Extracting habitat features from hyperspectral imagery of the Duplin River watershed at the Sapelo Island National Estuarine Research Reserve

As a joint project of the NOAA Environmental Cooperative Science Center and the Georgia Coastal Ecosystems NSF-LTER, aerial, hyperspectral AISA imagery at 1 m resolution was acquired at low tide on the morning of June 20, 2006 for the Duplin River watershed, located entirely within the Sapelo Island National Estuarine Reserve. The Duplin site is a Georgia Coastal Ecosystems LTER focus for integrative studies. Ground truth habitat data, collected within two weeks of the imagery, included: salt marsh communities (plant species cover, canopy height, biomass, soil properties, invertebrate densities) and open water (chlorophyll a, total suspended matter, CDOM). Additional salt marsh and upland hammock characterizations were done in 2006 and 2007. Masking and classification procedures were used to separate different habitats (water, intertidal mudflats, herbaceous salt marsh, and upland hammock). Habitat classifications such as phytoplankton chlorophyll, salt marsh vegetation biomass and species cover, and mudflat algal chlorophyll) were produced from the imagery using ENVI software. Map products and statistical summaries of classified habitat attributes will be presented. For example, we estimated an average marsh plant biomass of 1205 g dry wt/m2 and total marsh plant biomass within the watershed of 1280 MT dry wt. The imagery products are new data layers for a comprehensive GIS of the Duplin watershed. Spatially explicit classifications potentially offer greater accuracy in scaling plot based sampling measures to an entire watershed unit. This understanding is difficult to obtain from conventional quadrat sampling because marsh ecosystems are heterogeneous on multiple spatial scales. Additionally, revealed patterns can lead to new hypotheses and experimentation.