Vegetation classification and mapping project report, Curecanti National Recreation Area

Tendick, Amy; Coles, Janet; Williams, Peter; Bradshaw, Ginger; Manis, Gerald; Wight, Aneth; Wakefield, Gary; Evenden, Angie

The Northern Colorado Plateau Inventory and Monitoring Network, with the support of the U.S. Geological Survey - National Park Service Vegetation Mapping Program described and mapped vegetation at Curecanti National Recreation Area (CURE). This collaborative effort involved many project partners, particularly CURE natural resources staff, the Western Region office of NatureServe, engineering-environmental Management, Inc., and their cooperators. The mapping area is 48,639 hectares (120,189 acres), encompassing the entire recreation area as well as an environs of adjacent public and private lands. Ecologists and photointerpreters worked to identify plant associations for CURE and determine how best to map them using 1:12,000 scale, true color aerial photography and digital orthophotography. The team collected vegetation and environmental data from 281 vegetation classification plots and 99 observation points. Supplemental fuels data were collected during the project in sagebrush, Gambel oak, mixed mountain shrubland, pinyon-juniper, ponderosa pine, Douglas-fir, and quaking aspen communities. Assessment of map accuracy entailed sampling 1,037 additional data points. Fieldwork and mapping were completed between 2001 and 2005. Analysis of the plot data revealed 131 National Vegetation Classification plant associations, alliances, or ‘park special’ vegetation types within the recreation area and environs, 56 of which are shared with the adjacent Black Canyon of the Gunnison National Park. Twenty-one associations were documented exclusively from accuracy assessment data, the remainder from vegetation plots, observation points, and field notes. Vegetation and land use were interpreted to as detailed a level as possible from high-resolution, 9” x 9” stereo pairs of 1:12,000-scale true color aerial photography. Polygons representing vegetation or land use map classes were delineated on Mylar overlays on paper plots of the orthophotographs and transferred to a spatial database. The project used the program standard minimum mapping unit of 0.5 ha with few exceptions. The CURE vegetation mapping project area was divided into 11,133 polygons and 42 map classes. A total of 10,520 map polygons represent 27 natural and semi-natural vegetation map classes. Fifteen land use map classes describe 613 other polygons within the mapping area. Average polygon size across all map classes is 4.4 ha (10.8 acres). Natural and semi-natural vegetation classes cover 43,624 ha (107,796 acres; 89.7% of the project area). Land use/land cover polygons, including roads, agricultural fields, bare ground, open water, and NPS facilities, total 5,015 ha (12,373 acres; 10.3% of the project area). The most widespread vegetation mapping unit is the Wyoming Big Sagebrush Shrubland (S-ARWY, #41) with 1,640 polygons covering 10,870 ha (26,861 acres) or 22.3% of the project area. Map accuracy was assessed within the CURE boundary only. Results from a thematic accuracy assessment of 27 vegetation map classes remaining after accuracy assessment analysis indicated an estimate of 87.3% overall map accuracy (Kappa statistic = 85.7%). Fourteen map classes did not meet the 80% standard for either producer’s or user’s accuracy, but were retained because of their relative rarity and/or value to NRA managers. These map classes are described in the Accuracy Assessment section of this report, as is the justification for retaining them.

Vegetation classification and mapping project report, Curecanti National Recreation Area

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