A sagebrush conservation design to proactively restore America’s sagebrush biome

Abstract

A working group of experts with diverse backgrounds and disciplinary expertise was assembled to conceptualize a spatially explicit conservation design to support and inform the Sagebrush Conservation Strategy Part 2. The goal was to leverage recent advancements in remotely sensed landcover products to develop spatially and temporally explicit maps of sagebrush rangeland condition and landscape threats. In addition, the group sought to provide a common basis for understanding the state of sagebrush rangelands through time. First, the study team developed a spatially explicit model to assess geographic patterns in sagebrush ecological integrity and used this model to identify core sagebrush areas (CSAs), growth opportunity areas (GOAs), and other rangeland areas (ORAs) across the biome. Among the identified rangelands, 13.6 percent were classified as CSAs; 34.4 percent, as GOAs; and 51.9 percent, as ORAs. This equated to 33.4 million acres of CSAs and 84.3 million acres of GOAs, or 117.7 million acres of CSAs and GOAs combined as of 2020. Second, the team sought to demonstrate the ecological relevance Agriculture of the identified CSAs and GOAs by comparing these data with independent datasets for sagebrush obligate species of conservation concern. Geographical patterns in sagebrush ecological integrity were strongly associated with high-priority species and displayed clear links to population performance for Centrocercus urophasianus (Bonaparte, 1827) (greater sage-grouse). The positive link to greater sage-grouse population trends in CSAs is important, as habitat management designations for this species have largely driven conservation actions across the sagebrush biome for the past several decades. Third, the team parsed out the type, location, and acres of primary threats within the different categories (CSAs, GOAs, and ORAs) to help focus active management by identifying places where multiagency and organization efforts can protect CSAs and GOAs that have higher levels of integrity with lower cumulative threats. The assessment of the condition of the sagebrush biome (that is, the location, amount, and conservation status) indicated that complex ecosystem function problems are driving ~73 percent of the demonstrated threats within the CSAs and GOAs (rather than point-source problems, such as human development). Fourth, the team developed trend estimates for the identified CSAs and GOAs and three selected primary threats (invasive annual grasses, conifer encroachment, and human modification) to the sagebrush biome from 2001 to 2020. Results showed that an average of 1.3 million acres per year have transitioned to ORAs at an annual rate of -1.34 percent. Fifth, the team developed an approach to integrate climate change effects into the threat-based landscape conservation design and conducted an initial assessment on the magnitude of near-term climate effects in the context of observed historical trends. The team’s analysis suggests that climate change alone is unlikely to be the dominant threat to sagebrush ecological integrity in the next few decades, although interactions of climate with wildfire and invasive annual grasses may be an important threat, especially in the longer term.

Citation

Doherty, Kevin; Theobald, David M.; Bradford, John B.; Wiechman, Lief A.; Bedrosian, Geoffrey; Boyd, Chad S.; Cahill, Matthew; Coates, Peter S.; Creutzburg, Megan K.; Crist, Michele R.; Finn, Sean P.; Kumar, Alexander V.; Littlefield, Caitlin E.; Maestas, Jeremy D.; Prentice, Karen L.; Prochazka, Brian G.; Remington, Thomas E.; Sparklin, William D.; Tull, John C.; Wurtzebach, Zachary; Zeller, Katherine A. 2022. A sagebrush conservation design to proactively restore America’s sagebrush biome. Open-File Report 2022-1081. Reston, VA: U.S. Geological Survey. 38 p.