Summer had not yet arrived, but already the hillside on the edge of Los Padres National Forest was the color of toast.

Even a brilliantly sunny day couldn’t dress up the dull palette of invasive grasses that had transformed the slope into a dried-up weed patch.

Only a sprinkling of young shrubs provided a hint of what the spot looked like before it had burned — again and again and again.

In the last 22 years, three wildfires have swept across the area, all but erasing the cover of gray-green sage scrub documented in 1930s aerial photographs.

Southern California’s native shrublands are famously tough. Conservationist John Muir celebrated them as Mother Nature at her “most ruggedly, thornily savage.”

They evolved along with long, hot summers, at least six rainless months a year and intense wildfires.

But not this much fire, this often.

The combination of too-frequent wildfires and drought amplified by climate change poses a growing threat to wildlands that deliver drinking water to millions, provide refuge from Southland sprawl and — 142 years after Muir penned his mash note — are still home to mountain lions, bears and big-eared woodrats.

The footprint of the 2003 Piru fire can be seen atop a ridge in the Lake Piru Recreation Area. After the wildfire, invasive grasses (brown) replaced native shrub growth (green). Al Seib / Los Angeles Times

Burn maps show the astonishing extent of the wildfires that have seared the southern portion of the Los Padres forest and adjacent lands.

The border of the 2007 Zaca fire bleeds into the even bigger 2017 Thomas fire, which in turn runs into the footprint of the 2006 Day fire. Together they incinerated an area roughly twice the combined size of Los Angeles and San Francisco.

Dozens of other wildfires have raced across the forest’s crumpled terrain in recent decades, including the 1997 Hopper, 2003 Piru and 2007 Ranch fires that blackened the grassy hill near Lake Piru.

“There are not that many places where there’s really old habitat left, that hasn’t seen a fire in the 30 years I’ve been here,” said Los Padres forest biologist Kevin Cooper, who retired last month.

Since 1950, hundreds of wildfires have burned in and around the southern portion of Los Padres National Forest. Sources: Cal Fire, Nextzen and OpenStreetMap

Wipe the steep mountainsides clean with flames and there is nothing to hold on to rainfall and let it seep into the ground, recharging aquifers.

There is nothing to prevent soil from washing away and silting up reservoirs and fish streams.

There is nothing to stop rivers of mud and rocks from crashing into foothill communities.

The Thomas fire was barely contained when monster debris flows roared down denuded slopes last January, killing at least 21 people and destroying more than 100 homes in the Montecito area.

There are not that many places where there’s really old habitat left, that hasn’t seen a fire in the 30 years I’ve been here. Kevin Cooper, Los Padres forest biologist

Across Southern California, oft-scorched shrublands have given way to monotonous expanses of quick-to-dry invasive grasses that are of little ecological value, don’t anchor the soil as well as deep-rooted chaparral plants and ignite easily, fueling more and more fires.

Frequent fire is driving chaparral loss in the Santa Monica Mountains, which burned yet again in November. Roughly a quarter of the 97,000-acre Woolsey fire was a reburn of land charred in wildland blazes over the last two decades.

Once gone, the chaparral and sage scrub that drape the wildest parts of Southern California are proving ominously difficult to restore.

“For so long, people thought of chaparral landscapes as being so resilient that papers came out in the ’70s on ‘How do you get rid of this stuff — it keeps growing back,’” said Nicole Molinari, the U.S. Forest Service ecologist for Southern California.

“And here we are finding ourselves at a time when we’re actually concerned about its ability to persist and trying to restore it and having challenges in doing so. That to me is a little frightening.”

Shane Dewees, left, Sameer Saroa and Stephanie Ma walk through thick invasive grasses that are crowding post-fire growth of native sage plants. Al Seib / Los Angeles Times

When scrubland turns to grass

Southern California’s native chaparral and sage scrub aren’t so much adapted to wildfire as they are to a certain pattern of fire — periodically burning in hot, intense blazes that consume all the vegetation.

Rebirth begins almost immediately. Certain species, such as toyon and scrub oak, resprout from underground root systems or burls. Within months of the Thomas fire, bouquets of bright green shoots studded the bare, ashen mountainsides lining Highway 33.

Other shrubs, such as ceanothus, regenerate when heat from the flames or chemicals from charred wood stimulate the germination of their dormant seeds.

