National Park Service Vegetation Inventory Program: Saint Croix National Scenic Riverway

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 (I&M) Program. The NPS VIP is managed by the NPS Biological Resources Management Division and provides baseline vegetation information to the NPS Natural Resource I&M 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, NPS Great Lakes Network, and NPS Saint Croix National Scenic Riverway (SACN) have completed vegetation classification and mapping of the SACN and surroundings. Photointerpreters, ecologists, and botanists collaborated to identify and describe vegetation types within the National Vegetation Classification Standard (NVCS) and to determine how best to map them by using aerial photographs. The team collected 230 vegetation sampling plots within the SACN project extent. In addition, another 63 quick plots were collected to support the development of the vegetation classification. Furthermore, data from 1,290 accuracy assessment (AA) sites were collected (of which 1,257 were used to test accuracy of the vegetation map layer). These data sets led to the identification of 71 floristic types (of which 69 are at the association level and two are at the alliance level) in the NVCS at SACN. Additional vegetation types are recognized at the group level of the NVCS. A total of 68 map classes (including map-class phases) were developed to map the vegetation and general land cover of the SACN and environs, including the following: 61 map classes representing natural/semi-natural vegetation types at various levels in the NVCS, four map classes representing cultural vegetation (e.g., developed lands) in the NVCS, and three map classes representing non-vegetation features (e.g., open-water bodies). Features were interpreted by using high-quality stereoscopes over light tables and 1:12,000-scale, color-infrared aerial photographs dated October 2005 (during fall leaf change). Polygon units were mapped to a 0.5 ha minimum mapping unit. An ancillary set of 1:12,000-scale, true-color aerial photographs dated April 2006 and April 2007 (during leaf-off conditions) covering the entire SACN 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. 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 SACN vegetation map provides 32,751 polygons of detailed attribute data and covers 68,216.7 ha, with an average polygon size of 2.1 ha. Of the area mapped, 30,891 polygons (94.3%) represent natural/semi-natural types in the NVCS, encompassing 51,523.7 ha (75.5%) of the total map extent.

National Park Service Vegetation Inventory Program: Saint Croix National Scenic Riverway

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