Master of Science (MS), Ohio University, 2013, Plant Biology (Arts and Sciences)

Reintroduction of blight-resistant chestnuts is on the horizon, but appropriate reintroduction sites need to be identified and field-tested. Concurrently, there is an increasing effort to restore reclaimed surface mined lands in the Appalachian Region to hardwood forest. American chestnut is a hardwood species of interest for these restoration projects as Appalachian mine lands could serve as reintroduction sites for blight-resistant chestnuts. The goal of this study was two-fold: 1) Field-test the similarity (in terms of growth, survival, and leaf properties) of blight-resistant hybrids to American chestnut. 2) Assess the growth, survival, and leaf properties of hybrid chestnuts on reclaimed mine lands across a wide geographic range, and examine mine land conditions (soil properties, light availability, competition with other vegetation, local climate) that may influence chestnut success. In 2008, parent species (American chestnut and Chinese chestnut), along with hybrid chestnut taxa, were planted as seeds on reclaimed mine lands in six Appalachian states. I revisited plantings in Pennsylvania, Ohio, Kentucky, and Tennessee in 2012 to reassess chestnut growth and survival, as well as examine various site conditions. Across all sites, Chinese chestnuts had greater five-year survival (62.5%) than most hybrids (41.2% - 42.7%) and American chestnuts (41.4%), but growth did not significantly differ among all chestnut taxa. Conversely, site had a strong effect on chestnut growth. On average, chestnuts grown in Kentucky and Tennessee were 72 - 124 cm taller than chestnuts grown in Pennsylvania and Ohio after five growing seasons. Decreased growth in Pennsylvania and Ohio may be related to increased competition from other plants for light and water, and lower average minimum temperature of these sites in the northern part of the American chestnut range. From my results, American chestnut reintroduction on reclaimed mined lands seems promising in some areas, but control of (open full item for complete abstract)

Committee: Brian C. McCarthy (Advisor); Jared L. DeForest (Committee Member); David M. Rosenthal (Committee Member) Subjects: Ecology; Plant Biology

MS, University of Cincinnati, 2005, Arts and Sciences : Biological Sciences

Reintroduction of chestnut-blight-resistant Castanea dentata may be facilitated by understanding genetic variation, and how its transmission is affected by a genetic bottleneck. Genetic diversity for groups of chestnuts from an isolated Wisconsin population (one group of nine founders and three groups of descendants) and two natural transects were compared. Two minisatellite DNA probes revealed 84 markers among nine founders (ca. 24 loci surveyed) that were analyzed for transmission. The descendants were more heterozygous (estimated heterozygosity = H = 0.5554) and less similar (S = 0.5329) compared to the founders (H = 0.5179; S = 0.5636; p<0.0504). Infected individuals were more heterozygous and less similar than uninfected individuals from Wisconsin (H = 0.5728 versus 0.5319; S = 0.5245 versus 0.5708, respectively; both differ at p<0.01). When compared to natural transects ( H = 0.5224, S = 0.6101), the founders showed no significant differences in heterozygosity or similarity but the descendants showed increased heterozygosity and decreased similarity (p<0.03). These results bode well for reintroduction since pronounced effects of drift and inbreeding were not detected in the West Salem population.

Committee: Dr. Steven Rogstad (Advisor) Subjects:

Master of Science (MS), Ohio University, 2012, Environmental Studies (Arts and Sciences)

Restoration of American chestnut (Castanea dentata (Marsh.) Borkh.) is currently underway in eastern North American forests. American chestnut and eastern hemlock (Tsuga canadensis (L.) Carr.) trees historically co-occurred in these forests. Today, hemlock-dominated forests are in decline due to hemlock wooly adelgid (Adelges tsugae Annand) infestation, and as such, may serve as appropriate habitat for chestnut reestablishment. To investigate this notion, I evaluated the performance of American chestnut seedlings planted under healthy eastern hemlock-dominated canopies. Two process-oriented greenhouse experiments were also performed to study the response of American chestnut to drought stress and to test the competitive performance of chestnut against red maple (Acer rubrum (L.)), the most abundant hardwood found in the understory of regional hemlock-dominated forests. After two growing seasons, mean chestnut seedling survival in the field experiment was 6.6%. Seedling survival was significantly higher among trees that lacked a protective tree tube, suggesting low light levels played a major role in seedling mortality. In the drought stress experiment, American chestnut exhibited significantly higher mortality under a severe drought treatment compared to the control group. The moderate stress treatment also responded poorly to drought; however, results did not differ significantly with the control group. In the competition experiment, American chestnut grew significantly taller than red maple. The results of this study caution against the underplanting of bare-root chestnut seedlings in low light conditions or where moisture may be limiting to establishing seedlings.

