Final Report: Improving the Success of Post-Fire Adaptive Management Strategies in Sagebrush Steppe
Dates
Publication Date
2021-04-16
Citation
Matthew Germino, 2021-04-16, Final Report: Improving the Success of Post-Fire Adaptive Management Strategies in Sagebrush Steppe: .
Summary
Identifying the weather thresholds that can transform plant communities is key to assessing the vulnerability of ecosystems to drought and climate shifts, and thus enabling adaptive management to mitigate their impacts on land resources. We asked whether and how drought contributes to decline of big sagebrush, a widespread shrub of the western US that is critical for wildlife such as the imperiled sage grouse yet is poorly adapted to fire. Our objective was to quantitatively define “ecological drought” – water deficits that result in impacts to ecosystems - based on a precise set of weather and soil moisture conditions that are associated with failure of sagebrush stands to recover and sites converted into low-diversity grasslands [...]
Summary
Identifying the weather thresholds that can transform plant communities is key to assessing the vulnerability of ecosystems to drought and climate shifts, and thus enabling adaptive management to mitigate their impacts on land resources. We asked whether and how drought contributes to decline of big sagebrush, a widespread shrub of the western US that is critical for wildlife such as the imperiled sage grouse yet is poorly adapted to fire. Our objective was to quantitatively define “ecological drought” – water deficits that result in impacts to ecosystems - based on a precise set of weather and soil moisture conditions that are associated with failure of sagebrush stands to recover and sites converted into low-diversity grasslands prone to re-burning. Using state-of-the art downscaled weather, soil-water modeling, and robust field or remotely sensed data on sagebrush abundances for hundreds of burned and re-seeded areas over a ~25 year period, we discovered that weather conditions are indeed associated with success or failure of post-fire sagebrush seeding. Specifically, failed seedings had a week less of readily available water in the top layer of soil during March of the year after post-fire seeding, compared to sites where sagebrush recovered. However, convenient and readily available (but coarse) drought indices such as the Standardized Precipitation-Evaporation Index (SPEI) were not able to predict the changes in sagebrush abundance. These results are significant considering that post-fire seeding of sagebrush is one of the largest restoration activities occurring on earth, yet recovery rates have historically been low. Our results help explain why seeding successes and failures may have occurred in the past and can be used to help plan when and where seedings may be more successful in the future. The findings were used in creating a drought-module tool that help managers determine the historical and future threat of drought for particular areas of restoration interest within the USGS/BLM Land Treatment Exploration Tool that is now used routinely across the Department of Interior for planning post-fire management.
