Browsing Rangeland Ecology & Management, Volume 61, Number 3 (May 2008) by Authors
Broad-Scale Assessment of Rangeland Health, Grand Staircase-Escalante National Monument, USAMiller, Mark E. (Society for Range Management, 2008-05-01)Over a 3-yr period, the qualitative assessment protocol ‘‘Interpreting Indicators of Rangeland Health’’ was used to evaluate the status of three ecosystem attributes (soil/site stability, hydrologic function, and biotic integrity) at over 500 locations in and adjacent to Grand Staircase-Escalante National Monument (Utah). Objectives were to provide data and interpretations to support the development of site-specific management strategies and to investigate broad-scale patterns in the status of different rangeland ecological sites. Quantitative data on ground cover, plant community composition, and soil stability were collected to aid the evaluation of qualitative attributes and improve consistency of the assessment process. Ecological sites with potential vegetation dominated by varieties of big sagebrush (Artemisia tridentata Nuttall) had the highest frequencies (46.7%-75.0%) of assessments with low ratings (moderate or greater departure from expected reference conditions) for all three ecosystem attributes. In contrast, sites with potential vegetation characterized by Utah juniper ( Juniperus osteosperma [Torrey] Little) and/ or Colorado pinyon (Pinus edulis Engelmann) had low frequencies (0.0%-7.8%) of assessments with low ratings for all attributes. Several interacting factors likely contributed to the development of patterns among ecological sites, including 1) potential primary production and thus long-term exposure to production-oriented land uses such as livestock grazing; 2) the presence of unpalatable woody plants capable of increasing and becoming persistent site dominants due to selective herbivory, absence of fire, or succession; 3) soil texture through effects on hydrologic responses to livestock grazing, trampling, and other disturbances; and 4) past management that resulted in high livestock use of ecological sites with sensitive fine-loamy soils following treatments designed to increase forage availability. This case study illustrates an extensive application of an assessment technique that is receiving increasing use worldwide, and results contribute to an understanding of factors contributing to patterns and processes of rangeland degradation.