Terrestrial Ecological Unit Inventory on Two Southwestern Forests: Adapting Digital Mapping Methods to Fit the Landscape

The USDA Forest Service Southwestern Region Terrestrial Ecological Unit Inventory (TEUI) is a systematic and integrated approach to mapping climate, soil and vegetation along an environmental gradient A terrestrial ecological unit consists of one or more soil family phases, potential natural vegetation, and the unique climatic and geomorphic setting in which it occurs.

TEUI methods in the southwestern region are shifting to predominantly digital mapping methods using Geographic Information System technology and the TEUI Geospatial Toolkit (hereinafter referred to as the Toolkit). The Toolkit is a resource-mapping application designed to assist the USDA Forest Service in conducting TEUI by providing the enhanced ability to visualize, delineate, and analyze landscapes using geospatial data. The TEUI teams working on the Gila and Tonto National Forests have found that an approach that uses the Toolkit in the office, and both aerial photos and Toolkit-generated maps in the field takes advantage of the versatility and efficiency of spatial data and the three-dimensional visualization of aerial photography. Prior to field mapping, inventory teams use the Toolkit to obtain remotely sensed and other spatial data that is used for visualization, work planning, and pre-mapping image segmentation. In the field, printed field maps with the preliminary segmentation are used along with aerial photos to navigate and to direct and focus sampling efforts. After extensive field sampling is complete, the teams use the Toolkit to compute and analyze statistics on the map unit polygons to evaluate geospatial variability within and between polygons and assess consistency of ecological unit concepts and detect potential errors. Ecological unit polygons are then edited and finalized using the Toolkit.

Due to landscape variation and complexity between the Gila and Tonto National Forests, each team has adapted these methods to best address the unique challenges of their mapping areas.