Thesis (Ph. D.)--Lehigh University, 1997. / Includes vita. Bibliography: leaves 163-175.

Fire suppression in the southern and central Appalachian Mountains has resulted in an alteration to vegetation structure and composition. For this research the dominant species, abundance, density and age structure of the ericaceous shrub layer is characterized on four sites across the southern and central Appalachian Mountains. Fire histories for each of the sites varied, and were determined in previous research using dendroecological techniques. Over 800 ericaceous shrubs were collected, species included Pieris floribunda (Pursh) Bentham & Hooker f., Rhododendron maximum L. and Kalmia latifolia L.. Basal area of ericaceous shrubs was significantly different between sites. Age structures show that when fire suppression started Ericaceae began to establish. A few Ericaceae cross-sections displayed scars, that are likely associated with fire events, suggesting they probably survived mild fire events. Ericaceous shrub age structures were also compared to SPB outbreaks and PDSI. There were no significant correlations, but field observations suggest that SPB may be providing conditions suitable for Ericaceae establishment. Topographic patterns reveal that Kalmia latifolia is most abundant at mid-slope positions and decreases at higher and lower slope positions. There were significant differences in the density between slope positions averaged across all sites. Sites with the most recent and frequent fires did not have any of the three ericaceous shrubs collected at the slope bottom or ridge-top. At the most fire-suppressed site Ericaceae are present at every slope position. Age structures reveal that the oldest Ericaceae are found at the mid-slope positions while the age of thickets appears to decrease away from the mid-slope position. This pattern suggests that Ericaceae are moving into slope positions where they were previously less abundant. Sites with the most recent frequent fire regime seem to have prevented Ericaceae from heavily inhabiting high and low topographic positions while also reducing the overall basal area and density of Ericaceae.

That tornadoes cannot occur in mountains due to disruptive influences of the complex terrain is a common misperception. Multiple tornadoes occur each year in mountainous environments, including the Appalachian Mountains. Copious research examines the influences of complex terrain on large severe weather systems such as multicell convective systems and squall lines, but research is lacking investigating this same relationship for smaller-scale severe weather phenomena like supercells and tornadoes. This study examines how complex terrain may have influenced the rotational low-level wind fields of fourteen supercell thunderstorms in the Appalachians. The terrain variables include elevation, land cover, slope, and aspect. Using GIS mapping techniques, the individual storm tracks were overlaid onto elevation, land cover, slope, and aspect layers; points along the storm tracks were measured to correlate storm intensities with the underlying terrain. Hypotheses predict that lower elevations, areas of shallower slopes, agricultural land covers, and terrain features with a southeasterly orientation represent terrain variables that would enhance low-level rotation in the lower levels. Results indicate that elevation has a significant impact on storm rotational intensity, especially in mountainous regions. Lower and flatter elevations augment storm rotational intensity, and higher elevations decrease storm rotational intensity. Additionally, northern and western facing slopes exhibited a negative relationship to storm intensity. A qualitative examination revealed vorticity stretching to be evident in eight of the fourteen storms; with vorticity stretching evident on both southeasterly and northwesterly slopes. Future research on appropriate scale for storm-terrain interactions could reveal even stronger relationships between topography and supercell thunderstorms. / Master of Science

I examined streams in the Joyce Kilmer-Slickrock wilderness to determine if streams responded to logging following 75 y of recovery. Joyce Kilmer was never logged and the Slickrock wilderness was logged from 1917 until 1922. Wood was common in unlogged streams and averaged 417 m³ of wood/ha of streambed. Logged streams had significantly less wood (1.1 m³ of wood/ha of stream), probably because of the construction of railroads in streambeds used to remove timber. Fine substrates (<5.6 mm diameter) were less abundant in logged streams and the retention of fines decreased as wood volume decreased. Species diversity was similar between streams in unlogged and logged catchments; however, the abundance of several taxa and functional feeding groups did differ. Streams in unlogged catchments had significantly greater proportions of shredders while streams in logged catchments had significantly greater proportions of scrapers. Ecosystem parameters showed that the linkages between streams and the forests they drain were weaker in logged than unlogged streams and that unlogged streams derived a greater proportion of fixed carbon from riparian vegetation. Stream-forest linkage strength increased as debris dam abundance increased, while the use of riparian vegetation inputs increased as moss increased. Contrary to predictions, solute storage was significantly greatest in logged catchments and negatively related to debris dam abundance that decreased streambed permeability. Additionally, phosphorus retention, instead of being enhanced by solute storage, was negatively related to transient storage. Uptake velocity was significantly greater in unlogged than logged streams and significantly related to debris dam abundance. Mean breakdown rate of experimental leaf packs and wood veneers was not significantly different between unlogged and logged streams. Leaf breakdown was strongly related to shredder colonization, while wood breakdown was unrelated to variables measured. Much of the persisting disturbance to streams by past logging was directly or indirectly related to differences in wood volume, debris dam frequency, and streambed substrate composition. Results support the hypothesis that logging results in a downstream shift from the headwaters in ecosystem function and that logging disturbance to streams likely persists for centuries. / Ph. D.

