Sacaton riparian grasslands of the Sky Islands: Mapping distribution and ecological condition using state-and-transition models in Upper Cienega Creek Watershed

Abstract

Riparian grasslands dominated by Sporobolus wrightii (big sacaton) were once widely distributed in the intermountain basins of the Madrean Archipelago. These alluvial grasslands are still recognized as key resources for watershed function, livestock, and wildlife. The upper Cienega Creek watershed in SE Arizona is thought to harbor some of the region’s most extensive sacaton stands. Documenting their extent and ecological state is important for informing management in this valley and for contributing to a clearer picture of this community’s status across the region. Our objectives were to map the distribution of sacaton; qualitatively assess stands of sacaton into ecological states; and test mapping and assessment methods for use in other valley bottoms in the region. We used a two-step approach: interpretation of aerial photography and soil maps followed by field reconnaissance. Field work consisted of qualitative, rapid assessments of ecological state using the Natural Resource Conservation Service’s State-and-Transition (S&T) models for the Loamy Bottom Ecological Site. The most open and productive state of Sacaton Grassland occupies 54 percent of alluvial habitats evaluated, with remaining acreage in various states of degradation, recovery, or transition to Mesquite Bosque woodland. Our observations in the Cienega Creek watershed suggest potential modifications to the S&T models that may more accurately reflect site potential, likelihood of transitioning to other states, and management strategies tailored to maintaining or improving sacaton grassland conditions across the region.

Parent Publication

• Merging science and management in a rapidly changing world: Biodiversity and management of the Madrean Archipelago III and 7th Conference on Research and Resource Management in the Southwestern Deserts; 2012 May 1-5; Tucson, AZ

Citation

Tiller, Ron; Hughes, Melissa; Bodner, Gita. 2013. Sacaton riparian grasslands of the Sky Islands: Mapping distribution and ecological condition using state-and-transition models in Upper Cienega Creek Watershed. In: Gottfried, Gerald J.; Ffolliott, Peter F.; Gebow, Brooke S.; Eskew, Lane G.; Collins, Loa C. Merging science and management in a rapidly changing world: Biodiversity and management of the Madrean Archipelago III and 7th Conference on Research and Resource Management in the Southwestern Deserts; 2012 May 1-5; Tucson, AZ. Proceedings. RMRS-P-67. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p. 410-424.