Southern Blue Ridge Research Articles

Temporal and Spatial Variations in Microplastic Concentrations in Small Headwater Basins in the Southern Blue Ridge Mountains, North Carolina, USA

Microplastics (MPs) are ubiquitous contaminants of emerging concern that require additional study in freshwater streams. We examined the spatial-temporal variations in MP concentrations and characteristics within two headwater basins in the Southern Appalachian Mountains of western North Carolina over ~1 year. Atmospheric samples were also collected to determine the significance of atmospheric MP deposition to these relatively small streams. MP concentrations in both basins were within the upper quartile of those reported globally, reaching maximum values of 65.1 MPs/L. Approximately 90% of MPs were fibers. MP composition was dominated by polystyrene, polyamides, and polyethylene terephthalate. Spatially, concentrations were highly variable and increased with development, indicating anthropogenic inputs from urbanized areas. MP concentrations were also elevated in forested tributary subbasins with limited anthropogenic activity, suggesting atmospheric deposition was an important MPs source. Significant atmospheric inputs are supported by high atmospheric depositional rates (ranging between 7.6 and 449.8 MPs/m2/day across our study sites) and similarities in morphology, color, and composition between atmospheric and water samples. Temporally, MP concentrations during storm events increased, decreased, or remained the same in comparison to base flows, depending on the site. The observed spatial and temporal variations in concentrations appear to be related to the complex interplay between precipitation and runoff intensities, channel transport characteristics, and MP source locations and contributions.

Drainage area is not enough: multivariate hydraulic geometry in the Southern Blue Ridge Mountains, U.S.A.

ABSTRACT Regional hydraulic geometry curves, which relate drainage area to channel morphology, are powerful tools for river restoration and watershed management. While there is a strong correlation between channel morphology and drainage area, the importance of watershed slope and relief on channel-forming flow, especially in mountainous regions, cannot be ignored. This research used single variable power functions along with multiple regression to determine which network- and or local-scale variables are influencing channel morphology in the Southern Blue Ridge Mountains. Within this region, watershed topography (i.e. relief and slope) and or local-scale characteristics (e.g. channel slope and sinuosity) are better predictors of channel morphology than drainage area. Additionally, the importance of local-scale characteristics in the multiple regression models provide strong evidence that site-specific conditions can be just as important as watershed characteristics in determining channel morphology. While multiple regression has been used to create hydraulic geometry equations in other regions, this is the first study that determined whether non-drainage area multiple regression models perform better than models that include drainage area. With the increasing ease with which network- and local-scale characteristics can be calculated, this research shows a clear need to incorporate additional network- and or site-specific characteristics into hydraulic geometry equations.

Mowers versus growers: Riparian buffer management in the Southern Blue Ridge Mountains, USA

AbstractDespite long‐standing knowledge of the benefits of riparian buffers for mitigating nonpoint source pollution, many streams are unprotected by buffers. Even landowners who understand ecological values of buffers mow riparian vegetation to the streambank. Do trends in rural riparian conditions reflect the development of riparian forest science? What motivates residential riparian management actions? Using high‐resolution orthoimagery, we quantified riparian conditions and trends between 1998 and 2015 in the rural upper Little Tennessee River basin in Macon County, North Carolina and explored how landowners view riparian zone management and riparian restoration programs. Buffer composition in 2015 was as follows: no buffer (32.5%), narrow (19.3%), forested (26.7%), shrub (7.2%), and intermediate (7.0%). Relative to 1998, the greatest decrease occurred in the no buffer class (−17.7%, 46 km) and the largest increases occurred in the shrub (+72.5%, 20 km) and narrow (12.6%, 14 km) classes. Forested buffer marginally increased. Semi‐structured interview data suggest that landowners prioritize recreational and scenic aspects of riparian buffers over ecological functions such as filtration and bank stabilization. Riparian restoration programs might be made more enticing to non‐adopters if outreach language appealed to landowner priorities, design elements demonstrated intentional management, and program managers highlighted areas where ecological goals and landowner values align.

