Master of Science (MS), Wright State University, 2021, Earth and Environmental Sciences

The non-native invasive shrub Amur honeysuckle, Lonicera maackii (Rupr.) Herder (Gorchov and Trisel, 2003), is one of the most prolific invasive plant species across Midwestern and Northeastern landscapes of the United States. The locations of 2,095 individual Amur honeysuckle stems were geolocated using handheld GPS units in the understory of mixed growth forests at two study sites located approximately 5 km apart in northwestern Greene County, OH. Each site has undergone different levels of anthropogenic disturbance through time. The stem position data was used to measure the spatial clumping distribution and the density of Amur honeysuckle. The spatial clumping of Amur honeysuckle stems was measured using the fractal box counting method at each study site without regard for streams, trails, or elevation. The density of Amur honeysuckle (number of stems per square meter) was measured in zones as a function of the horizontal distance perpendicular to the edge of streams, trails, and within elevation (area between contour lines). Amur honeysuckle density is found to be uncorrelated with its proximity to streams, trails, and elevation. The density of Amur honeysuckle as a function of distance from streams and trails does not reveal an edge effect. The fractal dimension (scaling exponent) was computed to be ~1.5 at each of the two sites which means that the spatial clustering is the same for actively managed (partial Amur honeysuckle removal) and unmanaged sites. These results suggest that the invasion potential of Amur honeysuckle is robust, and its distribution may not be constrained in riparian forests by the variables included in this study.

Committee: Christopher Barton Ph.D. (Advisor); David Peterman Ph.D. (Committee Member); Ryan McEwan Ph.D. (Committee Member) Subjects: Biology; Earth; Ecology; Environmental Science

Doctor of Philosophy, The Ohio State University, 2021, Environment and Natural Resources

Biological invasions threaten biodiversity and ecosystem functions. Stream ecosystems and their adjacent riparian zones are connected via a complex network of direct and indirect linkages, presenting a unique setting for the study of invasion. I investigated the effects of two different riparian invaders on stream biota and stream-riparian trophic linkages: an invasive insect (hemlock woolly adelgid Adelges tsugae; hereafter HWA) and an invasive shrub (bush honeysuckles Lonicera maackii and L. tatarica). Both sets of studies used the same basic approach at >20 streams across a gradient of invasion intensity: record geomorphology and water chemistry, collect and assess in-stream biota, quantify reciprocal subsidies, and determine riparian spider density, relative reliance on aquatically-derived energy (i.e., nutritional subsidies originating from periphyton), and invertebrate food-chain length (using naturally-abundant stable isotopes) at each study reach. I also conducted a before-after, control-impact (BACI design) honeysuckle removal experiment. My results suggest that in-stream physical and chemical alterations (i.e., large-wood characteristics and nutrient concentrations) associated with HWA invasion and subsequent hemlock decline drove changes in stream invertebrate diversity and trophic relationships. Evidence for ecological consequences of this invader was strongest at lower trophic levels. For example, periphyton biomass was greater at uninvaded reference sites than at severely invaded sites (x = 1.37 vs 0.52 mg cm-2), while relative abundance of herbivorous macroinvertebrates increased from 4 to 23% at the severely invaded sites. Spider (family Tetragnathidae) densities were 3.2 times higher at sites with severe hemlock decline and although density was not linked to emergent insect density overall, δ15N signatures of Araneidae and Pisauridae spider families tracked emergent insect δ15N (r2 = 0.42 and 0.78, respectively), suggesting a trophic linkage. (open full item for complete abstract)

Committee: S. Mazeika Sullivan (Advisor); Lauren Pintor (Committee Member); P. Charles Goebel (Committee Member) Subjects: Ecology; Environmental Science; Freshwater Ecology

Doctor of Philosophy, Miami University, 2020, Ecology, Evolution and Environmental Biology