This study examines the spatial distribution of surface charcoal after a managed fire and its relationship to fire intensity and site characteristics. Such studies are lacking for the southern Appalachian Mountains. In April 2010, The Nature Conservancy conducted a ~150ha prescribed burn in pine- and oak-dominated forests on the eastern slope of Middle Mountain in western Virginia. Data were from three randomly located transects totaling 2751m from the base of the slope extending to the highest elevations. At 50m intervals I collected 400cm° surface samples (n=56) down to mineral soil, and recorded the nearest four trees, their diameters and bole char height, and other site and understory characteristics. Charcoal fragments >2mm were wet-sieved from 200mL subsamples of the surface material, dried, and weighed. Charcoal deposition and char heights on trees examined in this study showed high spatial variability in fire intensity. Average charcoal deposition across all samples was 103 kg/ha, with individual samples ranging from 0-884kg/ha, which was in the range of findings from other studies. Char height was weakly correlated with charcoal abundance suggesting a relationship between fire intensity and charcoal production. Slope was moderately correlated with charcoal deposition, with higher deposition on steeper slopes. Average char height for all trees and species was in the range of 1-3m, but char height on pines averaged 7.3m, where fires intensity appeared to increase. This work can inform land managers on fire behavior and carbon flux and has implications for reconstructions of long-term fire history from soil charcoal. / Master of Science

This research aims to analyze the spatial and temporal characteristics of instrument meteorological conditions (IMC) over the Southern Appalachian Region from 2008 to 2023, utilizing Meteorological Terminal Aerodrome Report (METAR) stations across six USGS-defined physiographical provinces. IMC is defined as visibility less than three statute miles and/or cloud ceiling heights less than 1,000 feet above ground. Percentage of hours reporting IMC are considered on an annual, seasonal, and hourly basis. The greatest increase in IMC over the period occurs in the Piedmont province, and the greatest decrease in the Interior Low Plateaus province. All provinces experience the greatest amount of IMC in wintertime, and the season with the fewest IMC hours varies by province. All provinces see a maximum hour of IMC within three hours following sunrise except summertime in the Interior Low Plateaus, which experiences the highest frequency of IMC within two hours prior to sunset.

Many coal mines in southwestern Virginia and West Virginia are plagued with excessive deterioration of roof shales. Shale flakes and sheets spall off the roofs at unpredictable intervals and create hazards in many coal mines (P1.1). The failures are more frequent during the summer months when the incoming air is at a higher temperature than the roofs and walls of the mine. This differences in temperature causes the moisture of the air to condense on the cooler parts of the mine. Prof. C.T. Holland, Department of Mining Engineering, Virginia Polytechnic Institute, has suggested that this type of roof failure may depend upon some mineralogical or chemical change caused by the increase in moisture on the rooms of the mine. In addition to the weathering process, some roof shales are notoriously susceptible to failure in those places where ground-water seepage is prevalent. The failures caused by this type of situation at the entry of a mine are usually more predictable than those caused by weathering. The purpose of this investigation was to determine if there were any significant differences in the mineral, chemical, or textural compositions of roof rocks which have failed and those which have not. / Master of Science

We investigated the climatic sensitivity of oak species across a wide elevation range in the southern Appalachian Mountains, an area where greater knowledge of oak sensitivity is desired. We developed three tree-ring chronologies for climatic analyses from oak cores taken from the Jefferson National Forest, Virginia, and Great Smoky Mountains National Park, Tennessee. We statistically compared the three chronologies with monthly climatic data from 1930 to 2005. The results of our analyses suggest that oak species in the southern Appalachian Mountains require a cool, moist summer for above average-growth to occur. The climate signal increased in duration from high to low elevational and latitudinal gradients, indicating a strong moisture-preconditioning signal during the previous fall at our lowest elevation site. A notable finding of this research was the degree of responsiveness in oaks that are growing in forest interior locations where strong climate sensitivity would not be expected because of the effects of internal stand dynamics. Furthermore, the relationships between evapotranspiration rates and the geographic factors of elevation, latitude, and aspect influence the climate signals at the three sites. Our research suggests that oaks located in a warm and xeric climate experience more physiological stress and put forth a more varied climatic response.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Six maps included in back pocket. Vita. Abstract. Includes bibliographical references (leaves 115-116). Also available via the Internet.

Thesis (Ph. D.)--Carleton University, 1993. / Also available in electronic format on the Internet.