Vegetation Classification and Mapping Project Report, Hovenweep National Monument

Von Loh, Jim; Wakefield, Gery; Wight, Aneth; Evenden, Angie; Coles, Janet

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 Hovenweep National Monument (HOVE). This collaborative effort involved many project partners, particularly engineering-environmental Management, Inc. (e2M), the Western Region office of NatureServe, and their cooperators. The mapping area is 326 hectares (805 acres), encompassing the six management units of the Monument. Mapping extended only to the boundaries of each HOVE unit. Ecologists, botanists, and photointerpreters worked together to identify plant associations for HOVE and determine how best to map them using 1:12,000-scale color aerial photography. The team collected vegetation and environmental data from 27 vegetation classification plots and 32 observation points. No supplemental fuels data were collected during the project. Fieldwork and mapping were completed between 2003 and 2007.Analysis of the plot data revealed 29 National Vegetation Classification plant associations or park special vegetation types within the Monument. An additional five vegetation associations and alliances were documented in field notes and formed the basis of map classes, but were not sampled.Vegetation and land use were interpreted to the most detailed level possible using high resolution, 1:12,000-scale color aerial photography that had been digitally scanned andorthorectified. Most of the interpretation was based on site visit information, because virtually every part of the Monument is accessible on foot. Polygons representing vegetation or land use map classes were delineated on the stereo photographs and transferred to a spatial database. Because the individual Monument parcels are so small, the standard minimum mapping unit of 0.5 ha was discarded and polygons were delineated to approximately 0.1 ha (0.3 acres).A total of 338 map polygons representing 29 natural and semi-natural vegetation map classes were developed for the HOVE mapping project. Two geologic map classes describe 57 additional polygons and two land use map classes describe 13 polygons. Average polygon size across all map classes is 0.8 ha (2.0 acres). The most frequent vegetation mapping unit is Wyoming Sagebrush Disturbed Shrubland (Map Class # 23) with 54 polygons covering 77.6 ha (24%) of the mapped area.Because each polygon was visited and delineated in the field, we chose not to conduct a thematic accuracy assessment of the vegetated map classes. A thorough field verification of map polygons was employed instead. Results of this verification trip are available in a separate report.

Vegetation Classification and Mapping Project Report, Hovenweep National Monument

Series

Collections