Pictures in the News | Friday Jan. 11, 2019 »

But the spread of two things — people and non-native grasses — are helping disrupt that pattern by putting too much fire on the landscape too often.

Lightning accounts for less than a quarter of the fire starts in Southern California’s four national forests. Most ignitions are human-related.

Ranch hands repairing a pipe started the Zaca. A transient burning trash ignited the Day. Laborers doing construction work on a boat launch sparked the Piru.

Officials have not declared a cause of the Thomas blaze, which burned into the Los Padres forest from adjoining land. But Southern California Edison has said its electrical equipment probably helped start the fire, thought to have had at least two ignition points.

The prevalence of human ignitions means wildfires are more likely to erupt when sundowner and Santa Ana winds can whip them into a fury, as happened with the Woolsey and the Thomas, the state’s second-largest wildland fire on record.

Frequent big fires mean that shrublands that would naturally burn at intervals of 30 to 60 years — or even a century or more — are sometimes torched at intervals of a decade or less.

When that happens, resprouting species don’t have sufficient time to regrow. Non-sprouting shrubs can’t reach maturity and shower the ground with a new seed bank.

Invaders can then take over in a process ecologists call type conversion.

Slopes that wore a thick green jacket of wildlife-supporting shrubs turn brown under a blanket of exotic annual grasses that are dry and dead most of the year.

Native wildflowers struggle to take root in the thick mats of non-natives. Erosion increases. Biodiversity declines. The fire cycle accelerates.

“The more grass you get, the more likely you are to have fire,” said Carla D’Antonio, a professor of ecology at UC Santa Barbara. “That’s a point that a lot of people don’t appreciate.”

She is overseeing restoration research as part of a multifaceted fire recovery program in the Los Padres forest.

UC Santa Barbara ecology professor Carla D’Antonio inspects cuttings of native chaparral plants in a campus greenhouse. Researchers will plant them at restoration sites in Los Padres National Forest. Al Seib / Los Angeles Times Shane Dewees, bottom, and other researchers, top, clean native shrub seeds in a botany lab. The seeds of some chaparral plants need to be treated with heat or liquid smoke to simulate the fire conditions that would naturally trigger germination. Al Seib / Los Angeles Times Shane Dewees, right, and other researchers clean native shrub seeds in a botany lab. The seeds of some chaparral plants need to be treated with heat or liquid smoke to simulate the fire conditions that would naturally trigger germination. Al Seib / Los Angeles Times

Now in its third year, the work is painstaking and, so far, disheartening.

Students collected native shrub seeds by hand from local watersheds to maintain genetic purity. They cleaned the seeds in a campus botany lab. They soaked some in hot water to simulate the heat from a fire.

They experimented with different pre-planting methods at restoration sites near Lake Piru. Some patches were weeded, some were scraped bare. Others were left alone.

They planted more than 1,200 baby ceanothus, toyon, sage and other natives that were grown in a campus greenhouse using a special mix of potting soil and dirt from the sites.

They spread 40,000 seeds on the ground.

Stephanie Ma collects seeds from a native plant. The team uses seeds from the restoration areas to ensure genetic purity. Al Seib / Los Angeles Times

On a June afternoon in the field, UC researchers Stephanie Ma, Shane Dewees and Sameer Saroa hunted for survivors.

“This guy is kind of alive,” DeWees said, kneeling near a tiny ceanothus seedling. Ma, crawling on her hands and knees, spied another. “We have some survival here,” she reported.

But mostly they found shriveled twigs or bare dirt next to the planting flags, which doubled as little tombstones.

“Long hot days with a lot of death,” is the way Dewees described the team’s field checks. “So if you can get one little leaf, it’s not all despair.”

All told, nearly three-quarters of the infant shrubs died. The seeding was an almost total failure, producing a paltry five plants.

When the research team checked spots marked by small flags where they had planted native seedlings in 2017 and early 2018, they often found bare dirt or shriveled twigs. Al Seib / Los Angeles Times

D’Antonio suspects that rodents, accustomed to dining on an abundance of invasive grass seeds, gobbled up most of the native seeds before they could sprout.

The previous winter’s meager rainfall contributed to the seedling mortality, as did crowding by a medley of non-natives: mustard, red brome, wild oat and foxtail.

