Vegetation classification and mapping project report, Bryce Canyon National Park [and associated files]

Tendick, Amy; Kittel, Gwen; Von Loh, Jim; Williams, Peter; Cogan, Dan; Coles, Janet; Wight, Aneth; Wakefield, Gery; Evenden, Angie

The Northern Colorado Plateau Inventory and Monitoring Network worked with the support of the U.S. Geological Survey - National Park Service Vegetation Mapping Program to describe and map vegetation at Bryce Canyon National Park (BRCA). This collaborative effort involved many project partners, particularly the Rocky Mountain Mapping Center of the U.S. Geological Survey, the Western Region office of NatureServe, engineering-environmental Management, Inc., Cogan Technology, Inc., and other cooperators.The mapping area is approximately 23,754 hectares (58,697 acres), encompassing the entire park and an environs of adjacent public and private lands. Ecologists and photo interpreters identified plant associations for BRCA 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 408 vegetation classification plots and 141 observation points between 2005 and 2006 to prepare the initial classification and preliminary vegetation map. During July 2007, team members conducted a vegetation map verification trip to test the field key to plant associations and to suggest minor adjustments to the vegetation map prior to full-scale accuracy assessment. Assessment of map accuracy entailed sampling an additional 902 data plots in the fall of 2007.Analysis of the classification and accuracy assessment plot data revealed 126 National Vegetation Classification plant associations, alliances, or park special vegetation types within the park and environs. Twenty-three associations were documented exclusively from accuracy assessment data, the remainder from vegetation plots and observation points.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 aerial photographs (where signatures were confusing) and with the heads-up digitizing technique (where signatures had high contrast), then transferred to a spatial database. The project used the national program standard minimum mapping unit of 0.5 ha with few exceptions.Forty-nine vegetation and land-use map classes were developed for BRCA which included 6,056 total polygons. Of this total, 5,549 polygons represented 38 natural or semi-natural vegetation map classes covering 94.3% of the mapping project area. Eleven land use/land cover and geologic map classes describe 507 polygons (8% of polygons and 5.7% of the project area). Average polygon size across all map classes was 2.8 ha (7.0 acres). Lands within the Park include 14,614 ha (36,113 acres) or 61.5% of the total project area. The most common map class was the Ponderosa Pine - (Douglas-Fir) / Manzanita Woodland Complex with 490 polygons covering 21.0% of the mapping area.Map accuracy was assessed only within the BRCA boundary. Primary analyses of the field data were presented and evaluated at an accuracy assessment meeting held from June 10-12, 2008. Results from a thematic accuracy assessment of 36 vegetation map classes remaining after accuracy assessment analysis indicated an estimate of 84.2% overall map accuracy (Kappa statistic = 83.4 %). Seventeen 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 park managers. These map classes are described in the Accuracy Assessment section of this report, as is the justification for retention.

Vegetation classification and mapping project report, Bryce Canyon National Park [and associated files]

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