Systematics of the Ocoee Salamander (Plethodontidae: Desmognathus ocoee), with description of two new species from the southern Blue Ridge Mountains.

The "mountain" dusky is a charismatic ecomorph of Dusky Salamander (Desmognathus): smaller (~20-50mm SVL), more terrestrial and montane woodland species, typically with round tails and extremely variable, often colorful patterns. Originally considered a single species (D. ochrophaeus), populations across the Appalachians are now divided into D. abditus, D. carolinensis, D. ochrophaeus, D. ocoee, and D. orestes, which do not form a clade but are instead scattered across the phylogeny of Desmognathus. A Coastal Plain species with a mountain dusky phenotype (D. apalachicolae) is also nested within a lineage related to D. ocoee. Within the current concept of D. ocoee, there are up to 8 genetically distinct geographic lineages which display significantly different but substantially overlapping morphologies. Recent studies have suggested that as many as six species could reasonably be delimited based on genetic data. We evaluate the strength of that evidence here and find support for five species in the D. apalachicolae + D. ocoee group. The first is D. apalachicolae in essentially its originally described form from the Coastal Plain. The second and third are D. adatsihi sp. nov. and D. balsameus sp. nov., endemic to the Great Smoky/Plott Balsam and Great Balsam Mountains, respectively. The fourth corresponds to the resurrected D. perlapsus for populations from the Alarka and Cowee Mountains in North Carolina, through the Chattahoochee River drainage to the Fall Line in the Piedmont of Georgia and Alabama. The fifth is D. ocoee, here restricted to populations in the Nantahala and Unicoi Mountains and southernmost Blue Ridge escarpment, along with previously recognized populations from the Cumberland Escarpment and Cumberland Plateau of south-central Tennessee and northeastern Alabama. This taxon concept of D. ocoee includes three deeply divergent geographic genetic segments that hybridize across two contact zones, while D. apalachicolae may be nested within some southern Blue Ridge populations of D. ocoee. The resurrected form of D. perlapsus also exhibits some admixture with the newly restricted D. ocoee. While this taxonomic arrangement is robust and stably derived from mitochondrial, morphological, and nuclear data, more sophisticated future analyses sampling additional populations and loci to estimate relationships may reach more subtle conclusions regarding the identity of some lineages within D. ocoee.

The Harvest Operability Index (HOI): A Decision Support Tool for Mechanized Timber Harvesting in Mountainous Terrain

Forest operations have become increasingly reliant on mechanized harvesting equipment due to their increased production capacities in competitive markets. However, operating heavy machinery in mountainous terrain poses numerous operational and accessibility challenges from steep slopes, erosion risk, and poor road access. Geographic Information Systems (GIS) have effectively been used in various studies to identify areas in mountainous landscapes that pose no or reduced constraints for harvesting equipment operation. This study introduces the Harvest Operability Index (HOI), which rates a landscape for wheel-based equipment suitability (i.e., operability) and assesses its application in 13,118 ha of the Jocassee Gorges Natural Resource Area, situated on the Southern Blue Ridge Escarpment in Northwestern South Carolina, USA. The HOI incorporated slope, distance from roads, cost distance from major highways, primary Streamside Management Zones (SMZ), stand age, and soil suitability ratings for harvesting equipment operation. Upon reclassification to a 5-tier suitability scale, the HOI revealed 60% (7824 ha) of the case study area was in a Slope Exclusion Zone, or land area inoperable for wheel-based equipment due to steep slopes. Values of Very Poor and Poor Operability occupied less than 1% (213 ha) of land area whereas Moderate Operability values were 9% of the land area (1257 ha). Values of Good Operability occupied 18% (2442 ha) of the study area and values of Very Good Operability occupied 10% (1381 ha). These results reflected the challenges of mechanized harvesting in the study area due to a preponderance of steep slopes and poorly suited soil. Our model delineated areas of high equipment operability in two locations in the study area, despite a lack of recent logging activity around them. Results of the HOI analysis offer an accessible way for forest managers to better prioritize logging operations in areas that are highly operable and therefore more likely to possess lower overall harvesting costs, for wheel-based harvesting systems. The HOI can also be used as an asset for other forest management priorities, such as identifying highly operable areas that can use timber harvesting for fuel reduction and ecological restoration in fire-dependent forests. This model can be applied to various other regions where mountainous terrain poses a limitation to wheel-based harvesting equipment operation- and where wheel-based equipment is essential to advance the pace and scale of harvesting for ecological restoration.

