Variation in the structure, composition, and dynamics of a foundation tree species at multiple scales and gradients
Bhuta, Arvind Aniel Rombawa
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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 pineâ 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.
- Doctoral Dissertations