“Shrub seedlings just can’t hack competition from the grasses,” D’Antonio said.

The more grass you get, the more likely you are to have fire. That’s a point that a lot of people don’t appreciate. Carla D’Antonio, UC Santa Barbara ecology professor

Southern Californians tend to dismiss their native flora as a bunch of brush — something to be whacked and cleared and feared.

When Dewees explains his project to private landowners in the Piru area, he said some of them ask “why we’re restoring to chaparral and not grass for grazing.”

Wildland firefighters detest chaparral for its ability to burn with untamable ferocity when driven by Santa Ana or sundowner winds. A 1960 Times story recounted efforts by the L.A. County Fire Department and the U.S. Forest Service to find “fire-resistant shrubs” to replace the natives.

“There is always the chance that scientists will find a slow-burning plant that will smother the chaparral,” a county fire official said hopefully.

The California Department of Forestry and Fire Protection plans to clear 14,000 acres of shrublands a year as part of a statewide fuels treatment program.

“Every Cal Fire person I know … wants to cut it down wherever they possibly can,” D’Antonio said. “[But] every time they cut a new fuel break, they put another strip of grasses on the landscape.”

University of California wildfire specialist Max Moritz in front of a dead stand of bigcone Douglas firs that burned in the 2007 Zaca fire. Mel Melcon / Los Angeles Times

Fire, then drought

Max Moritz slowly made his way up a hill, through a jumble of shrubs and fallen branches, to a graveyard.

Surrounded by dead bigcone Douglas firs, he scanned the slope for seedlings, searching for a sign that this patch of a unique Southern California mountain tree would survive.

“You don’t see anything,” he observed. “It has a fairly depressing quality to it, given the mortality and no regeneration.”

More than 11 years after the Zaca cut a 240,000-acre swath across Santa Barbara’s jagged backcountry, the landscape still bears scars.

The reach of 75-foot-tall flames is etched in towering tree trunks. Oak skeletons pepper the edge of the Dick Smith Wilderness.

Hillsides once blanketed with pygmy forests of chaparral are mottled with bare ground and clumps of young chamise and ceanothus shrubs. The ghostly profiles of dead bigcones rise from ridgelines.

Armed with thick bark and the ability to resprout from branches, bigcone Douglas firs are one of the world’s most fire-resistant conifers — built to survive the high-intensity wildfires that periodically chew through the chaparral that typically surrounds them.

The trees can be massive; one bigcone in the San Gabriel Mountains is as tall as a 15-story building. They can live for several hundred years.

Researcher Ryan Salladay extracts a coring from a dead bigcone Douglas fir. The tree burned in the Zaca fire but survived, only to die some years later. Mel Melcon / Los Angeles Times

So what doomed this old stand of bigcones off the Deal Trail? Was it the shooting flames of the Zaca, the brutal five-year drought that followed, or the one-two punch of both? Will these slightly goofy-looking conifers endure in the only part of the world they naturally grow?

Moritz, a cooperative extension wildfire specialist at the Bren School of Environmental Science & Management at UC Santa Barbara, and research assistant Ryan Salladay were looking for the answers.

Salladay spent hundreds of hours poring over satellite imagery and aerial photographs, looking for the distinctive star-shaped spread of bigcone branches. He digitally mapped bigcone patches in the footprint of the Zaca burn and created a time series of pre- and post fire images to date tree mortality.

Out in the Los Padres, research teams staked out 34 bigcone plots, each a tenth of an acre. They recorded the aspect of the slope and measured water stress in living trees. They studied post-fire soil surveys to see how severely the area burned in the Zaca. They checked for bigcone seedlings.

At Plot 3, Salladay drilled into a bigcone corpse with a simple T-shaped instrument and extracted a pencil-thin 3-inch coring.

A coring from a dead bigcone Douglas fir. Mel Melcon / Los Angeles Times

Back in his lab, he would mount the core on a board, gently sand it and examine it under a microscope. The width of the outer growth rings would tell the story of the tree’s final four decades.

The slender twigs still dangling from its bare branches provided a clue that the tree had managed to survive the Zaca and resprouted, only to die some years later.

“The drought-following-fire issue is a total reshuffling of what might come back or survive,” Moritz said.

