Vegetation Classification and Distribution Mapping Report: Petrified Forest National Park

Thomas, Kathryn; Cully, Anne; Hutchinson, J.M.; McTeague, Monica; Schulz, Keith

The classification and distribution mapping of the vegetation of Petrified Forest National Park (PEFO) and surrounding environment was completed through a multi-agency effort between 2003 and 2007. The project team described 39 plant communities for PEFO; 38 of which were described from quantitative classification of based on field-relevé data collected in 1996 and 2003. The team derived one additional plant community from field observations during the photointerpretation phase of the project and field documented it during accuracy assessment. The National Vegetation Classification Standard served as a conceptual framework for assigning these plant communities to the alliance and association level. Seven of the thirty-nine plant communities were designated “park specials”; that is, plant communities with insufficient data to describe them as new alliances or associations.The project team also developed a spatial vegetation map database representing PEFO, with four different map-class schemas: base, group, macrogroup, and management map classes. The base map classes represented the finest level of spatial detail. Initial polygons were through manual interpretation of 2003/2004 1:6,000 true color aerial photography supplemented by occassional computer screen digitizing on a mosaic of digitized aerial photos. These polygons were labeled with base map classes during photointerpretation. Field visits verified interpretation concepts. The vegetation map database includes 1) 46 base map classes, which consist of associations and park specials classified with the quantitative analysis, 2) one additional association noted during photointerpretation, and 3) non-vegetated land cover, such as infrastructure, land use, and geological land. The base map classes consist of 6,989 polygons in the project area. A field-based accuracy assessment of the base map classes showed the overall accuracy to be 40.6% cover. The group map classes represent aggregations of the base map classes, approximating the group level of the National Vegetation Classification Standard (NVCS), version 2 (Federal Geographic Data Committee 2008). Terrestrial ecological systems, as described by NatureServe (Comer et al. 2003), were used as a first approximation of the group level. The project team identified 15 group map classes for this project. The overall accuracy of the group map classes was determined using the same accuracy assessment data as for the base map classes. The overall accuracy of the group representation of vegetation was 55.7%. The next higher level of the NVCS, the macrogroup, was also used to develop a map class schema. The project team identified 13 macrogroup map classes. The overall accuracy of the macro group representation of vegetation was 73.5%. In consultation with park staff, the team developed management map classes, consisting of park-defined groupings of base map classes intended to represent a balance between maintaining required accuracy and providing a focus on vegetation of particular interest or import to park managers. The 24 management map classes had an overall accuracy of 68.6%.

Vegetation Classification and Distribution Mapping Report: Petrified Forest National Park

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