National Park Service Vegetation Inventory Program: Indiana Dunes National Lakeshore, Indiana

Hop, Kevin; Lubinski, Sara; Dieck, Jennifer; Drake, Jim; Menard, Shannon

The National Park Service (NPS) Vegetation Inventory Program (VIP) is an effort to classify, describe, and map existing vegetation of national park units for the NPS Natural Resource Inventory and Monitoring Program. The NPS VIP is managed by the NPS Biological Resources Management Division and provides baseline vegetation information to the NPS Natural Resource Inventory and Monitory Program. The U.S. Geological Survey (USGS) Vegetation Characterization Program lends a cooperative role in the NPS VIP. The USGS Upper Midwest Environmental Sciences Center, NatureServe, and NPS Indiana Dunes National Lakeshore, have completed the classification and mapping of plant communities of Indiana Dunes National Lakeshore (INDU, also referred to as Lakeshore) and immediate surroundings. Photointerpreters, ecologists, and botanists collaborated to describe National Vegetation Classification (NVC) System plant associations (communities) and determine how best to map them using aerial photographs. The team collected 190 vegetation sampling plots within the Lakeshore project extent. Furthermore, data from 484 accuracy assessment (AA) sites were collected (of which 469 were used to test the vegetation map layer accuracy). These data sets led to the identification of 38 NVC plant communities at the Lakeshore plus several more NVC alliance and formation types that could not be described at the association level. Sixty-seven map classes were developed to map the vegetation and general land cover of INDU and environs, with 56 of them representing vegetation types at various levels in the NVC (association, alliance, and formation). The other 11 map classes depict general land cover; 4 representing non-vegetated land cover and 7 representing developed areas. Features were interpreted using high-quality stereoscopes over light tables and 1:12,000-scale color infrared (CIR) aerial photographs dated October 2004 (fall leaf-change). Polygon units were mapped to 0.5 ha (1.25 acres) minimum mapping unit (MMU) and, for specific wetland map units within the West unit, to 0.1 ha (0.24 acres) MMU. Another set of 1:6,000-scale CIR aerial photographs dated October 2004 were used to aid interpretation mapping of the West unit’s MMU. An ancillary set of 1:12,000-scale true color aerial photos dated April 2005 (leaf-off) covering the entire Lakeshore lands were used for additional reference during mapping. The interpreted data were digitally and spatially referenced, making the spatial database layers usable in geographic information systems (GIS). 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 photograph centers. The INDU vegetation map feature class layer provides 4,023 polygons of detailed attribute data covering 13,259.1 ha (32,764.0 acres), with an average polygon size of 3.3 ha (8.1 acres). Of the area mapped, 3,527 polygons (87.7%) represent NVC vegetation types, encompassing 8,421.8 ha (20,810.6 acres; 63.5%) of the total map extent. With a 400-meter buffer environs, the Lakeshore lands account for approximately 46% of the entire map extent. Summary reports generated from the vegetation map layer indicate forest types dominate the vegetative landscape (NVC types), populating 50.9% of the polygons and covering 61.6% of the area, and are largely dominated by the Black Oak Forest community. A thematic AA study was conducted of map classes representing NVC types. Results present an overall accuracy of 78.2% (Kappa index of 76.9%) based on data from 469 of the 484 AA site data. Most individual map class themes exceed the NPS VIP standard of 80% with a 90% confidence interval.