Master of Science, The Ohio State University, 1977, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1973, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2008, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 2006, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, Miami University, 2021, Ecology, Evolution and Environmental Biology

Invasive insects and shrubs are major threats to North American forests. Emerald ash borer (Agrilus planipennis) (EAB) kills ash trees (Fraxinus spp.) resulting in canopy gaps altering resource availability. Invasive shrubs likely benefit from EAB and suppress tree seedlings. I investigated the response of woody plants to EAB-caused ash mortality in each forest strata at 24 sites throughout western and central Ohio, with particular focus on the seedling layer and introduced shrubs. In 16 sites, I explored the effects of EAB-caused canopy gaps on the invasive shrub Amur honeysuckle (Lonicera maackii) and the effects of L. maackii on woody seedlings. I found a positive relationship between ash decline and L. maackii basal area (BA) growth. Lower seedling richness corresponded with greater L. maackii BA and better ash condition. Greater L. maackii BA was associated with lower seedling abundance and recruitment. In all 24 sites, I tested two mechanisms for ecological response to EAB-caused ash mortality a: (1) EAB-caused ash decline releases growth of upper forest layers (non-ash canopy and subcanopy trees), suppressing lower strata; (2) EAB-caused ash decline increases canopy openness, releasing lower strata (shrub and seedling layer). I found evidence to support both mechanisms. Greater relative growth rates of canopy maple (Acer spp.) occurred in sites with more poor condition ash. More introduced seedlings were present in sites with more ash mortality and shrub cover. I tested the relative importance, additive, and interactive effects of EAB, non-native shrubs, and white-tailed deer (Odocoileus virginianus) on woody seedlings in the context of two environmental factors, canopy tree BA and site wetness. Results indicated a negative effect in drier forests of non-native shrubs on native seedling abundance, richness, and diversity. Deer herbivory reduced seedling diversity, especially in wetter forests. Canopy BA had a positive effect on seedling diversity (open full item for complete abstract)

Committee: David Gorchov (Advisor); Thomas Crist (Committee Member); Hank Stevens (Committee Member); Nik Money (Committee Member); Kathleen Knight (Committee Member); Amélie Davis (Other) Subjects: Biology; Botany; Ecology; Forestry

Doctor of Philosophy, The Ohio State University, 1985, Graduate School

Committee: Not Provided (Other) Subjects: Engineering

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

Master of Science (MS), Wright State University, 2007, Biological Sciences

Baumer, Marilyn Cabrini. M.S., Department of Biological Sciences, Wright State University, 2007. Tree Seedling Establishment Under the Native Shrub, Asimina Triloba. Species that form forest understory layers affect canopy tree seedling establishment worldwide. In the Eastern United States, shrub understories like Rhododendrom maximum, a native evergreen species, and Lonicera maackii, an exotic, invasive species, diminish tree seedling survival. I compared the density and survival of canopy tree seedlings under and outside patches of the native shrub, Asimina triloba (L.) Dunal (Annonaceae) (pawpaw). I also conducted a manipulative experiment to determine whether above ground or below ground competition was more important in seedling growth and survival. Above ground competition was manipulated by tying back the leaves of the pawpaw and below ground competition was manipulated by trenching the perimeter of the study plots. Tree seedling density was approximately three times greater outside pawpaw patches than under pawpaw over the range of sites. Seedlings under pawpaw were both younger and shorter than those outside of pawpaw. Survival varied by species. Acer saccharum seedlings were about one and a half times more likely to survive outside pawpaw than under pawpaw. Prunus serotina seedlings were about three times more likely to survive outside pawpaw than under pawpaw. In contrast, pawpaw did not affect the survival of Fraxinus spp. seedlings. Differing survival rates may reflect characteristics related to the species shade tolerance. Light (measured by canopy densiometer) was greater outside pawpaw than under pawpaw. No significant differences in moisture levels were detected; however, at three of the four sites, moisture was greater under pawpaw than outside of pawpaw. The combination of above ground and below ground factors was more important in the survival and growth (measured by biomass) of planted A. saccharum seedlings under pawpaw than either above ground (open full item for complete abstract)

Committee: James Runkle (Advisor) Subjects: Biology, Ecology

Master of Science, The Ohio State University, 1986, Zoology

Not available.

