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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Temporal Variations in Spring Water Chemistry and Comparison of Variable Paleozoic Aquifer Discharges in the Ridge and Valley Province of Northwestern Georgia

Costello, Oliver Wood 21 April 2009 (has links)
The fluctuations in solute concentrations from eight springs in the Ridge and Valley Province in northwestern Georgia were used to determine flow types and to measure each aquifer’s ability to remove contamination. The target springs are located along a northeast trending line in the Ridge and Valley Province of northwest Georgia. This study determined and interpreted the fluctuations in chemistry of each of the sampled spring’s water based upon temporal variations of precipitation in the area and variations in the chemistries measured at each weekly sampling event. Analysis determined that carbonate springs that showed characteristics of diffuse flow, including stable conductance during variable rain events and greater than zero saturation indices increase the potential for the aquifer to filter potential contaminants before the spring discharge. This study attempts to show that by identifying pre-filtered drinking water sources quickly is possible, through field and laboratory analysis.
2

Vascular Flora and Biogeographic Affinity of the Sevier Shale Knobs of Northeastern Tennessee

Levy, Foster 01 May 2021 (has links)
In the Ridge and Valley physiographic province, knobs stand out as anomalous landforms embedded within a region of long, parallel ridges and valleys. In northeastern Tennessee, knobs are associated with the Sevier shale. Well-drained, acidic, channery loam Montevallo soils cover uplands of these knobs. A flora of the Sevier shale knobs of northeastern Tennessee identified 265 taxa in 57 plant families of which 13.6% were exotic and three were state listed (Berberis canadensis, Ruellia purshiana, Silene caroliniana var. pensylvanica). Many taxa had rarely or never been collected in northeastern Tennessee. The flora of the Sevier shale knobs was most similar to dolomite and limestone barrens of southwestern Virginia but among the species rarely collected in northeastern Tennessee, the greatest number was shared with floras of the Sequatchie Valley, middle Tennessee cedar glades, and barrens of the Tennessee eastern Highland Rim.
3

Effects of Clearcutting with Whole Tree Harvesting on Woody and Herbaceous Plant Diversity After 17-Years of Regrowth in a Southern Appalachian Forest

Wright, David Kenyon 28 April 1998 (has links)
This study examines the effects of clearcut regeneration with whole-tree harvesting on plant diversity. Three approaches were used to study changes in species composition and structure: (1) forest level, (2) stand level, and (3) diversity indices. Within each approach the forest was stratified into three horizontal vegetative regions based upon height: herb (< 1 m), shrub (between 1 and 5 m), and tree (> 5 m). Between the pre-harvest and 17-year-old forest, the relative percent cover of 3 out of 45 herbaceous and 2 out of 34 woody species were found to be significantly different (df = 3; a = 0.10) in the herb stratum; the importance value (average of relative basal area and stem density) of 2 out of 25 woody species in the shrub stratum; and 1 out of 21 woody species in the tree stratum. Within stands, the three lower quality, 17-year-old stands (SI50 = 12.2, 15.2, and 18.3 m) most resembled their pre-harvest composition; however, increases in ericaceous species were observed in the herb and shrub strata potentially inhibit the future regeneration of tree species. The SI50 = 21.3 m stand incurred the greatest changes in composition potentially due to the lack of fire as a disturbance mechanism. The major mechanism that has caused the shifts in species composition and structure is the change in the microenvironment due to the removal of the overstory, which has shifted the competitive advantages from one species to another. In all cases, diversity indices were not found to be significantly different between the 17-year-old and pre-harvest forests. Diversity indices were therefore determined to have limited use if a manager wants to know specific compositions and/or abundance of species. / Master of Science
4

Vernal Pool Mapping and Geomorphology in the Appalachian Mountains of Pennsylvania

Blackman, Taylor Nathaniel 11 June 2019 (has links)
Vernal pools are small seasonally-ponded wetlands that provide crucial habitat for amphibian reproduction and support trophic levels beyond their boundaries. The Ridge and Valley physiographic province in Pennsylvania is known to have vernal pools, but a regional inventory and geomorphology assessment is needed. My research is split into two independent parts focusing on the higher elevation areas of this region to determine vernal pool distribution and characteristics. Vernal pools were mapped using a LiDAR based suitability model and leaf-off aerial imagery interpretation. Four terrain rasters derived from a 1-meter DEM (modified wind modified wind exposure, terrain surface convexity, topographic position index, and a multiresolution index of valley bottom flatness) were used in the suitability model. An analysis of variance (ANOVA) and Tukey's HSD test found a significant difference using the model between terrestrial (non-wetland) habitat and vernal pools. Photo interpretation and field surveying lead to an inventory of 1011 vernal pools. Geomorphology was assessed from 13 variables to determine the best for vernal pool prediction. Three variables were significant for the occurrence and frequency of vernal pools; saddles with higher surface area, 0.6 to 1.5 kilometers between the summits of parallel ridgelines, and the presence of periglacial related solifluction. Vernal pool distribution is greater than previously known and they occur in predictable settings. Further research should focus on how and where vernal pools form, their impact on water quality, role in forest ecology, and ways to legally protect them at the state level. / Master of Science / Vernal pools are seasonally-ponded wetlands that are very important for amphibian reproduction. The Appalachian Mountains of Pennsylvania are known to have vernal pools, but comprehensive inventory is lacking. My research consists of two parts that focus on the higher elevation areas and assess the distribution and qualities of the vernal pools. Vernal pools were mapped using a LiDAR based suitability model and leaf-off aerial imagery interpretation. Statistical analysis was completed to prove that there was a significant difference in terrain morphology between non-wetland habitat and vernal pools. This research resulted in a total inventory of 1011 vernal pools. Results found that vernal pools were likely occur in landscape positions with higher surface area, 0.6 to 1.5 kilometers between the summits of parallel ridgelines, and the presence of topographic features indicative of glacial processes. Vernal pools are much more abundant than previously known and they occur in predictable settings. Further research could focus on the formation of vernal pools, impact on water quality, role in forest ecology, and ways to legally protect them at the state level.

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