Committee: Brian McCarthy PhD (Advisor); James Dyer PhD (Advisor); Jared DeForest PhD (Committee Member) Subjects: Ecology; Environmental Science; Environmental Studies

Master of Science (MS), Ohio University, 2007, Environmental Studies (Arts and Sciences)

Forests are preferred as a post-mining land use in the eastern United States. In Ohio, early reforestation included Pinus spp. monocultures which may not conserve the flora and fauna of historic hardwood communities. American Chestnut, Castanea dentata (Marsh.) Borkh., is an historic keystone species of eastern deciduous forests. We evaluated the growth and survival of 1-year-old Castanea dentata seedlings in field and garden conditions representing mine spoil from previously strip mined lands in eastern Ohio. Pure and hybrid bareroot seedlings were grown at three selected field sites ranging in mean pH from 3.6 to 7.7. Hybrid seedlings were inoculated with the mycelium Pisolithus tinctorius (Pers.) Coker and Couch, (‘Pt'). Soil was analyzed for Al, Mn, Fe, and S, as well as base nutrients and other edaphic qualities. A garden experiment supplemented field analysis with a controlled mycorrhizae x pH x nutrient interaction. Field growth variables were measured for 2005 and 2006. Garden seedlings were harvested and biomass allocation was measured for 2006. Field parameters were significantly (P < 0.05) accelerated by Pt inoculation, except for height. Pure non-inoculated seedlings displayed tall slender stems, while hybrid inoculated seedlings showed bushier growth with greater stem diameter, and lower branching. Field sites displayed significant (P < 0.05) differences, with overall seedling performance being best on bare, un-reclaimed spoil, compared to grass or forb cover. This may be consistent, based on prior studies, with historic disturbance regimes. Growth was lowest in association with herb cover, suggesting that aggressive grasses and legumes such as those used in modern reclamation practices, may inhibit establishment of seedlings early-on. Garden controls revealed that in contrast to prior studies of container grown Fagaceae, chestnut growth was not positively influenced, and showed ca. 70% mortality from addition of controlled release fertilizer (CRF) into (open full item for complete abstract)

Committee: Brian McCarthy (Advisor) Subjects:

Doctor of Philosophy (PhD), Ohio University, 2006, Plant Biology (Arts and Sciences)

Forests are characterized by dynamism in species composition, structure and function. These dynamics, in turn, are often related to disturbance. These disturbances, therefore, are intrinsically linked to the biology of forest ecosystems. In order to understand and ultimately manage forest ecosystems, the role of disturbance in the systems must be ascertained. Disturbances that occur in forests rarely kill all of the existing trees. Therefore evidence of disturbance in the surrounding landscape is often recorded as a growth response in the surviving trees. In this dissertation I present four projects that were executed to develop an understanding of disturbance and growth dynamics in deciduous forest ecosystems of eastern North America. In each project, analysis of tree-rings (dendroecology), was used as the primary data source in the analyses. The first project focuses on the growth of American chestnut (Castanea dentata) in a Wisconsin oak forest. Castanea dentata exhibited a range of growth responses suggesting plasticity in ecological response that 1) offers promise for restoration efforts and 2) may have contributed to its dominance prior to the chestnut blight. The second dissertation project addresses anthropogenic disturbance and the formation of oak savanna in central Kentucky. Because of the > 300 year depth of the chronology in this project, I was able to develop a hypothetical model linking human population dynamics, land use eras, and ecosystem structure. The third and fourth projects work in tandem. The third project presented a vetting of the commonly employed technique of fire-history reconstruction using fire scars in oak samples. In this project we show that 1) scarring occurs from sources other than fire in the landscape, and 2) that multiple annual fires may not be recorded in the tree-ring record. Overall, the tree-ring record proved effective in fire history reconstruction. In the final project of the dissertation, I used this technique to devel (open full item for complete abstract)

Committee: Brian McCarthy (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: