The US National Vegetation Classification (NVC) offers the nation a consistent hierarchical solution for the classification of existing vegetation. With the adoption of the NVC by natural resource organizations, efforts are under way to cross-reference legacy classifications and to integrate the NVC with other data themes to facilitate business needs. The Southwestern Region of the US Forest Service employs an ecosystem type framework of Ecological Response Units (ERUs) to stratify landscapes for purposes of analysis, planning, management, and research. The ERUs are similar in concept to LANDFIRE Biophysical Settings, but are coarser thematically, tailored for management purposes, aligned with regional data and conventions, and reflect more recent classification concepts. The ERU units were developed through multivariate analysis and interpretation of available classification summaries, and then mapped through the compilation and normalization of multiple map sources. Integrating NVC and ERU mapping allows for consistent analysis of current vegetation conditions for major ecosystem types.
By cross-referencing available existing vegetation mapping and classification at the NVC Group level, and by integrating this information with ERUs both thematically and spatially, we were able to: 1) generate a map for the majority of NVC Groups for Arizona and New Mexico; 2) determine the many-to-one relationships of NVC Groups to ERUs; 3) identify classification issues with NVC Groups; and 4) provide an initial working NVC-ERU framework. For NVC Group mapping the availability of spatial information necessitated the combination of some Groups into more general map units that still retain greater thematic detail then the next upper NVC level of Macrogroups. The resulting NVC map and NVC-ERU framework can support some business needs of regional land managers. The NVC-ERU framework presents an opportunity for more consistent application of mapping and classification among natural resource organizations and for greater exchange of data, analyses, and reporting.