Timing of Grenville magmatism in the southern Blue Ridge, North Carolina, USA: New in situ zircon U-Pb geochronology and implications for timing of Rodinian orogenesis in eastern Laurentia

Mesoproterozoic metaplutonic rocks from the southern French Broad massif in southwestern North Carolina preserve Grenville magmatic and metamorphic ages (1.28–1.0 Ga). New in-situ zircon U-Pb measurements from eight basement lithologies, obtained by laser ablation and ion-probe techniques, delineate Elzevirian (1283–1250 Ma), Shawinigan (1191–1126 Ma), and Ottawan (1034–1008 Ma) magmatism and metamorphism. Magmatism produced dominantly calc-alkaline plutons with normative compositions of quartz diorite, quartz monzodiorite, granodiorite, and monzogranite. The majority of magmatism in the field area occurred between ca. 1190 and 1125 Ma, a period correlative to the Shawinigan phase of the Grenville orogeny. Syn- to post-emplacement metamorphism of these units is evidenced by complex zircon U-Pb systematics in all Shawinigan age plutons. Ottawan magmatism, expressed by emplacement of the Max Patch granite and protoliths of the Earlies Gap granitoid gneiss, is less voluminous than Shawinigan magmatism; a difference that mirrors their relative proportions elsewhere in the orogen. Ottawan metamorphism is recorded by growth of new zircon rims around magmatic core domains in several samples and spans a period of ca. 25 m.y. from ca. 1035 to 1010 Ma. The timing of the older and younger magmatic suites from the southern French Broad massif correlate to well-established times of Shawinigan and Ottawan magmatism and metamorphism in other Grenville-age terranes within the U.S. (e.g., Appalachian inliers, Adirondacks).

Alternative Demographic Models for Two Populations of the Seal Salamander, Desmognathus monticola

Variation among desmognathan salamanders in the timing of the female reproductive cycle is poorly understood. Although nesting tends to be seasonal, in the warmer months, females may not reproduce on a strictly annual cycle, but on a biennial or irregular schedule. In the present report, I examine the ramifications of annual and biennial female reproductive schedules on demography in two populations of Desmognathus monticola in the southern Blue Ridge Mountains of southwestern North Carolina. Provisional demographic models for each are developed based on published data on age structure, growth and developmental rates, and fecundity in the populations in question. The models indicate that biennial reproduction would require higher first-year survival than annual reproduction, at levels that appear tenable given our understanding of the ecology of nesting females and larvae of this species.

Immediate Effects of Prescribed Fire on Sub-Surface Water Quality in a Managed Yellow Pine Forest

Although prescribed fire is a forest management tool annually applied to nearly one million hectares across the southeastern United States, little is known about how prescribed fire influences soil water quality in the region. Sub-surface pools of nitrogen (N) and phosphorous (P) are important indicators of ecosystem response to disturbance and are likely modified, at least temporarily, by fire. We undertook a five-month study to examine sub-surface nutrient concentrations and pH in a managed yellow pine (Pinus sp.) forest before and after a low-severity dormant season prescribed fire in the Southern Blue Ridge Mountains of South Carolina. Between February and July 2019, soil solution was collected weekly from a 30 cm porous cup suction lysimeters and analyzed for ammonium (NH4+), nitrate (NO3-), and orthophosphate (PO43-), as well as pH. We compared the five-month mean and maximum nutrient concentrations and pH to quantify the immediate effects of prescribed fire. The prescribed fire caused significant pH buffering towards neutrality in burned transects relative to the control. There was no change in soil solution NO3-. The prescribed fire caused a significant increase in maximum NH4+ (18.0 mg/L) and PO43- (6.6 mg/L) concentrations. Post-fire NH4+ concentrations reached a maximum of 18.0 mg/L before declining three weeks post-fire. PO43- concentrations in burned stands reached a maximum of 6.6 mg/L and remained elevated for four weeks post-fire. Nutrient leaching was minimal due to complexion to soil cations and ground water uptake from regenerating vegetation at the onset of the growing season. The PO43- and NH4+ pulses in this study are likely influenced by fire-induced changes to soil chemistry and future studies should examine the homogeneity of pH buffering and nutrient pulses across the burned landscape.

