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n response to massive wildfires, federal agencies often sow large quantities of native and non-native seed mixes across thousands of acres of burned land in the hope that reseeding will help perennial, more fire-resistant grasses outcompete exotic and invasive annuals like cheatgrass and ventenata. The forest service and state agencies have been experimenting with aerial and ground-based mulching to arrest erosion on burned slopes. And private landowners are increasingly using post-fire seeding, planting, mulching and other treatments to protect roads, streams, buildings and other landscape and property values from debris flows and flooding. What are the impacts of these treatments on the future health, diversity and resilience of the landscape? What are researchers learning about post-fire treatments that can guide our hands after the next big burn?

Fortunately, research taking place across the West is increasingly seeking answers to these complex questions. Recent research out of the Great Basin region highlighted in Ecosphere and Restoration Ecology examines the impacts of changing fire regimes and the genetic consequences of post-fire restoration treatments like seeding. 

Researchers found that while, “across vegetation types, wildfires were larger and more frequent in the contemporary period (1991–2020) than in the recent past (1961–1990),” the shifts were largely associated with invasive annual grasses and human ignitions. That suggests to the authors that proactive invasive species control, including in post-fire recovery efforts, and “more targeted education and prevention efforts,” could protect resource and human values. In other words, the problem is not out of our control. That’s more comforting than the alternative.

Genetic diversity is important because it is the source of a species’ ability to adapt to environmental changes.

More good news emerges on the invasive annual grasses front when you consider the second paper, which looked at the impacts on genetic diversity of native species after post-fire reseeding projects in Oregon. Genetic diversity is important because it is the source of a species’ ability to adapt to environmental changes. The question is whether the commercially produced native seeds that are used to revegetate burned areas after large wildfires are compromising the genetic diversity of the native vegetation. Researchers found the answer was a resounding “No.” The study found similar genetic diversity between seeded and non-seeded areas four and five years post-fire. Several other studies cited by the authors have found that re-seeding native perennial bunchgrasses post-fire is key to interrupting the “increasingly problematic cycle of wildfire promoted by exotic annual grasses (EAGs) and displacement of perennials by post-fire increases in EAGs.” 

In short, post-fire re-seeding of native perennials in the sagebrush steppe is critical, and doesn’t have negative effects on the gene pool.