Vegetation Classification, Distribution,and Mapping Report Casa Grande Ruins National Monument

Buckley, Steve; Drake, Same; Greene, Jon; Villarreal, Miquel; Hubbard, Andrew; Studd, Sarah

In 2007–2008, the National Park Service, Sonoran Desert Network Inventory and Monitoring Program, in cooperation with the Arizona Remote Sensing Center (University of Arizona, Offi ce of Arid Lands Studies), carried out classification and mapping of vegetation at Casa Grande Ruins National Monument (CAGR), as part of the national U.S. Geological Survey–National Park Service Vegetation Characterization Program. The primary objective of the program is to produce high-quality, standardized maps and associated data sets of vegetation and other land cover occurring within the parks (http://science. nature.nps.gov/im/inventory/veg/index.cfm). In particular, the aim of this project was to create a vegetation map at the National Vegetation Classification alliance level or finer, with a minimum mapping unit of 0.5 hectares, thematic accuracy of 80% or better per map class, and spatial accuracy meeting U.S. National Map Accuracy Standards. Project scoping was initiated in October of 2007, at a multi-park scoping meeting held at CAGR. Quick-bird satellite imagery was acquired on December 3, 2007, as a new, tasked acquisition for this project, covering both the main unit and several surrounding Arizona State Trust land parcels proposed as part of a monument expansion. The total project mapping area was 425 hectares, including a 100-m buff er zone outside monument boundaries. Image preprocessing and initial interpretation to the formation level were done at the Arizona Remote Sensing Center, University of Arizona. The draft formation-level map was produced through visual interpretation of the pan-sharpened imagery and heads-up digitizing in ArcGIS to delineate polygons. Ten formations within 44 polygons were identified, based on the percentages of tree, shrub, and herbaceous cover present. Field verification of the draft formation map and floristic data collection was conducted simultaneously during March 2008. Crews annotated boundary changes onto hard-copy maps showing imagery overlaid with draft polygons. The monument’s small size allowed for a census-style approach to each minimum mapping unit (polygons) identified. Field edits were subsequently incorporated into the digital draft formation map (shapefile) using ArcGIS. In addition to polygon scale data, 25 plots measuring 20 × 50 m were sampled across both units with an aim to sample each of the community types identifi ed. Plot and polygon data was entered into an Access database and quality checked before data analysis was conducted. In total, 42 polygons were mapped and attributed with National Vegetation Classifi cation Standard alliance-level data or land-cover classes. Urbanized environs outside the monument boundary were assigned one of seven Anderson land use classes. Full descriptions are found in Appendix A, and provide both local and regional context for each vegetation type (to the extent available at the time of this report). Map thematic accuracy was assessed within the total project area by way of a fi eld-based census. Overall thematic map accuracy for the entire effort was assessed at 96%.

Vegetation Classification, Distribution,and Mapping Report Casa Grande Ruins National Monument

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