Invasion and high-elevation acclimation of the red imported fire ant, Solenopsis invicta, in the southern Blue Ridge Escarpment region of North America.

The red imported fire ant (Solenopsis invicta) is a non-native invasive species that rapidly spread northward in the United States after its introduction from South America in the 1930s. Researchers predicted that the northward spread of this invasive ant would be limited by cold temperatures with increased latitude and greater elevation in the Blue Ridge Escarpment region of the United States. The presence of S. invicta at relatively high elevations north of their projected limits suggests greater cold tolerance than previously predicted; however, these populations might be ephemeral indications of strong dispersal abilities. In this study, we investigated potential physiological adaptations of S. invicta that would indicate acclimation to high elevation environments. We hypothesized that if S. invicta colonies can persist in colder climates than where they originated, we would find gradients in S. invicta worker cold tolerance along a montane elevational gradient. We also predicted that higher elevation S. invicta ants might incur greater physiological costs to persist in the colder climate, so we measured colony lipid content to assess health status. For comparison, we also collected physiological temperature tolerance data for the co-occurring dominant native woodland ant Aphaenogaster picea. We found that S. invicta occurring at higher elevations exhibited greater physiological tolerance for cold temperatures as compared to lower-elevation conspecifics-a cold tolerance pattern that paralleled of the native A. picea ants along the same gradient. Both S. invicta and A. picea similarly exhibited lower thermal tolerances for colder temperatures when moving up the elevational gradient, with A. picea consistently exhibiting a lower thermal tolerance overall. There was no change in S. invicta colony lipid content with elevation, suggesting that greater metabolic rates were not needed to sustain these ants at high elevations.

Watershed- to continental-scale influences on winter stormflow in the Southern Blue Ridge Mountains

Spatial and temporal influences on the winter (December-March) stormflow characteristics of fifteen United States Geological Survey (USGS)-gaged watersheds in the Southern Blue Ridge Mountains are identified: (1) watershed-scale differences in geomorphology; (2) continental-scale teleconnections during periods of wetness/dryness (based on the relative amount of winter precipitation over a consistent 20 year dataset); and (3) land cover in the context of soil parent material (e.g., development on alluvium/colluvium). Multiple regression was used to determine how much variance could be explained in five hydrologic variables describing the flashiness of peak flow (three original metrics), total seasonal flashiness (Richards Baker flashiness index), and the ratio of total winter stormflow to total discharge (the stormflow index). Models were constrained to three uncorrelated (|0.65|) variables to prevent overfitting to the dataset. Average-, dry-, and wet-years were subset using the z-scores for winter precipitation derived from the 4 km monthly PRISM (Parameter-elevation Relationships on Independent Slopes Model) dataset, for the period of 1986–2006. Relief, slope, and landscape connectivity explain the majority of explained variance in all five of the hydrologic variables during all time periods. During dry-, average-, and wet-years, atmospheric circulation patterns (i.e., North Atlantic Oscillation and Pacific/North American Pattern) explain more variance than total seasonal precipitation (PRISM), which is not true in the majority of the all-years models. Land cover explains only a small portion of the variance in regional stormflow and only when sub-divided based on soil parent material. Results provide a framework for connecting watershed-scale characteristics to regional- and continental-scale processes.

