Interacting drivers of tree mortality in a rare bottomland oak swamp

Authors: Brahim Laadhar*, Concord University, Tom Saladyga, Concord University
Topics: Physical Geography, Land Use and Land Cover Change
Keywords: Climate, wetlands, GIS, land cover
Session Type: Poster
Day: 4/11/2018
Start / End Time: 3:20 PM / 5:00 PM
Room: Napoleon Foyer/Common St. Corridor, Sheraton, 3rd Floor
Presentation File: No File Uploaded

Riverine forested wetlands develop under unique hydrological conditions characterized by seasonal floods that deposit fine textured, silt and clay, soils. Abrupt changes in the hydrological regime, such as an increase in the frequency or intensity of flooding, can alter plant community composition by favoring species more tolerant of prolonged inundation. Within the Meadow River watershed in southern West Virginia, there is a large wetland complex harboring regionally unique plant communities. An abnormally high rate of tree mortality within the last 15 years, however, has raised questions about the development and resiliency of these rare plant communities, particularly the “bottomland oak swamps.” Our objective was to identify potential drivers of tree mortality through the use of Geographic Information Systems (GIS) and an analysis of trends in hydroclimatic variables, including temperature, precipitation, vapor pressure deficit, and streamflow. We hypothesized that increased runoff and moisture availability within the watershed has raised the water table during the growing season. Land cover change analysis indicates an approximately 3% reduction in forest cover between 2001 and 2011, while shrubland and herbaceous cover increased an equal amount during the same time period. Vapor pressure deficit was the best indicator of hydroclimatic change with a significant decline (i.e., negative shift) in growing season values beginning in 2000. This timing of land cover change and reduction in atmospheric “drying power” suggests that a moisture threshold was crossed, which may have led to high levels of tree mortality during the first decade of the 21st century.

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