No description available.

No description available.

Thickets of Rhododendron maximum (Rm) in the southern Appalachians impose severe limitations on the regeneration of hardwood and coniferous seedlings. Interactions between Rm thickets and ectomycorrhizal colonization were examined to explain seedling inhibition. Experimental blocks were established in and out of Rm thickets in a mature, mixed hardwood/conifer forest in Macon County, North Carolina. Planted seedlings of red oak (Quercus rubra) and hemlock (Tsuga canadensis) were harvested at the end of the first and second growing seasons. Litter manipulation had no effect on total mycorrhizal colonization. Mycorrhizal colonization and ramification index (# mycorrhizae cm-1) were depressed and colonization by Cenococcum geophilum increased in blocks with versus without Rm. After the first year, percent colonization of T. canadensis not in Rm thickets (62 %) was three times higher than in Rm thickets (19%), and the ramification index was increased by more than a factor of four (2.83 versus 0.61). Mycorrhizal colonization levels were correlated with root weight and shoot weight in both hemlock and oak seedlings, but did not explain most of the variation observed. Sporocarps of 69 putatively ectomycorrhizal species were collected on the blocks. Species diversity and overall community structure was similar in and out of Rm thickets. Individual species, i.e. Lactarius speciosus and Russula krombholzii, were significant indicators of forest without Rm thickets. Rhododendron maximum thickets probably affect the process of mycorrhization. The reduced level of mycorrhizal capacity under Rm thickets could be a factor in the increased seedling failure in Rm thickets. / Master of Science

Rosebay rhododendron (Rhododendron maximum L.) is an evergreen ericaceous shrub that plays a dynamic role in the southern Appalachian forests. Commonly located on mesic sites, this understory shrub forms dense thickets that greatly reduce the amount of light available to herbaceous and woody plants found on the forest floor. Past research has shown that silvicultural methods can be used to eradicate R. maximum, however it is unclear which of these methods is most efficient and what effects other than stem mortality may occur. In this study, treatments involving prescribed fire, mechanical cutting, and herbicide applications were applied to R. maximum dominated forests in southwestern Virginia to determine what effect seven different silvicultural treatments had on 1) controlling of R. maximum as a forest weed 2) fuel loading inside of a R. maximum thicket, and 3) canopy tree seedling regeneration. Mechanical cutting treatments were successful in reducing R. maximum basal area per acre; however stump sprouting and increased fuel loading occurred. Herbicide applications were successful in controlling only the smallest diameter class of R. maximum stems. Prescribed fire reduced litter layers and caused delayed mortality on R. maximum stems three years following treatment. Hemispherical photographs taken within each plot showed that silvicultural treatments that successfully increased the amount of light entering each plot were influential in seedling establishment three years following treatments. Results from this study can be used to further perfect silvicultural applications that alleviate R. maximum cover on the forest landscape. / Master of Science

No description available.

Historically, the Kentucky Inner Bluegrass blue ash-oak savanna-woodland was the primary ecosystem of the Inner Bluegrass Region (IBR) of Kentucky. After European settlement, the majority (>99%) of Bluegrass savanna was converted to agricultural and urban land uses. Currently remnant savanna tree species are failing to recruit. Therefore, a long-term restoration ecology project researching competition and disturbance on seedling establishment, survival, and growth has been established at Griffith Woods (the largest remaining savanna in Kentucky) in Harrison Co., KY. Fourteen native hardwood tree species (a total of 6,168 seedlings) have been experimentally planted. Light, soil, surrounding vegetation, and herbivory, factors thought to influence seedling survival, have been initially assessed. Results show that soils differed spatially in P, Ca, Mg, Zn, pH, N percent and soil organic matter percent. Light was significantly reduced by diffusive filtering through vegetation. Vegetation biomass was influenced by pH and Mg. Initial seedling survival was high, but significantly differed by species type, location, and soil pH, Mg, and Zn. This research demonstrates that under a similar range of conditions, native hardwood tree seedling establishment is possible. Therefore, the potential exists to restore Bluegrass savanna-woodland in order to return proper ecological functioning into a degraded landscape.