Imperiled Ecosystems in a Shifting Climate
2016 Atlantic White Cedar Symposium
May 24-26, 2016

Hotel 1620, 180 Water St., Plymouth, MA

Remote Sensing of Forest Type and AWC range in the Great Dismal Swamp and preliminary results of Greenhouse Gas Flux Monitoring

Author: Laurel Gutenberg, George Mason University

Forest degradation, including logging and ditching, has greatly impacted the Atlantic white cedar and Pocosin forested wetland communities in the Great Dismal Swamp (GDS). Today, the maple-gum assemblage has become much more common. Peat that has accumulated under these now rarer communities over thousands of years has oxidized, releasing carbon into the atmosphere.

As part of a larger project, this study uses forest-characteristic ground data and remote sensing images, including multispectral and radar, to map the different forest types in the GDS, as well as to relate GHG flux to conditions and forest type. .
Multispectral and SAR data were used to classify forest type based on spectral signatures extracted from areas of known ground cover in each of five main classes. These known areas were created using a data set collected in 2014 that included tree species and size, and with a detailed shapefile made from private aerial photos. Error matrices were generated for each combination of images and products to determine which works the best for forest classification in the GDS. The resulting AWC range was then compared with historical AWC range published in 1890.

Combinations of data that included multiple seasons added to the overall accuracy of the classification, as did adding radar texture measures. Preliminary GHG flux measurements show more methane released in wetter areas, and show AWC forest areas have a higher average carbon dioxide flux rate than maple and pocosin. The current AWC range shows some correlation with the historic AWC range, but has been altered by ditching and draining as well as logging, fire, storms and other management.

Laurel Gutenberg is a Ph.D. student in the Earth Systems and GeoInformation Sciences program at George Mason University. She received an M.S. in Agroecology from the University of Wisconsin in 2009. As a graduate research assistant, she is working with the U.S. Geological Survey in the Climate and Land-Use Change mission area. Her research interests include remote sensing of ecological properties such as greenhouse gas flux, soil moisture, and biomass.