This dissertation examines how an invasive woody plant, Lonicera maackii, temporally and spatially structures native bee communities of forest-edge habitat in agricultural landscapes. In Chapter 1, I measured bee species composition and pollination services ≤200 m from isolated forest patches in response to L. maackii flower removals. Removing flowers released a subset of small-bodied bees and increased pollination services after two years. Pollination services provisioned by large-bodied and generalist bee species (e.g. Bombus spp) increased when nearby plants were adjacent to intact L. maackii flowers. Findings suggest that L. maackii flowers suppress one component of the bee community and attract another to the forest patch that increases usage of the adjacent crop fields. In Chapter 2, I compared two components of the bee community and their responses to L. maackii density, floral resources of the forest patch, and the surrounding landscape. Bees sampled in pan traps were typically small, specialized, and responded to local patch features. Bees sampled in vane traps were larger in body size, social, and responded to landscape composition 3 km from the forest patch. These findings suggest that L. maackii floral resources support weaker foragers within the forest patch as well as larger bees that forage throughout the landscape. Both components of the bee community responded to tree community composition and were vertically stratified in the tree canopy. In Chapter 3, I measured bee diversity and community composition at different vertical strata in response to L. maackii density and flowering period as well as floral resource availability of woody plants. I found that L. maackii supports a component of the vertically stratified bee community which changes interactions with floral resources of the native woody vegetation at different vertical strata. Collectively, my studies demonstrate that L. maackii structures forest-edge bee communities through mechanisms invo (open full item for complete abstract)

Committee: Thomas Crist (Advisor); David Berg (Committee Member); Amelie Davis (Committee Member); David Gorchov (Committee Member); Jign Zhang (Committee Member) Subjects: Agriculture; Biology; Conservation; Ecology

Master of Science in Botany, Miami University, 2019, Biology

The secondary-growth hardwood forest of Rush Run Wildlife Area (RRWA), Preble County, Ohio was studied 54 years after an initial study was conducted in 1964. Although Dutch elm disease (DED) was likely present in the area by the late 1930s to early 1940s, American elm (Ulmus americana L.) was recorded as one of the dominant canopy species (avg. relative density = 15.1%) and subcanopy species (9.0%) in 1964. Seedlings of American elm were also noted to be abundant across RRWA. Of the 17 plots used in 1964, 10 were chosen based on the previously recorded high relative density of American elm and resurveyed. By 2018, American elm was absent from the canopy, subcanopy, and seedling layers. A secondary analysis of measurements taken in 2018 that included dead standing Fraxinus spp. showed that the current loss of ash was extensive but non-impactful upon other species. Findings oppose the previous predictions that American elm can persist indefinitely in forest stands following introduction of DED but restricted to subcanopy and smaller stature. It is possible that previous studies have not allowed adequate time after introduction of DED to accurately assess the effects on American elm.

Committee: Michael Vincent PhD (Advisor); Richard Moore PhD (Committee Member); David Gorchov PhD (Committee Member) Subjects: Botany; Ecology; Plant Sciences

Master of Science (M.S.), University of Dayton, 2017, Biology

Terrestrial-to-aquatic linkages are an important vector for the transfer of nutrients from one habitat to another. Therefore, the biology of headwater streams is strongly influenced by the surrounding terrestrial riparian vegetation. Amur honeysuckle (Lonicera maackii) is an invasive shrub that thrives in disrupted habitats including stream riparian zones. Although, extensive research has shown the detrimental effects of L. maackii on terrestrial systems, little research has been done on how cross boundary subsidies such as leaves and woody debris are impacted by the dense and often overarching L. maackii invasion in headwater stream riparian zones. Therefore, the aim of this study is to understand the influence of a gradient of L. maackii density in riparian habitats on the contribution of organic subsidies in stream systems in Southwestern Ohio. Across the established gradient of L. maackii invasion leaf litter biomass, fruit biomass, falling twig biomass, terrestrial and aquatic fine woody debris (0.5-9.9 cm diameter) volume and count, and terrestrial and aquatic coarse woody debris (>9.9cm diameter) volume were accessed. We hypothesized that sites with a higher density of L. maackii would have a decreased total leaf litter biomass deposition due to the dense overarching riparian L. maackii over the stream increasing the potential of litter getting caught in the canopy. Additionally, based on the intentionally established gradient of sites we also expected L. maackii leaf biomass to increase as invasion intensity increased. Lastly, we hypothesized that woody biomass in the form of both fine and coarse woody debris would decrease along the invasion gradient due to the dense shrub architecture. The only significant treatment effects in regards to site were found for L. maackii only leaf litter biomass (p = <0.0001), count of aquatic fine woody debris (p = 0.03292), and fruit biomass (p = 0.00597). In all cases the observed treatment effect did not follow our hypot (open full item for complete abstract)