Petrology and geochronology of Mesoproterozoic basement of the Mount Rogers area of southwestern Virginia and northwestern North Carolina: Implications for the Precambrian tectonic evolution of the southern Blue Ridge province

This study was supported by awards from the Educational Geologic Mapping Program administered by the U.S. Geological Survey (USGS) to George Washington University (GWU). The research also benefited from additional support provided by the USGS Appalachian Landscape Project.

Biogeographical evidence for common vicariance and rare dispersal in a southern Appalachian harvestman (Sabaconidae, Sabacon cavicolens)

AbstractAimSpecies or higher taxa that are obviously dispersal‐limited, but which occupy large geographical distributions, represent a biogeographical paradox. Dispersal must have happened, likely under special and infrequent environmental conditions, but details have been lost to history. The overarching goal of our research is to understand the details of a ‘common vicariance, rare dispersal’ biogeographical history in a widespread but habitat‐specialized harvestman species (Sabacon cavicolens) with a southern Appalachian centre of distribution.LocationEastern North America, southern Appalachians.MethodsWe assessed cryptic speciation using mitochondrial and nuclear gene DNA sequence data, testing alternative delimitation hypotheses using multispecies coalescent analyses. We also tested whether riverine barriers are associated with mitochondrial genealogical structuring, focusing on multiple rivers in the southern Blue Ridge physiographical province. Finally, we conducted population genetic analyses to assess female‐based range expansion out of the southern Blue Ridge.ResultsGenetic analyses suggest a large number of species‐level lineages within S. cavicolens, although we prefer a more conservative three‐species hypothesis. These putative species are geographically cohesive and allopatric (Ozarks, Cumberland Plateau, southern Blue Ridge), with the Blue Ridge species including multiple divergent mitochondrial haplogroups. Several genealogical breaks in the Blue Ridge species coincide with riverine barriers, separating mostly allopatric mitochondrial lineages. Contrasting with evidence for constrained gene flow and vicariance, two Blue Ridge haplogroups reveal extensive range expansion both northwards and westwards, resulting in the widespread distribution of closely related haplotypes, and occasional sympatry of dispersive haplotypes.Main ConclusionsHidden beneath the apparently widespread distribution of a single species is a history of old vicariance separating geographically disjunct cryptic species. How these lineages came to occupy such disparate geographies is illustrated by dynamics within the Blue Ridge species, where both in situ vicariance and long‐distance dispersal have shaped a ‘common vicariance, rare dispersal’ biogeographical history.

Relative Growth Rates in Three Species ofDesmognathus(Amphibia: Plethodontidae)

Abstract: Observed life histories of animals reflect trade-offs among growth, reproduction, and survival that serve to maximize fitness under particular environmental regimes. Body size and age at first reproduction, as expressions of growth and developmental rates, are key trade-off elements. I estimated relative growth rates in three species of desmognathine salamanders that vary markedly in body size and habitat associations. Sampling was conducted in two assemblages of the species in the southern Blue Ridge of North Carolina. The species, ranked from larger to smaller, were Desmognathus quadramaculatus, D. monticola, and D. ocoee. An existing skeletochronological database served as a source of age estimates in salamanders for which standard lengths had been recorded. Body masses were estimated for these individuals from regressions of mass on standard length. Relative growth rates were estimated by the Gompertz model for growth in standard length and body mass, and by the von Bertalanffy model for gr...

Early Clonal Survival and Growth of Poplars Grown on North Carolina Piedmont and Mountain Marginal Lands

