The Spence/Romme/Floyd-Hana/Rowlands (SRFR) Classification [version 2.0]
Spence JR. 1997. The Spence/Romme/Floyd-Hana/Rowlands (SRFR) Classification [version 2.0]. Version 2. Resource Management Division. Glen Canyon NRA
This paper outlines a hierarchical classification developed for vegetation, and includes a detailed preliminary classification of Colorado Plateau vegetation to the series level. "This listing highlights the many gaps in our knowledge of the vegetation on the Colorado Plateau. In particular, high elevation treeless vegetation and wetlands are poorly understood." The present version includes an added level "to reflect dominant plant species response to climate and soil moisture through leaf duration and life form...." The paper defines major categories, and also provides a short preliminary classification of the Sonoran-Mojave region.