Committee: Ryan McEwan Ph.D. (Committee Chair); Albert Burky Ph.D. (Committee Member); Mark Nielsen Ph.D. (Committee Member) Subjects: Biology; Ecology

Doctor of Philosophy, Miami University, 2016, Ecology, Evolution and Environmental Biology

While invasive plants and generalist herbivores have negative direct effects on plant communities, their indirect and interactive effects have received far less focus. I address the effects of an abundant herbivore, White-tailed deer (Odocoileus virginanus), and the invasive shrub Amur honeysuckle (Lonicera maackii) on forest plant communities, focusing on determining whether their interactions are synergistic, antagonistic, or additive. Within the Miami University Natural Areas, I sampled plant species richness and cover in five 20 x 20 m2 deer exclosures and paired controls, each with L. maackii removed from half of the plot. I found antagonistic interactions of L. maackii and deer on the tree seedling cover, suggesting that L. maackii mitigates the negative effect of deer on trees, facilitating tree survival and growth. To investigate whether L. maackii provides a refuge for tree seedlings from deer browse, I planted tree seedlings under and away from the L. maackii canopy, with and without deer exclosures, and measured their growth, survival and browse status. I found facilitation by L. maackii on survival and leaf count of Acer saccharum seedlings: where deer had access, seedlings planted under L. maackii had higher survival and more leaves. This suggests that L. maackii serves as a refuge for tree seedlings from deer browse. Finally, I explored the direct effects of deer on L. maackii, addressing whether deer browse on L. maackii is sufficient to reduce its cover. In the 20 x 20 m2 plots I scored leaf frequency of L. maackii in the height ranges browsed by deer, as well as basal area (BA) of all stems of L. maackii. I found access to deer strongly reduced L. maackii leaf frequency within the height range of deer browse, and modestly reduced BA growth. This suggests that deer affect the architecture of L. maackii more than its growth. These results indicate that considering interactive effects is fundamental to understanding the roles of thes (open full item for complete abstract)

Committee: David Gorchov (Advisor); M. Henry Stevens (Committee Member); Melany Fisk (Committee Member); R. James Hickey (Committee Member); Thomas Crist (Committee Member) Subjects: Biology; Botany; Ecology

Master of Science (MS), Ohio University, 2015, Plant Biology (Arts and Sciences)

Since the loss of Castanea dentata (American chestnut) from eastern hardwood forests, invasive species have occupied many of the forests where chestnut once resided. Even though agencies have begun to replant hybrid chestnuts into the forests, no one has examined how invasive species might interact with American chestnut. In this study, allelopathic impacts on chestnut were mimicked by adding aqueous extracts or biomass of three allelopathic invasive species tree of heaven (Ailanthus altissima (Mill.) Swingle), garlic mustard (Alliaria petiolata (M.Bieb.) Cavara and Grande), and Amur honeysuckle (Lonicera maackii ( Rupr. ) Maxim.)) to soils supporting chestnut seedlings. In greenhouse experiments, chestnut seeds were treated weekly with aqueous extracts of biomass from the invasives. Chestnut seedlings were also planted in gardens and treated with root or shoot biomass from the invasives. Finally, chestnut seedlings were planted in a forest at sites with garlic mustard present and at sites where garlic mustard had been regularly removed for 8 yrs. Growth factors of chestnut, such as height, mass, and basal area, were measured. Chestnut seedlings treated with tree of heaven extracts had lower heights and more re-sprouts than the control groups. However, results were not consistent among the experiments. Chestnut seedlings treated with some invasive plant biomass, including tree of heaven biomass, had heights statistically similar to the control groups. When treated with roots of garlic mustard, chestnut heights were statistically lower than the negative control. Chestnut seedlings planted in garlic mustard plots in the forest were only statistically taller the first time they were measured, but were not statistically different thereafter. The results from these initial experiments suggest that the allelopathic effects from tree of heaven may negatively impact reintroduction of American chestnut; however, other invasives may be less problematic.