The western half of North Carolina has abundant marginal pasturelands that vary greatly in altitude. Studies have demonstrated high Populus productivity on coastal plains and eastern Piedmont regions. Our objective was to identify best-performing Populus clones on marginal pasturelands representing upper Piedmont (Salisbury, 215 m above sea level, m.a.s.l.), northern Blue Ridge Mountains (Laurel Springs, 975 m.a.s.l.), and southern Blue Ridge Mountains (Mills River, 630 m.a.s.l.). At Salisbury, height and basal diameter (BD) were significantly related to clones (p < 0.0001), and some clones were affected by clone-spacing interaction while spacing affected aboveground wood volume significantly (p < 0.0001). At Mills River, clonal survival (p < 0.0011), height, and volume (p < 0.0051) varied with contrasting significance of some clonal differences between spacings. At Laurel Springs, survival varied among clones in 1 m × 1 m spacing (p = 0.003) but not 2 m × 2 m spacing while heights and volumes differed in both spacings (p < 0.0058). Clone 185 was consistently in the top 10 % for height, BD, and survival at all sites and spacings while other clones performed variably. Height-BD regressions were affected by clones, spacing, and sites. Volume had no clear correlations with precipitation, photosynthetically active radiation, temperature, and altitude across sites while height correlated with precipitation. Our results compared favorably with published results in other US regions, and show short rotation poplars have efficacy in Piedmont and mountain regions if the right clones in terms of growth/productivity, survival, and disease resistance are selected. Larger clonal performance variations are expected as competition increases, and highlight importance of experimentally determining suitable clones for specific sites.

Historical erosion and sedimentation in two small watersheds of the southern Blue Ridge Mountains, North Carolina, USA

Sediment bodies produced during historical periods of human land use, sometimes referred to as legacy sediment, may be found in various locations within drainage basins, and potentially remobilized by hydrogeomorphic processes accompanying land use change. The amounts and locations of stored legacy sediment can be significant factors in modern drainage basin function and should be accounted for when possible. In this study, late nineteenth-century erosion and sediment storage were investigated and used to construct approximate sediment budgets for two small Blue Ridge Mountain drainage basins in North Carolina (USA). Erosion was quantified using a distributed implementation of the Universal Soil Loss Equation (USLE), and calibrated on the separate bases of soil profile truncation data and recent published rates for long-term erosion in the region. Sediment yield information was reconstructed from pond sediments trapped behind a mill dam. Alluvial sediment storage was quantified using field studies of streambank and floodplain sediment profiles and digital elevation data. Colluvial storage was calculated as a residual in the sediment budget, and further evaluated using soil profile studies of footslope deposits, and soil survey maps. The proportions of erosion accounted for by the different budget terms in the most reliable budget are: 28% sediment yield (i.e., a sediment delivery ratio of 0.28), 69% colluvial storage, and 3% alluvial storage. Blue Ridge basins with low levels of ground disturbance erode like Piedmont basins at high levels of ground disturbance, primarily due to higher slope angles. Sediment delivery ratio is high relative to those given for much larger basins in the adjacent and more frequently studied Piedmont province, and generally in accordance with published sediment delivery curves that reflect higher hydrogeomorphic connectivities within smaller basins. Low values for alluvial storage in Blue Ridge basins may be explained by high sediment transport within steep channels. Colluvial storage values have high uncertainties because of the well known problem of error accumulation in residual budget terms. Field data on colluvial deposits reported here are not sufficient to correct for this problem, and in general, the acquisition of accurate field data on historical colluviation remains an important methodological issue in historical sediment budgeting.

