PARENT SESSION
Poster Session # 5: GIS and Remote Sensing.

Monday, August 4 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Assessing the spatial distribution of Phragmites australis on a Mid-Atlantic barrier island.

Russ, Andrew^{*,1, 3}, Bachmann, Charles², Fusina, Robert², Burke, Joseph³, ¹ USDA Agricultural Research Service, Beltsville, MD³ University of Maryland, College Park, MD² Naval Research Laboratory, Washington, D.C.

ABSTRACT- Phragmites australis (Common Reed) has become a concern to ecologists due to its increasing expansion into wetland areas displacing grass species such as Spartina patens and Spartina alterniflora. Phragmites was introduced to Hog Island, Virginia, a Mid-Atlantic coastal barrier island, in the early 1990s. Hog Island is a part of the Nature Conservancy's Virginia Coast Reserve, a National Science Foundation Long Term Ecological Research Site (LTER). It is largely free from anthropogenic disturbance and as such it offers a unique opportunity to study environmental factors influencing the spread of an invasive species. The spatial distribution of Phragmites on Hog Island was determined through the use of differential global positioning system (DGPS) surveys, classificaton of PROBE2 hyperspectral imagery, and examination of color infrared (CIR) aerial photography and LIDAR data. A total of 102 Phragmites patches were mapped with DGPS, encompassing an area of 61,740 m². A Mixture Tuned Matched Filter (MTMF) classification of the PROBE2 imagery identified pixels within 79 of the 102 surveyed patches. The 23 patches not identified by MTMF were typically small or sparse, encompassing a total area of 3,080 m². The LIDAR data suggest a greater than 500% increase in Phragmites coverage on a portion of the island over the last 5 years. The influence of overwash disturbance, edaphic factors and interspecific competition on the distribution of Phragmites was examined. Areas of overwash disturbance were determined to be likely points of establishment. Phragmites appears to have initially spread along the edges of inland lakes and into interior areas with harsher edaphic conditions through means of clonal integration. Subsequent dispersal of propagules lead to the emergence of isolated patches further inland along the Myrica cerifera thicket/marsh interface.

Key words: hyperspectral remote sensing, phragmites australis, lidar