Resolving Critical Issues for the Development of Ecological Site Descriptions: Summary of a Symposium

Nevada. The speakers, their affi liations, and topics are listed in the sidebar. Two important concepts emerged from the presentations and discussions. First, the ecological concepts and assumptions that underlie the development and implementation of ESDs are undergoing revision at a rapid pace. Most importantly, the assumption that reconstructing the ecological dynamics of a group of similar soil–vegetation occurrences as the basis for predicting future dynamics may be fatally fl awed in light of a relatively rapid changing climate (Archer). As our understanding of both directional climate change and spatiotemporal variability (Bestelmeyer) improves, The concepts, methods, and procedures for describing rangelands help defi ne the profession of range management. None of these is more important than the system for dividing rangelands into spatially distinct units for the purpose of classifying and managing. Range sites and range condition and the ecological concepts on which they were based dominated research, policy, and application virtually from the time SRM was formed (1948) until the late 1990s. In 1997, the revised version of the Natural Resources Conservation Service (NRCS) “National Range and Pasture Handbook” fi rst referred to Ecological Site Descriptions (ESDs) and gave basic guidance on defi nitions and procedures for implementation. The change from range sites to ecological sites is representative of two important changes in the profession: the incorporation of nonequilibrium ecology to describe rangeland dynamics in some ecosystems, and the expansion of the array of ecosystem services provided by all rangelands. In the 10 yr since, ESDs have been developed and implemented across a wide variety of ecosystems using an array of assumptions and procedures. In 2005, the Bureau of Land Management (BLM), Forest Service (FS), and NRCS signed an interagency memorandum to collaborate and adopt ESDs as a standard for the description of rangelands. This multiagency agreement represents a substantial step forward in the application of a common terminology and an approach as a basis for land management decisions. However, this agreement represents primarily administrative progress. This administrative progress must be accompanied by scientifi c advancement. To review the progress to date, and to identify the impending challenges, we organized a symposium at the 2007 Annual SRM meeting in Reno, Speakers at the symposium and the topics covered