Runoff from wildfires filled this pool in Rattlesnake Creek near Santa Barbara. The pool was once so deep that fisheries biologist Kristie Klose had to wear chest waders to check on rainbow trout, which disappeared after the blazes. Brian van der Brug / Los Angeles Times

A mounting toll

Kristie Klose, Los Padres’ fisheries biologist, hiked along a stream in Rattlesnake Canyon on the outskirts of Santa Barbara, stopping at a 2-foot-deep pool rimmed with boulders and mud.

Before the 2008 Tea fire and the 2009 Jesusita fire, the water was so deep that Klose wore chest waders when she checked the pool’s rainbow trout residents.

Now the water doesn’t even reach her knees. There are no fish to count.

The Tea and the Jesusita weren’t that big as recent Los Padres fires go. But they were cheek by jowl. The Jesusita burned the upper watershed and the Tea, the lower. Runoff from naked slopes dumped dirt and rocks into frontcountry creeks.

Hundreds of speckled native trout vanished. “They all got killed, buried and washed out to sea,” Klose said. “They’ve never recovered.”

These fires are so big — they take out so much contiguous country at once. Kevin Cooper, Los Padres forest biologist

Many of the Los Padres’ most imperiled species live in or near water: Southern California steelhead, red-legged frogs, arroyo southwestern toads and western pond turtles. When most of their watersheds go up in flames, they have no place to go.

“We’ve had back-to-back and juxtaposed big fires,” said Cooper, the forest biologist. “That doesn’t leave many refugia for these species to hide out in and recover and then repopulate and move back into the burned areas.”

One of those spots is miles to the north of Santa Barbara, just outside the boundary of the San Rafael Wilderness.

“You look at this and think, ‘This is nothing,’ ” Klose said, standing next to a shallow, slow-moving stretch of Munch Creek vital to steelhead spawning. “But it can be crucial to the whole system.”

Los Padres National Forest biologist Kevin Cooper stands next to Munch Creek, which provided refuge for steelhead after the Zaca fire. Brian van der Brug / Los Angeles Times

Endangered Southern California steelhead are the seagoing version of rainbow trout. Born in coastal streams, they migrate to the ocean as juveniles, mature there and then, salmon-like, return to natal streams to breed.

The 1993 Marre fire filled Munch Creek with fine sediment, driving out a small steelhead population. Five years later, rains cleaned out the silt. The steelhead returned, swimming some 35 winding miles from the Pacific Ocean.

Later, when runoff from the Zaca fire clogged a downstream creek, the fish hung out in Munch and Davy Brown creeks.

“It’s been tough. But they’re still in there,” Cooper said. “We want to maintain this habitat so they have a place they can survive in.”

An SUV drives across Davy Brown Creek on a concrete apron, which will be removed and replaced with a bridge to allow fish passage. Brian van der Brug / Los Angeles Times

To that end, the Forest Service is tearing out old concrete streambed crossings and replacing them with fish-friendly bridges to connect steelhead creeks.

But the money to do that — as well as pay for the Moritz and D’Antonio projects — comes from a one-time windfall of $20 million, which the forest collected in legal settlements with companies accused of negligently sparking the Zaca, Jesusita and Piru blazes.

As fire takes an ever bigger bite out of the Los Padres budget, there is less money for recreation, fish and wildlife management and trail maintenance. The permanent fire staff in the forest is now nearly four times the size of the non-fire staff.

In fiscal year 2006, firefighter salaries, equipment and fire station maintenance ate up 54% of the forest’s budget. In fiscal year 2017, nearly 68% of a $23.2-million budget went to fire. That doesn’t even include the enormous cost of fighting the conflagrations, which is covered by national Forest Service funds.

On the drive back to the forest office in Goleta, Klose and Cooper stopped at a turnout on Highway 154 south of Lake Cachuma.

Cooper looked across the rippling expanses of the Los Padres. That area burned in the Zaca and again in the 2016 Rey fire, he said. Over there was the 2009 La Brea fire. There, the 2013 White fire.

A distant ridge resembled a balding head.

“This piece by Little Pine Mountain is pretty bare now because of two fires in a row and the drought,” he said. “These fires are so big — they take out so much contiguous country at once.”

The fire-scarred mountains of Los Padres National Forest, seen from Highway 154. Brian van der Brug / Los Angeles Times

Produced by Sean Greene. Graphics by Thomas Suh Lauder.

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bettina.boxall@latimes.com