Two years ago, the Woolsey Fire burned nearly 97,000 acres—neighborhoods, businesses, bridges, highways and, of course, the mountains. Tens of thousands of acres of mountains.
The fire burned shrubs, succulents, frog breeding habitat and mountain lion territory. It burned invasive species and natives alike, and visitor centers and untrod wilderness alike. In total, it burned 87 percent of national park land in the mountains.
Now, two years later, Santa Monica Mountains National Recreation Area (SMMNRA) biologist Mark Mendelsohn says the signs of the fire are still front-and-center.
Black, twisted “shrub skeletons” would be visible for more than a decade, Mendelsohn said, and regrown shrub height continues to be lower than it was before the fire, although it is growing. But one of the most noticeable changes is the density of dead mustard, an invasive weedthat sprouts up after a fire. After the rainy winter of 2018-19, the Santa Monica Mountains saw a remarkable growth of mustard, SMMNRA restoration ecologist Joey Algiers described, a tall, yellow-flowered plant “capitalizing” on the burned areas and taking root before slower-growing native species had a chance to germinate. Now, those acres of mustard are dry, dead stalks that are much less fire resistant than native shrubs and other flora.
“They suppress native species from recovering,” Algiers explained. “They make it difficult for native species, which germinate later and grow slower. Invasive species can get a foothold in new areas, so it’s our job to go in there and control them and allow the native vegetation to recover naturally.”
Algiers leads a team, often including local volunteers, pulling weeds by hand and planting native species (26,000 plants in the current restoration project) in the hopes of claiming back areas of the mountains that are being choked by around 300 nonnative species (of which about 100 are considered invasive). His focus, specifically, is on “the top 25 we consider to be the most ecologically damaging,” the ecologist described, later referring to the list as “the evil 25.”
And, despite the fire wiping out so much park land, treatments seem to be working.
“Areas we treated before the fire, that we have good treatment history on, showed really good results after the fire,” Algiers said, “meaning they didn’t rebound to what they were before ... Where, a stone’s throw away, areas that weren’t treated were covered in invasive species. That’s promising—it shows the work we were doing before the fire mitigates against these big wildfires.”
And, Algiers said, native “fire-followers” appeared all over the mountains after the fire: “amazing blooms” of native wildflower species and herbs. “The process takes a while. The first ones that come in are the wildflowers—the fire followers—and the shrubs will eventually close the canopy,” and will remain until they burn and resprout again—it could be decades—”50, 60, even 100 years”—before that cycle repeats. “Many of them are [annuals and] it will serve as a cue for them to come up, if you get rainfall [after a fire],” Algiers said. “Then you’ll see the beautiful blooms again, and then maybe not for the rest of your life.”
According to Mendelsohn, some native plants that seemed to have fared the worst in the fire are also showing signs of regrowth, although they are not out of the weeds yet.
One type of succulent, the dudleya (sometimes called “live-forevers”)—with several subspecies that live only in the Santa Monica Mountains—is staging a comeback despite the odds.
“A few of them, almost all of their populations were burned in the Woolsey Fire,” Mendelsohn said, but his team is closely tracking the recovery of this “cute little plant,” the botanist continued, as well as the lichen out of which it grows.
As for animals, the SMMNRA was five years into an introduction project for the California red-legged frog when the fire struck.
“The project was going great. We had breeding success in two of the five reintroduction spots and we were hopeful the following spring we would have breeding in the remaining spots, but the fire really set back the success of the project,” Mendelsohn said. “Luckily—fortunately—we still do have adult frogs in all of our reintroduction places, so a number of individuals did survive the fire,” but only one site has seen the frogs breeding. Because of the fire and hillside erosion afterward, mud and sediment clog the deep pools the frogs need to breed. But in time, “hopefully, the streams will be washed out by storms and return the breeding habitat.”
The lasting effect of Woolsey resulted in a mountain ecosystem that will never be exactly what it was, Mendelsohn said, but the ecosystem “did evolve to recover from fire.”
“In time, without additional fire and other disturbance and, hopefully, with controlling of weeds, plants will return to about what they looked like, and we don’t know at this point of the loss of any animals that won’t return,” the botanist said, adding, “It’s really all about the plants recovering—it really is—so, as the plants recover, we do expect things to kind of return to the way they were.”
When asked about prescribed burns in the mountains, Algiers said that the issue is not that the mountains do not burn often enough—as may be the case in Northern California—but, rather, that they burn far too often to support native species’ growth.
“It takes a while for our native shrubs to recover,” Algiers said.
“Prescribed burn is a valuable tool in some systems, but that isn’t the case in the Santa Monica Mountains,” he added. “We don’t need prescribed fires. We have too many fires—we need fewer fires.”
Editor's note: The story was updated to clarify that mustard is a weed, not a grass, and to correct a quote from Joey Algiers.