The Ecological Site Concept classifies land based on the ability of recurring soil, physiographic, geological, and climatic variables to produce distinctive vegetation communities and to have a similar pattern of response to disturbance and management actions. Ecological Site Descriptions (ESDs) are interagency-developed documents that describe vegetation potential and the natural range of variation in these variables within an Ecological Site. Two components of ESDs frequently used by the Bureau of Land Management (BLM) are the state-and-transition model (STM) and the Interpreting Indicators of Rangeland Health (IIRH) reference sheet. STMs are conceptual schematics of plant community dynamics in response to disturbances, land uses, and biological processes. IIRH is an ecological assessment protocol that evaluates soil/site stability, hydrologic function, and biotic integrity by rating observed departures of a suite of seventeen qualitative indicators from conditions documented in a reference sheet, and reflective of the natural range of variability for an ecological site. Assessment, Inventory, and Monitoring (AIM) is a BLM monitoring protocol implemented throughout the agency’s jurisdiction that provides research-grade vegetation and soil data to guide agency management decisions across spatial scales, ranging from local field offices to all BLM lands nationwide. The Idaho BLM is reviewing priority ESDs to better understand site potential and management responses for seven ecological sites, representing the majority of designated greater sage-grouse (Centrocercus urophasianus) habitat in Idaho. We are using a six-step multivariate analysis of AIM data on the priority ESDs to develop empirically-derived STMs with quantitative estimates of plant species cover and drivers of transitions. Additionally, we are developing an STM with estimates of cover by functional/structural group to more closely align with the IIRH indicators of biotic integrity. Finally, we extract empirical descriptions and appropriate quantitative estimates of the seventeen IIRH indicators from AIM monitoring plot data and field notes representing the reference state of an ecological site described in its newly derived STM. Improved STMs and reference sheets in ESDs will allow for more effective implementation of the IIRH protocol.
Results/Conclusions
This presentation will unveil the new STM and reference sheet for Ecological Site R025XY019ID, a loamy sagebrush steppe ecological site at the nexus of the western Snake River Plain and northern Owyhee Plateau and highlight new features tailored to improve the IIRH assessments and future management decisions.