Characterization of a forest-grass ecotone on a Southern Appalachian bald, Whitetop Mountain, Virginia, USA, using remotely-sensed imagery

Authors: Ryley Harris*, Virginia Tech, Lisa M Kennedy, Virginia Tech, Thomas J Pingel, Virginia Tech
Topics: Biogeography, Field Methods, Remote Sensing
Keywords: Unmanned Aerial Systems, Southern Appalachian bald, ecotone
Session Type: Paper
Day: 4/4/2019
Start / End Time: 9:55 AM / 11:35 AM
Room: 8222, Park Tower Suites, Marriott, Lobby Level
Presentation File: No File Uploaded

Southern Appalachian Balds, grass- or shrub-dominated plant communities restricted to windswept rocky summits >1200m, are globally rare ecosystems that host rare, endangered, and threatened species contributing both to regional biodiversity and to unique recreational opportunities. Lacking a climatic treeline in this region, the origins and maintenance of these communities have long been debated with a focus on both environmental and anthropogenic factors. Some balds were formed by historical logging, while many others may be relicts of alpine vegetation of the Pleistocene glacial episode. Many balds appear to have been maintained as treeless systems by disturbances such as fire and grazing. These balds are presently threatened by encroachment of surrounding forests in the absence of such disturbances and possibly influenced by climate change. Managed balds are kept open through burning, mowing, and grazing.

This project investigates the grassy bald (~1520–1645m) at Whitetop Mountain, Virginia. It appears to have been enlarged by historical logging, though the presence of rare, light-demanding species is evidence of its pre-European origin. It has been maintained by frequent burning in recent decades. We aim to document the dynamics of forest encroachment on Whitetop using imagery from sensor-equipped small Unmanned Aerial Systems (sUAS), LIDAR, and historical aerial and satellite photography. Our objectives are to characterize the vegetation along with forest-grassland ecotone, quantify recent tree recruitment, and identify areas of encroachment. Our results will provide insights for managers of this sensitive mountaintop ecosystem and may be generalizable to others.

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