Vegetation mapping at Cape Hatteras National Seashore

McManamay, Rachel; Heath, Sarah; Baron, Lisa

The Southeast Coast Network (SECN) worked with the support of the National Park Service (NPS) Vegetation Inventory Program (VIP) to describe and map vegetation at Cape Hatteras National Seashore (CAHA). This mapping effort was accomplished through collaboration with the Southeast regional office of NatureServe (Raleigh/Durham, NC). The mapping area is 11,749 hectares (ha) encompassing the entire boundary of CAHA and an additional buffered area of adjacent lands. NatureServe ecologists identified plant associations for CAHA and a remote sensing specialist from the SECN completed the vegetation mapping using 1:12,000-scale, color infrared aerial photography and digital orthophotography. NatureServe collected vegetation and environmental data from 40 vegetation classification plots, and the remote sensing specialist assessed 111 observation points. Two Student Conservation Association interns hired by the SECN conducted an accuracy assessment (AA), which entailed sampling 450 additional points. Fieldwork and mapping were completed between 2005 and 2014. A total of 27 map classes were developed to map the vegetation and general land cover of CAHA and surroundings, including the following: 13 map classes representing natural/semi-natural vegetation at the association level in the National Vegetation Classification System (NVCS), and 14 map classes representing non-vegetated units (e.g., open water bodies, buildings, roads, etc.). Features were interpreted using 1:12,000 scale digital color infrared aerial photography (flown 31 May 2009) through heads-up-digitizing in ArcGIS (Version 10.0, © 2010 Environmental Systems Research Institute, Redlands, California). Polygons were mapped to a 0.5-ha minimum mapping unit (MMU). A geodatabase containing various feature-class layers and tables show the locations of vegetation types and general land cover (vegetation map), vegetation plot samples, AA sites, project boundary extent, and aerial photographic centers. The feature-class layer for the CAHA vegetation map provides 2, 437 polygons of detailed attribute data covering 11,749 ha, with an average polygon size of 3.6 ha. Of the area mapped, 1,924 polygons (79.0% of all polygons) represent natural/semi-natural vegetation types in the NVCS, encompassing 7,402 ha, 63% of the total map extent. Summary reports generated from the vegetation map layer indicate that the Atlantic Coast Interdune Swale is the most prominent map class in the vegetated landscape (488 polygons covering 2,050 ha), with Needlerush High Marsh also covering a considerable portion of the park (408 polygons totaling 1,273 ha). A thematic AA study was conducted on the 13 map classes within the boundary of CAHA representing floristic types within the NVCS. Results present an overall accuracy of 80.1% (Kappa statistic = 69.9%) based on data from 450 AA sites.

Vegetation mapping at Cape Hatteras National Seashore

Series

Collections