Vegetation mapping at Cape Lookout National Seashore

McManamay, Rachel

The Southeast Coast Network (SECN) worked with the support of the National Park Service (NPS) Vegetation Mapping Inventory Program (VMI) to describe and map vegetation at Cape Lookout National Seashore (CALO). This mapping effort was accomplished through collaboration with the Southeast regional office of NatureServe (Raleigh-Durham, North Carolina). The mapping area is 10,715 hectares (ha, 41.4 sqare miles [mi2] or 26,477 acres [ac]) encompassing the entire boundary of Cape Lookout and an additional buffered area. NatureServe ecologists identified plant associations for Cape Lookout and a remote sensing specialist from the network completed the vegetation mapping using 1:12,000-scale, color-infrared aerial photography and digital orthophotography. NatureServe collected vegetation and environmental data from 81 vegetation classification plots, and the remote sensing specialist assessed 110 observation points. Southeast Coast Network staff conducted an accuracy assessment (AA), which entailed sampling 310 additional points. Fieldwork and mapping were completed between 2005 and 2014. Twenty-two map classes were developed to map the vegetation and general land cover of Cape Lookout and surrounding areas. These maps included the following: 13 map classes representing natural/semi-natural vegetation at the association level in the National Vegetation Classification System (NVCS), one map class representing cultural vegetation (e.g., developed) in the NVCS, and eight 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- hectare 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 Cape Lookout vegetation map provides 2,203 polygons of detailed attribute data covering 10,715 hectare (41.4 mi2; 26,477 ac), with an average polygon size of 30.1 hectare (74.4 ac). Of the area mapped, 1,789 polygons (81% of all polygons) represent natural/semi-natural vegetation types in the NVCS, encompassing 5,089 hectare (5,162 ac), or 47.5 % of the total map extent. Summary reports generated from the vegetation map layer indicate the combined map class Outer Banks Coastal Dunegrass / Southern Hairgrass - Saltmeadow Cordgrass - Dune Fingergrass Herbaceous Vegetation / Overwash Dune Grassland dominates the vegetated landscape (1,326 ha [3,276 ac]), with the Southern Atlantic Coast Salt Marsh also covering a considerable portion of the park (993 ha [2,453 ac]). A thematic accuracy assessment (AA) study was conducted on the nine map classes within the boundary of Cape Lookout representing floristic types within the NVCS. Results present an overall accuracy of 88.6% (Kappa statistic = 76.8 %) based on data from 310 AA sites.

Vegetation mapping at Cape Lookout National Seashore

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