A review of fuel treatment effects on fuels, fire behavior, and ecological resilience in sagebrush ecosystems
Sagebrush ecosystems are experiencing increases in wildfire extent and severity. Most research on vegetation treatments that reduce fuels and fire risk has been short-term (around 2-3 years) and focused on ecological responses. Researchers reviewed the causes of altered fire regimes and summarized literature on the longer-term effects of treatments that modify shrub fuels, pinyon and juniper canopy fuels, and fine herbaceous fuels. They described treatment effects on fuels, fire behavior, ecological resilience, and resistance to invasive annual grasses.
Researchers found tradeoffs in woody fuel treatments between reducing canopy fuels vs. increasing understory herbaceous vegetation (fuels) and fire behavior. In pinyon-juniper expansion areas, all treatments decreased crown fire risk. Prescribed fire and cut and broadcast burn treatments reduced woody fuels long-term but had higher risk of invasion. Mechanical treatments left understory vegetation intact and increased native perennial plants. However, cut and leave treatments increased downed woody fuel and high intensity wildfire risk, while cut and pile burn and mastication caused localized disturbances and annual grass invasion.
Ecological outcomes also depended on ecological resilience. Sites with warm and dry conditions or depleted perennial native herbaceous species experienced lower recovery and resistance to invasive annual grasses. In invasive annual grass dominated areas, high intensity targeted grazing reduced fine fuels but required retreatment or seeding. In intact ecosystems with relatively low shrub cover, dormant season targeted grazing reduced fine fuel and fire spread. Preemergent herbicides also reduced annual grasses with differing effects in warm and dry vs. cool and moist environments.
Primary considerations are the short and long-term effects on fuels and fire behavior, fire severity, and the ecological response to these targeted treatments. To increase ecological resilience and resistance to nonnative annuals, treatments should be selected that minimize fire severity and the loss of desirable perennial species in subsequent wildfires. More research is needed to prioritize areas for management and determine optimal strategies across large sagebrush landscapes.
In 2024, the agency, partners, communities, and Tribes removed more than 4.2 million acres of flammable vegetation, including 2.2 million acres of planned fires, the most of any previous year.