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.

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.

Ecologists continue to debate the role of fire in forests of the southern Appalachian Mountains. How does climate influence fire in these humid, temperate forests? Did fire regimes change during the transition from Native American settlement to Euro-American settlement? Are fire regime changes resulting in broad vegetation changes in the forests of eastern North America? I used several approaches to address these questions. First, I used digitized fire perimeter maps from Great Smoky Mountains National Park and Shenandoah National Park for 1930-2009 to characterize spatial and temporal patterns of wildfire by aspect, elevation, and landform. Results demonstrate that fuel moisture is a primary control, with fire occurring most frequently during dry years, in dry regions, and at dry topographic positions. Climate also modifies topographic control, with weaker topographic patterns under drier conditions. Second, I used dendroecological methods to reconstruct historical fire frequency in yellow pine (Pinus, subgenus Diploxylon Koehne) stands at three field sites in the southern Appalachian Mountains. The fire history reconstructions extend from 1700 to 2009, with composite fire return intervals ranging from 2-4 years prior to the fire protection period. The two longest reconstructions record frequent fire during periods of Native American land use. Except for the recent fire protection period, temporal changes in land use did not have a significant impact on fire frequency and there was little discernible influence of climate on past fire occurrence. Third, I sampled vegetation composition in four different stand types along a topographic moisture gradient, including mesic cove, sub-mesic white pine (Pinus strobus L.) hardwood, sub-xeric oak (Quercus L.), and xeric pine forests in an unlogged watershed with a reconstructed fire history. Stand age structures demonstrate changes in establishment following fire exclusion in xeric pine stands, sub-xeric oak stands, and sub-mesic white pine-hardwood stands. Fire-tolerant yellow pines and oaks are being replaced by shade-tolerant, fire sensitive species such as red maple (Acer rubrum L.) and hemlock (Tsuga canadensis L. Carr.). Classification analysis and ordination of species composition in different age classes suggest a trend of successional convergence in the absence of fire with a shift from four to two forest communities.

This thesis is a case study aimed at a key argument in the emerging field of Civil War medical and environmental history. While historians have long acknowledged disease as a major killer during the Civil War, only recently have environmental and medical historians turned their collective attentions to unpacking the complex interconnections of disease, environmental conditions, and culture. By examining the 58th North Carolina Infantry Regiment from the mountains of western North Carolina, this thesis asserts that the combined role of the disease environment and conditions in military camps created the massive outbreaks of disease that characterized the seasoning process of the regiment. Furthermore, the soldiers were practical in their response to conditions, weighing family, nation, and other factors in the face of death. When the threat of disease combined with personal and other factors, many soldiers deserted or took other actions of self-preservation over loyalty to the Confederacy.