Optimizing woody fuel treatments to reduce wildfire risk to sagebrush ecosystems in the Great Basin of the western US

Abstract

The sagebrush biome in the western United States is a focus of widespread conservation concern due to multiple interacting threats including larger, more severe wildfires. Given the immense scale of the region and limited resources, prioritizing restoration treatments is essential for optimizing risk reduction and managing for resilient ecosystems. We leveraged work identifying sagebrush areas suitable for woody fuel treatments based on resilience to disturbance and resistance to annual grass invasion (R&R) and areas of sagebrush mapped as high conservation value. We used wildfire simulation modeling to estimate annual wildfire exposure (area burned), and identify areas where fire is transmitted to locations of high conservation value that are low R&R. We then optimized treatment location with the ForSys spatial planning system to prioritize treatment of wildfire exposure where treatments are ecologically suitable and explored how operational restrictions (e.g., distance to roads) limited the capacity to treat exposure. Overall, woody fuel treatments could be realistically implemented in only 7.6 % (2.5 million ha) of sagebrush dominated areas. We found that 24 % of the wildfire exposure across all sagebrush associations occurred where fuel treatments were ecologically suitable, but consideration of operational constraints reduced treatable exposure to 9 %. However, there was double the opportunity to reduce transmitted exposure to areas of high conservation value in the operational scenario despite restrictions. Leveraging treatment suitability and sagebrush conservation to strategically design implementable project treatment can help direct limited resources where they are likely to have the greatest ecological and risk reduction benefit.

Keywords: Conservation investment; Decision support system; Ecological resilience; ForSys; Resistance to invasion; Restoration planning; Sagebrush ecological integrity.