Committee: Brian McCarthy Dr. (Advisor); Jared Deforest Dr. (Committee Member); David Rosenthal Dr. (Committee Chair) Subjects: Ecology; Plant Biology

Master of Science, Miami University, 2013, Botany

I tested whether the invasive shrub Lonicera maackii (Amur honeysuckle) competes with tree seedlings for water by either of two mechanisms: 1) intercepting rainwater during light rain events; (2) absorbing large amounts of water through its fine roots. To test the two hypothesized mechanisms I selected plots near large L. maackii shrubs and control plots away from any large L. maackii shrubs in the forest understory. Within each plot I placed a trenched and an untrenched subplot. I measured precipitation above and below L. maackii canopies, and soil water content and stomatal conductance of naturally-occurring Acer saccharum and Carya sp. seedlings in each trenched and untrenched subplot. The results somewhat supported the hypothesis that L. maackii competes with tree seedlings by interception, but were inconclusive regarding the hypothesis of competition by water uptake. A novel dataset shows that L. maackii fine roots are disproportionately common in shallow soil.

Committee: David Gorchov PhD (Advisor); Alfredo Huerta PhD (Committee Member); Melany Fisk PhD (Committee Member) Subjects: Biology; Botany; Conservation; Ecology; Plant Biology; Plant Sciences

Doctor of Philosophy, The Ohio State University, 2008, Natural Resources

Effective conservation of biodiversity in urban areas ultimately requires that ecologists understand both the patterns and mechanisms of urban-associated influences on native plant and animal communities. A neglected consequence of urbanization is the seasonal timing of life cycle events, particularly the tendency of many urban birds to breed earlier in the spring than their rural-breeding counterparts. The overall objectives of this dissertation were to (1) describe phenological and biological differences in avian reproduction in urban and rural forests, (2) identify underlying ecological mechanisms responsible for observed patterns, and (3) identify demographic consequences of phenological shifts in reproduction. First I evaluated vegetation phenology and temperature patterns, two potentially important variables influencing bird breeding phenology. There was an overall pattern of advanced phenology (e.g., bud break, leaf elongation) within species in more urban landscapes which might be associated with elevated temperatures in more urban areas. Results suggest that shifts in plant communities along the urbanization gradient, especially the increased dominance of the invasive and exotic Amur honeysuckle (Lonicera maackii) in urban forests, drove the earlier green-up of urban areas. Avian breeding phenology was also influenced by urbanization, although patterns, causes, and consequences differed between my two focal species. The non-migratory Northern Cardinal (Cardinalis cardinalis) nested earlier in urban versus rural sites, a pattern that was best explained by early spring temperatures. Contrary to findings from other studies, early-breeding cardinals apparently received no benefit in terms of survival or reproduction compared to later-breeding pairs. In contrast, the Neotropical migratory, Acadian Flycatcher (Empidonax virescens) arrived and initiated breeding later in the more urban landscapes – a phenological shift that ultimately reduced reproductive produ (open full item for complete abstract)

Committee: Amanda Rodewald (Advisor); Tomas Koontz (Committee Member); Thomas C. Grubb, Jr. (Committee Member) Subjects: Ecology

