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Browsing by Author "Bhuta, Arvind Aniel Rombawa"

Now showing 1 - 4 of 4
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    A Denroecological Analysis of Disturbance of Remnant Pinus Palustris, Southeastern Virginia
    Bhuta, Arvind Aniel Rombawa (Virginia Tech, 2006-04-28)
    Pinus palustris Miller (longleaf pine), in Virginia, is at the northernmost extent of its range. During presettlement times, this species occurred throughout the Piedmont and Coastal Plain of Virginia in pure and mixed stands, covering 607,000 hectares. This forest type has since been reduced to 81 hectares or 0.01% of its former range. Around 5,000 individual Pinus palustris remain on six sites in the coastal plains. Seacock Swamp and Everwoods are both sites known to have naturally regenerated Pinus palustris native to Virginia occurring in mixed-species stands. At both sites, I measured height and diameter of all Pinus palustris and cored individuals greater than 10 cm in diameter at breast height. A total of 71 trees were cored; the cores were crossdated and measured and crossdating was verified with the COFECHA program. A strong competition signal within the tree ring records at both sites signified the importance of stand dynamics on Pinus palustris in second-growth loblolly pine stands. These results are probably due to the mix of species within these stands and competition from loblolly pine as both the dominant understory and overstory species. Using Black and Abrams (2003) boundary line method, we calculated release and suppression events from the tree-ring record over the last century and found a very dynamic system. During the 1950s and 1960s, Seacock Swamp experienced major and moderate releases (23% moderate release and 18% major release in the 1950s and 33% moderate release and 49% major release in the 1960s) in response to a diameter-limit cut in 1953. Other major and moderate releases varied at both sites and may be attributed to different forest management practices that were in place throughout the last century however locating historical land use records to validate this was not possible at the present.
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    Geospatial and field-based techniques for physical geography and environmental change
    Swift, Troy Phillip (Virginia Tech, 2023-10-11)
    This dissertation has primarily been an exercise in surveying interdisciplinary opportunities for further research within the doctoral program's overarching mandate of Geospatial and Environmental Analysis. To this end I have dedicated my efforts to the investigation of topics and themes that are relevant to my three specializations: physical geography, biogeography, and geospatial science. I share these efforts in the three following chapters, one of which is already published (Chapter 2), and the other two presented as manuscripts suitable for publication. These themes include historical and present hydrological patterns and drivers, hurricane disturbance of coastal forest, and evaluation of a Wisconsin geosite as a possible candidate for UNESCO Geopark designation. I chose study areas located in the eastern United States, including Appalachia, the Gulf Coast, and the Great Lakes region. Every chapter's work has been supported by an interdisciplinary array of methods with which I have striven to generate high-quality research from excitingly novel perspectives. All of my research has been pursued, and each resultant manuscript has been crafted, using methods and techniques from remote sensing and GIS including in-person fieldwork, smartphonesupported geolocation and photodocumentation, pattern analysis, statistical rigor, and indepth review and citation of extant literature. This research was carried out with deliberately minimal budgets that help offset costs of transportation and labor. I offer this dissertation as the ultimate fruits of my labor while here at Virginia Tech, composed of three interrelated yet reasonably stand-alone manuscript chapters that in turn more specifically address questions within the broader fields of biogeomorphology, dendrotempestology, and finally the geohumanities. Chapter 2 was published in an open-source peer-reviewed journal (Land, 2021: https://doi.org/10.3390/land10121333). My coauthors and I intend to publish the remaining two chapters in peer-reviewed journals. Therefore each manuscript herein provides its own Introduction, Methods, Results, Discussion, Conclusion, and References sections as set forth in the Table of Contents. Chapter 2 is a recently published study of historical beaver activity and hydrological patterns at the rare and imperiled Cranberry Glades Botanical Area, a high-elevation peatland in the Allegheny highlands of West Virginia. We used Lidar and Geomorphon analysis to reconstruct shifting patterns of surface hydrology associated with Beaver ponds and dams over the past three decades. Beavers play a large role in the formation and maintenance of peatland conditions and our work provides a novel method (geomorphons) for monitoring beaver activity into the future. In Chapter 3, we take advantage of wind-damaged leaning pine trees to reconstruct characteristics of landfalling Hurricane Sally (2020) along the Gulf coast of Florida/Alabama (USA). We employed a smartphone to measure and record the direction of lean on 556 pine trees in five sites in the eyewall-struck region. Using geometric analysis, we were able to locate the geographic center of the storm and the position and size of the area of highest speed winds in Sally's eyewall. We validated our results with independent data from official sources and found that our simple field-based analysis was surprisingly accurate. We think that our low-cost and relatively low-tech approach may be useful to inform hindcasts, provide quality input to models of future stand-damaging events, and even to enhance teaching and outreach efforts. Chapter 4 represents research aimed at producing an inventory and assessment of the Baraboo Hills in south-central Wisconsin (USA) as a potential candidate for a UNESCO Geopark. The basis for designation is a geographical area that contains geological heritage of international significance, but such a park's fuller mission according to its website is to "explore, develop and celebrate the links between that geological heritage and all other aspects of the area's natural, cultural and intangible heritages." We followed a published method, including field study, to inventory and assess 62 sites in and around the Hills for their scientific, educational, and touristic merit, and their risk of degradation. We provide these data and through spatial analysis, a proposed perimeter of the area that would benefit from unified protection.
