Environment & Science

What will the Thomas Fire burn zone look like in the future?

Wildflowers surround burnt trees near Interstate 15 in Fallbrook, California, in a landscape that burned in the 2007 Rice Fire when wildfires of historic size and intensity swept across Southern California.
Wildflowers surround burnt trees near Interstate 15 in Fallbrook, California, in a landscape that burned in the 2007 Rice Fire when wildfires of historic size and intensity swept across Southern California.
David McNew/Getty Images

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What will the massive area burned by the Thomas Fire look like in the future? Scientists say it depends on two things: how much it rains, and how soon another wildfire sweeps through.

Right now, much of the countryside in rural Ventura and Santa Barbara Counties is scorched. The soil is gray, tree trunks are black and rocks are covered in a film of white ash.

But if the area receives close to a normal amount of rain this winter — approximately 17 inches — wildflowers will cover the hillsides this spring.

Wildflowers bloom among trees that burned in the 2007 Poomacha Fire on the Rincon Indian Reservation in northern San Diego County.
Wildflowers bloom among trees that burned in the 2007 Poomacha Fire on the Rincon Indian Reservation in northern San Diego County.
David McNew/Getty Images

These aren’t any old wildflowers. These are "fire endemics," flowers that only bloom after wildfires. Their seeds need to be exposed to heat or smoke — yes, smoke! — to germinate. 

"It's wonderful!” said an audibly excited Richard Halsey, the director of the Chaparral Institute. “What happens is, the landscape stays black but you see tufts of green and there’s an explosion of wildflowers. It creates a colorful carpet, which people have never seen.”

Wildflowers bloom among trees that burned in the Poomacha Fire on the Rincon Indian Reservation in northern San Diego County.
Wildflowers bloom among trees that burned in the Poomacha Fire on the Rincon Indian Reservation in northern San Diego County.
David McNew/Getty Images

Within the next few weeks, shrubs like toyon and greasewood will begin sprouting new leaves from their charred stumps – an adaption to the high-severity fires that sweep through Southern California’s Mediterranean landscapes that is unusual in other ecosystems, according to Jon Keeley, a research scientist with the U.S. Geological Survey who specializes in shrublands.

New leaves sprout from the base of a burned chamise, or greasewood, shrub after a wildfire.
New leaves sprout from the base of a burned chamise, or greasewood, shrub after a wildfire.
Courtesy of Jon Keeley

But if it is a dry winter, many of these new seedlings won’t survive. And without healthy adult chaparral on the landscape, fast-growing invasive grasses will soon move into to take their place, said Max Moritz, who studies wildfires at UC Cooperative Extension in Santa Barbara. 

If Thomas Fire's burn zone is scorched by another wildfire again in the near future, that can also lessen the chance of the ecosystem recovering. Chaparral shrubs like manzanita, California lilacs, greasewood, and scrub oak can take up to 20 years to grow to adulthood and drop enough seeds so that if a wildfire does burn through, there is a “seedbank” in place to re-generate the ecosystem.

If fires come too frequently and burn shrubs before they’ve reached maturity, the seedbank will slowly disappear over time. This also leads to the invasion of an area by non-native grasses, which become like kindling when they dry out in the summer and fall, increasing the likelihood that fires will burn more frequently.