebrate taxa composition differed statistically between wetland types (p= 0.05); (2) FCL did not differ significantly between wetland types. In addition, functional feeding group composition was trending toward significance (p = 0.095), and soils were found to be distinct between wetland types (p= 0.043), with bulk density being a strong driver of that relationship (p= 0.012). These results show that in these wetlands, macroinvertebrate species present are different, however the overall function they provide are very similar between wetland types. The habitat characteristics in created wetlands that are known to quickly develop (e.g. plant community composition) were similar to the natural we (open full item for complete abstract)

Committee: Katie Hossler Ph.D. (Advisor); Yvonne Vadeboncoeur Ph.D. (Committee Member); Volker Bahn Ph.D. (Committee Member); John Stireman Ph.D. (Other) Subjects: Ecology; Entomology; Environmental Science; Environmental Studies

Doctor of Philosophy, The Ohio State University, 2014, Environment and Natural Resources

In recent years, a holistic ecosystem conceptualization has emerged that structurally and functionally links the river, and its riparian and floodplain zones into an integrated ecological unit - the riverine landscape. The riverine landscape often exhibit lotic water-driven disturbance biophysical complexity (e.g., patchiness) over both fine and broad spatio-temporal scales. However, despite the well-documented importance of river corridors (e.g., as biological refuges in human-modified landscapes), the role of riverine landscape pattern and composition on ecosystem structure and function is largely unknown. This study investigated the influence of internal (river size, lateral flow connectivity) and external (catchment land use and land cover) factors on site-specific riverine landscape patterns. It then used riparian spiders of the family Tetragnathidae and ants as model organisms to explore the associations between internal riverine landscape patchiness and the distribution, diversity, and trophic dynamics [e.g., trophic position (TP), and dependency on aquatically derived carbon (CA)]. Riverine landscape patchiness was measured using a combination of field (vegetation surveys, canopy photography, shoreline habitat measurements) and remote-sensing approaches [e.g., using a GIS, aerial photos, and Light Detection and Ranging (LiDAR) data]. Ants and spiders were surveyed on each side of the river at each study reach. A suite of analytical methods were used including Analysis of Variance (ANOVA), linear regression, Principal Component Analysis (PCA), Maximum Entropy (MaxEnt) modeling, a model-selection approach using Akaike Information Criterion (AIC) and Non-Metric Multidimensional Scaling (NMDS). Results indicate that both external and internal factors were associated with riverine landscape pattern (patch area and shape and size) including drainage area (a proxy for ecosystem size), proximity to impoundment (a proxy for lateral flow connectivity), and catchm (open full item for complete abstract)

Committee: Mazeika Sullivan Dr. (Advisor); Charles Goebel Dr. (Committee Member); Desheng Liu Dr. (Committee Member) Subjects: Ecology; Environmental Management

Master of Science (MS), Wright State University, 2009, Biological Sciences

The widespread removal of large carnivores from terrestrial ecosystems may be contributing to plant species loss and biotic homogenization through trophic cascades. A few plants not preferred by ungulates are increasing in abundance while the majority of preferred plants are in decline. A meta-analysis of recruitment gaps in browse-sensitive tree species demonstrated that failed recruitment coincided in time with carnivore loss. In all studies recruitment continued in nearby browsing refugia. A second meta-analysis revealed that the mechanism of mammalian herbivore-mediated trophic cascades contains a behavioral component. Foraging mammals exhibited higher giving-up densities (GUDs) when under higher predation risk. GUDs were highest in microhabitats perceived to be risky when predators were present, intermediate in safe microhabitats when predators were present, and lowest in safe and risky microhabitats in the absence of predators. Removing the landscape of fear may decrease spatial heterogeneity in plant communities, contributing to biotic homogenization.

Committee: Thomas P. Rooney PhD (Advisor); Yvonne M. Vadeboncoeur PhD (Committee Member); John O. Stireman III PhD (Committee Member) Subjects: Biology; Ecology