How Big Blazes Shape Landscapes

During catastrophic fires like California’s Rim Fire in 2013, thousands of acres of trees can be reduced to ash and embers, says fire scientist Scott Stephens, and it’s unclear whether forests can regenerate on those huge swaths of land. Instead, quick-colonizing bushes are often first to return, claiming the open real estate as their own. In areas of Southern California, he says, some forests have transitioned to chaparral, and when the chaparral went up in flames, it gave way to grasslands full of invasives.

But smarter fire management might avoid that shift in vegetation, Stephens says, if we’re able to encourage more regular, low-level fires to blaze their way through forests. Yosemite National Park has had some success letting natural wildfires burn themselves out. And in some cases, says hydrologist Sally Thompson, burned forests there have transitioned instead to soggy wetland—a sign that smart fire management might also have collateral benefits, like increasing the water budget in the Sierra Nevada mountains.