Introduction

Introduction Hilda Kurtz and Deepak Mishra Dear Readers, We are delighted to introduce the latest issue of Southeastern Geographer, which also marks the beginning of our tenure as editors. This issue contains a very thoughtful special forum on the Charleston massacre of June 2015. Five short essays by seven geographers reflect on the implications of the murder of nine African Americans attending bible study in church by a self-proclaimed white supremacist. Different lenses on the tragedy dovetail in compelling ways. We hope that the forum encourages reflection and perhaps debate about how to understand and respond to ongoing racial violence. The special forum is followed by five articles showcasing the diverse nature of our discipline from human to physical geography. Tyner’s article analyzes the speeches of Malcolm X to draw out new understandings of the Black freedom fighter’s legacy. Specifically, Tyner urges readers to rethink Malcolm as at once “a critical theorist of geography and a radical political philosopher.” He focuses on Malcolm’s attention to geographies of the South in the latter’s geopolitical philosophy. Malcolm’s geographical critiques de-emphasized Southern exceptionalism, Tyner shows, and argued that “racial oppression and exploitation were constitutive of U.S. society as a whole.” Markley and Sharma examine the politics surrounding a residential building demolition in suburban Roswell, Georgia as a case of revanchist (sub)urbanism in which working class, nonwhite residents are displaced in the name of revitalizing suburban space. This intriguing case study considers such changes in the suburban landscape in tension with ideas of (sub)urban entrepreneurialism and New Urbanism. Hardy, Hepinstall-Cymerman, and Fowler partnered with two local land trusts to develop a priority map for conservation easement recruitment in the Upper Oconee watershed in northeastern Georgia. In the U.S., more than half of threatened and endangered species and their habitats are estimated to be located on private land, yet few land trusts have the staff and technical skills necessary to conduct conservation assessments of their jurisdictions. Their study provides a framework for partnerships between academic researchers and land trusts working on increasing the effectiveness of private land conservation. Kennedy investigated the possible impact of breached historic mill ponds in the southern Blue Ridge region in terms of their potential to act as sediment sources, elevating regional sediment yield values. Her study demonstrated that small mill ponds were potentially scattered throughout the southern Blue Ridge, impounding low-order streams (2nd and 3rd), and that the abandonment and breaching of these dams resulted in the remobilization of sand-, silt-, and clay-sized particulates. [End Page 3] Brown, Ellis, and Bleakney assessed tornado frequency characteristics and vulnerability within 100 km of three major cities in Tennessee—Nashville, Memphis, and Knoxville. In the past ten years, Tennessee has recorded the highest number of tornado-related fatalities of all states. They found that three cities experienced an annual peak in tornadoes during the spring months; however, tornadoes in Memphis were spread out across more tornado days than in Nashville and Knoxville. Memphis also recorded the greatest number of fatalities among the three cities. Their study help provide insight on how tornado characteristics and associated vulnerability are changing on a regional scale. In short, the articles in this issue demonstrate the rich breadth of inquiry that makes contemporary academic geography so invigorating. We welcome your feedback. Best regards, Hilda Kurtz and Deepak Mishra MEET THE TEAM Greetings Members of SEDAAG, As in the incoming editors of Southeastern Geographer, we would like to introduce ourselves and our vision for the journal, and invite you to contribute in many ways and sundry to SEDAAG’s flagship regional journal. It is a privilege and an honor to continue in the footsteps of past editors Jim Wheeler, Derek Alderman, Scott Lecce, Graham Tobin, Robert Brinkmann, David Cochran, and Andy Reese. Their hard work and savvy innovations, including the move to quarterly publication, the linkage with UNC Press, the inclusion in Project Muse, and the publication of timely and well-received special issues, have positioned the journal as the most cited regional geography journal out there. We wish to thank the SEDAAG leadership for entrusting us to manage Southeastern Geographer for the...

Anthropic signatures in alluvium of the Upper Little Tennessee River valley, Southern Blue Ridge Mountains, USA

Abstract Human activities have become important influences on the fluvial systems of eastern North America since post-colonial settlement. This research identifies post-settlement anthropic signatures in alluvial sediments in the Upper Little Tennessee River, USA. Agricultural and mining activities were scattered and discontinuous in this relatively remote region of the Southern Blue Ridge Mountains. We compared physical and chemical characteristics of sediments in post-settlement and pre-settlement stratigraphic units at three separate sites. Chronologies were calculated using non-linear power functions based on radiocarbon and optically stimulated luminescence ages, as well as dates from 137 Cs and historical records. These chronologies suggest that sedimentation rates increased with time during the post-settlement period but decreased with time during the pre-settlement period. In addition, long-term average sedimentation rates are one order-of-magnitude higher in the post-settlement time than in the pre-settlement time. Sediment becomes finer upward through the pre-settlement unit but coarsens-upward in the post-settlement unit. Statistical analyses on adsorbed elemental concentrations suggest that three elements (Ca, Hg, Pb) clearly differentiate sediments between pre-settlement and post-settlement periods. The identified anthropic signatures thus include higher sedimentation rates, coarser sediment texture, and higher concentrations of the three elements in the post-settlement units. These characteristics likely reflect human activities such as commercial timber harvest and scattered gold mining in the late 19th and early 20th century, modern agricultural practices, and urbanization since the 1970s. Findings of this study demonstrate significant impact on fluvial systems in regions with very limited history of intense human activities. This history stands in stark contrast to other parts of the world, like Europe and Asia, that record thousands of years of anthropic impact.