Master of Environmental Science, Miami University, 2009, Environmental Sciences

A common invasive shrub in eastern North America is Lonicera maackii; it is often controlled with mechanical and chemical methods. In this study, I evaluated the effectiveness of a new method (cut-a-major limb) to kill shrubs 2.4-4.5 m tall. I compared four treatments for efficacy and costs: all combinations of two mechanical methods– cut-a-major limb and space-cuts, with two different herbicides - Garlon 3A and Tordon RTU, in mid-November 2008 at the Ecology Research Center, Oxford, Ohio. Garlon was not effective, but Tordon killed some shrubs, and was more effective in space-cuts than when applied to a major limb. Treating one stem was not effective in killing multi-stemmed shrubs. Cut-a-major limb was not effective on the large shrubs used in this study. Space-cuts with Tordon was more expensive than some previously reported methods, but may be a good alternative to control single-stemmed medium-size shrubs and when spot treatment is needed.

Committee: David Gorchov (Committee Chair); Carolyn Keiffer (Committee Member); Sandra Woy-Hazleton (Committee Member) Subjects: Agricultural Chemicals; Botany; Environmental Science

Master of Science (M.S.), University of Dayton, 2013, Biology

The introduction of non-native, invasive plants has significantly reduced the biodiversity of native plants and altered ecosystem processes and successional trajectories in novel environments. The invasive shrub Amur honeysuckle (Lonicera maackii) has negatively impacted the biodiversity and ecological balance of Eastern Deciduous Forests by reducing the growth and reproduction of native forbs, tree seedlings, and overstory trees. Previous research on the competitive success of L. maackii has focused on allelopathy and competition for light and below-ground resources. However, the disruption of native mycorrhizal networks by L. maackii is one potential mechanism that has been unexplored. We examined the vesicular arbuscular mycorrhizal colonization in L. maackii roots compared to a random sample of native control roots. Contrary to a reduction in mycorrhizae, the total mycorrhizal colonization levels in L. maackii roots were significantly higher than native roots in April and June. Additionally, arbuscular colonization, the site of nutrient exchange, was significantly higher in L. maackii across all months of the study; in April, arbuscular colonization was 4.1 times greater in L. maackii roots than control roots. Arbuscular colonization levels also peaked earlier in L. maackii roots than in native roots, which may be explained by L. maackii's extended leaf phenology. These findings suggest that the high arbuscular colonization in L. maackii likely provides a significant benefit of increased nutrients to this invasive shrub and perhaps a competitive advantage over native plants. Additionally, these results complicate the potential role of allelopathy as a competitive mechanism – the allelochemicals must negatively affect the surrounding native plants, without disrupting the mycorrhizal network that these native plants and L. maackii depend on. The high arbuscular colonization of L. maackii is ecologically significant and likely an important mechanism enabl (open full item for complete abstract)

Committee: Carl Friese (Advisor); Mark Nielsen (Committee Member); Donald Geiger (Committee Member) Subjects: Biology; Ecology; Environmental Science; Plant Biology

Master of Science (MS), Wright State University, 2012, Biological Sciences

Garlic mustard (Alliaria petiolata) has been previously found to be significantly affected negatively by powdery mildew (Erysiphe cruciferarum). While we could not significantly corroborate those findings we did find evidence that E. cruciferarum does inhibit A. petiolata's allelopathic and competitive effects which benefits some target neighbor species such as Impatiens capensis and Elymus canadensis. We also found that the inhibition of A. petiolata by E. cruciferarum had negative consequences on another neighboring invasive species (Lonicera maackii) compared to those grown next to uninfected A. petiolata. Acer saccharum, a slow-growing species had no effect between neighbors. Sterilization treatments had variable effects on target plants, many of which mirror the effects which allelopathic plants (A. petiolata) that disrupt soil microbes seem to have. Sterilization inhibited growth of E. canadensis through the destruction of beneficial effects from microbes, while increasing the growth of L. maackii by inhibiting the pathogenic effects of microbes.

Committee: Don Cipollini Ph.D. (Advisor); James Amon Ph.D. (Committee Member); Thomas Rooney Ph.D. (Committee Member) Subjects: Biology; Botany; Conservation; Ecology; Environmental Management; Forestry; Plant Biology; Plant Pathology; Plant Propagation; Plant Sciences; Wildlife Conservation