Spatial Vegetation Data for Arches National Park Vegetation Mapping Project

This polygon feature class represents vegetation communities mapped at Arches National Park to an alliance or association level, depending on the photo signature. The polygons were generated using guidelines set by the Standardized National Vegetation Classification System (October 1995). Original lines were drawn on mylar overlays using the DOQs collected in June of 2002. Hard copy 9x9 photography was used for photo interpretation. Traditional image interpretation cues were used to develop the polygons, such as shape, size, pattern, tone, texture, color, and shadow. Additional data layers were used in aiding the interpretation, such as slope, hydrology, soils, geography, and ground-collected vegetation information. The minimum mapping unit was 1/2 hectare. The lines developed in the image interpretation step were scanned using a large format scanner. The resultant scanned image was converted into line work for use within ArcGIS. The line work was cleaned, polygons created and attributed. The attributed vegetation classes were subjected to an accuracy assessment, following which final adjustments were made to the vegetation classes. As with any digital layer, this layer is a representation of what is actually occurring on the ground. Errors are inherent in any interpretation of ground qualities. Due to the "snapshot" nature of the DOQs, this vegetation layer reflects conditions that existed when the imagery was collected.