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    Leveraging the Landsat Archive to Track Understory Evergreen Shrub Expansions in the Coweeta Basin, North Carolina
    Donahoe, Daniel James (Virginia Tech, 2022-06-28)
    Invasive species introductions, namely the chestnut blight fungus (Cryphonectria parasitica) and hemlock woolly adelgid (Adelges tsugae), have permanently altered the overstory canopy of Appalachian forests by causing the dramatic die-offs of two ecologically significant tree species, American chestnut (Castanea dentata) and eastern hemlock (Tsuga canadensis). These canopy dominants once had significant roles in regulating understory communities. The loss of these trees, along with fire suppression, has driven two common evergreen shrubs, rosebay rhododendron (Rhododendron maximum) and mountain laurel (Kalmia latifolia), to expand and proliferate in areas where they were once restricted. These two common shrubs are recognized agents of change in Appalachian forests because of their abilities to modify soil seed banks, regulate light, and alter the local soil chemistry. This study documented evergreen shrub expansion across the Coweeta Creek basin over the past 36 years analyzing changes in winter greenness using harmonized multi-decadal archives of Landsat imagery. We found the greatest change in winter greenness in relatively dry areas: higher elevations (1275–1300 m), steeper slopes (33°–35°), southward aspects, and far from streams (600–800 m). Historical field data collected in three unmanaged watersheds at Coweeta showed a simultaneous decrease in T. canadensis and increase in R. maximum. We also documented the decline of a xerophytic canopy tree species, pitch pine (Pinus rigida), and an associate understory shrub, K. latifolia. Our analysis of the influence of terrain variables on evergreen shrub expansion allowed us to determine which of the two species was expanding in various locations with reasonable certainty. This study provides spatially explicit data on the expansion of two evergreen shrub species at the Coweeta Hydrologic Laboratory that could be used to pinpoint areas for future management interventions. 
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    Variation in the structure, composition, and dynamics of a foundation tree species at multiple scales and gradients
    Bhuta, Arvind Aniel Rombawa (Virginia Tech, 2011-12-06)
    Scientists and land managers often focus on the Southeastern Plains and Coastal Plain of the southeastern United States when considering the ecology, restoration, and management of longleaf pine (Pinus palustris P. Mill.) communities and ecosystems. However, the range of this foundation tree species and its associated communities and ecosystems also extend into the Piedmont and Montane Uplands: the Piedmont of Alabama, Georgia, North and South Carolina and Virginia; the Ridge and Valley of Alabama and Georgia; and the Southwestern Appalachians of Alabama. The composition, structure, and dynamics of Piedmont and Montane Uplands longleaf pine communities have been understudied compared to their Southeastern Plains and Coastal Plain counterparts, and knowledge is based on historical accounts and a handful of studies at site-specific scales. The biogeography and ecology of Piedmont and Montane Uplands longleaf pine communities differ significantly from those in the Southeastern Plains and Coastal Plain. My research combines geospatial and ecological approaches to provide insights on current composition, structure, and dynamics of longleaf pine communities in the Southeastern Plains, Piedmont, and Ridge and Valley at multiple scales and highlights differences and similarities with communities in the Coastal Plain. The Piedmont and Montane Uplands longleaf pine communities showed high variation in canopy tree diversity compared to those in the Coastal Plain. Longleaf pine was sometimes the only canopy tree, while in other communities longleaf pine was one constituent in a mixed oak-pine canopy. My study showed that longleaf pine communities were not just restricted to south-facing slopes as previously thought, but were found on northwestern-facing slopes as well. Analysis of tree rings across my study sites showed that as longleaf pine approaches its northern range margin in the Piedmont and Montane Uplands, its radial growth is restricted by minimum temperature especially at longleaf pine's elevational, latitudinal, and longitudinal extremes; at all sties radial growth was influenced by drought and precipitation. At the local scale, I found that an Alabama Piedmont longleaf pine community showed a diameter-class distribution typical of an old-growth site but contrary to current knowledge, diameter was not a good indicator of age.