Committee: Theodore Bookhout (Advisor) Subjects:

Doctor of Philosophy, The Ohio State University, 2004, Evolution, Ecology, and Organismal Biology

The study was conducted at four sites in the unglaciated Allegheny Plateau region of southeastern Ohio, each was comprised of an unburned treatment unit, a periodic burn unit (prescribed fires in 1996 & 1999) and an annual burn unit (prescribed fires 1996-1999). The study sites were stratified by an integrated soil moisture index (IMI). Prior to fire treatments (1995), variation in understory species composition was most strongly correlated with topographic variations in predicted soil moisture (IMI), N mineralization rate, nitrification rate, and soil pH. Species richness was positively correlated with N mineralization rate and nitrification rate. Understory vegetation responded similarly on both the periodic and annual burn treatments, among the four study sites, and across the three IMI classes (xeric, intermediate, mesic). Post-burn compositional shifts resulted primarily from shade-intolerant species and summergreen herbs that increased in frequency from seed bank germination and also from tree seedlings that decreased in frequency. Species richness and evenness became significantly greater on burned plots as forb and graminoid richness increased. Prescribed fires also had moderate effects on tree seedling populations. Frequencies of several shade-tolerant species were significantly lower on burned sites. The frequencies of oaks (Quercus) and hickories (Carya) were not affected significantly. In 2002, there was no significant difference in the abundance of shade-tolerant seedlings among the fire treatments. Oak+hickory seedling abundance was highly variable with a small subset burned xeric plots supporting high densities (>1500/ha) of large seedlings. The rare woodland grass Calamagrostis porteri subsp. insperata was also monitored on burned and unburned sites. On annual burn patches, tiller density increased significantly relative to unburned and periodically burned patches, and annual burn patches also exhibited a sharp increase in flowering. Overall, this st (open full item for complete abstract)

Committee: Ralph Boerner (Advisor) Subjects:

Master of Science (MS), Ohio University, 2004, Environmental Studies (Arts and Sciences)

The American chestnut (Castanea dentata (Marsh.) Borkh.) was once an important tree species in the eastern United States. Following the devastating effect of the chestnut blight in the early 1900s, this species has been virtually extirpated from the overstory of the eastern deciduous forest. To facilitate the return of this species to its natural place in the overstory, The American Chestnut Foundation will soon release seeds that contain genetic material responsible for blight resistance, but preserve the genetic heritage of the American chestnut. However, the necessary requirements for site selection, site preparation, and competition control are not well understood for this species and will be essential if restoration efforts are to be successful. The goal of this study was to address these concerns and examine the effects of survival and growth of chestnut within a diverse forest management regime. Seedlings were experimentally grown in three mixed oak forests subjected to thinning, burning, a thin+burn treatment and an untreated control. Overall plant biomass between years 2002 and 2003 differed significantly among treatments for all aspects of plant growth in the thin and thin+burn treatments. As expected, there was a significant increase in light availability in the thinned treatments, and this produced a noticeable effect on seedling growth rates. A more detailed multiple regression analysis revealed a significant relationship (P ≤ 0.05) in 2002 and 2003 between light and most biomass parameters. Soil magnesium, nitrate, potassium, and sand were also significantly correlated (P ≤ 0.05) to chestnut biomass. Thus, site fertility should also be considered in reintroduction efforts. While site quality may influence growth, light conditions seem overwhelmingly important. Therefore, we recommend that American chestnut seeds be planted in areas with moderate to high light conditions (recently disturbed), with low surrounding competing vegetation (possibly after a b (open full item for complete abstract)

Committee: Brian McCarthy (Advisor) Subjects:

Master of Science, Miami University, 2005, Botany

Castanea dentata once dominated the eastern deciduous forest, but was virtually eliminated by the exotic fungus, Cryphonectria parasitica. We compared C. dentata's morphological and leaf chemistry traits to those of formerly co-occurring species. Seedlings of C. dentata, Q. rubra and L. tulipifera were grown in varying light and nitrogen regimes. After four months of growth, we measured specific leaf area, biomass, plant height and leaf nutrient content of each seedling. Castanea dentata attained greater height, biomass and leaves per plant than the other two species in most light treatments (P < .001). Results also revealed several other traits and tradeoffs of the three species. Castanea dentata's ability to accumulate greater biomass and height at the seedling stage of development may explain a great deal about its former dominance. Results also suggest that C. dentata will be able to thrive in a wide variety of intact forests when reintroduction experiments begin.

Committee: M. Henry Stevens (Advisor) Subjects: Biology, Botany