Nineteenth-century sediment yields from the Southern Blue Ridge Mountains

Land-use change can dramatically alter soil erosion and sediment yield in watersheds. This paper describes late 19th-century sediment yield reconstructed for two small, low-order catchments in the Southern Blue Ridge Mountains of North Carolina at a time when each catchment had been partially cleared for agricultural activities and/or timber harvest. Historical sediment yield values are compared and contrasted to modern values obtained for the adjoining and better-known Piedmont province, and to modern values recorded in both provinces. The results indicate that had Blue Ridge land clearance equaled that of the Piedmont, historical sediment yield values would have been substantially higher than those recorded for the Piedmont. Secondly, despite differences in geology, physiography, and land-use intensity, sediment yield values trend similarly in both Blue Ridge and Piedmont regions where 19th-century agriculture and logging were replaced by 20th-century reforestation. Although early slope stabilization resulted in lower sediment yield, there was a time lag between slope stabilization and a return to pre-disturbance sediment yield in small catchments in both physiographic provinces. The remobilization of anthropogenic sediment stored in small catchments has been as influential in the Blue Ridge as in the Piedmont in terms of 20th-century fluvial sediment dynamics.

Downstream geomorphic variation and local bedrock influence of a steep transitional river: Blue Ridge to Piedmont, South Carolina

Spatial patterns in geomorphic variations are examined in a river transition from the Southern Blue Ridge to the Piedmont physiographic regions. Downstream hydraulic geometry (DHG), fining of bed material, and changes in reach-scale channel-bed morphology (bedforms) were sampled and analyzed. DHG power functions were well developed (r2 > 0.75 for channel area, width, and depth). Bed material showed a general downstream exponential decrease in caliber (from 940 mm to sand). However, variations within the general downstream trends reflect local variations and a rapid transition in hydraulic variables and bedforms at a key zone with substantial tributary inputs, decreases in slope, and a punctuated longitudinal profile. Structurally controlled bedrock knickpoints are associated with anomalous spatial patterns of bedforms and can be distinguished through relationships between dimensionless sediment transport capacity and sediment supply using a sediment regime diagram that is independent of drainage area. Plots of relative grain submergence (R/D84), relative form submergence (R/H), Darcy–Weisbach friction factor (f), and slope vs. area also reveal trends that suggest local factors that are missed by downstream hydraulic progressions. The findings of this study corroborate the utility of scale-independent methods, especially in mountain or transitional environments where fluvial controls may be longitudinally sporadic.

Modeling stream-bank erosion in the Southern Blue Ridge Mountains

Deforestation, followed by soil erosion and subsequent deposition of alluvium in valleys, played a critical role in the formation of historical terraces in much of the Southern Blue Ridge Mountains. Such terraces add a significant amount of sediment to the tributaries of the region as streams laterally erode the terrace banks. This study examined the contribution of total sediment yield derived solely from eroded stream banks in small watersheds (<20 km²), using floodplain widths as proxies for long-term lateral erosion rates. The raw data were derived from watersheds with different land covers (Coweeta Creek and Skeenah Creek watersheds in the Upper Little Tennessee River basin). Bank-derived sediment yield estimates were modeled in a Geographic Information System, using linear regression to relate floodplain widths and erodible terrace bank heights. We found total stream length to be a good predictor of both lateral erosion rates and erodible bank heights. Land cover, basin/network morphometrics, and reach-scale stream conditions were not good predictors. Modeled lateral migration and sediment yield results compare favorably to empirical measurements from five independent watersheds in the region. Modeled estimates fall within ±50% or better of the observed values, at 16.33 to 25.02 t km−2 yr−1.