MOJAVE NATIONAL PRESERVE, Calif. — Driving certain back roads in this sprawling desert park is like traveling through time. Along the dusty paths, a stark picture emerges: On one side of the trail, a vibrant ecosystem; on the other, a charred graveyard of Joshua trees. This is the preserve before and after fire.

Those who know the park well can rattle off the names and dates of the blazes that seared these split-screen images into the desert: the Hackberry Fire, 2005; the Dome Fire, 2020; and now the York Fire, which ignited July 28 and has torn through more than 90,000 acres, becoming California's largest inferno this year and torching an untold number of cherished Joshua trees and other protected plants.

For the Joshua tree — a wild and whimsical internationally recognized symbol of California — fire has become an existential threat. Because its delicate desert habitat did not evolve with major wildfires, the Joshua tree is especially vulnerable to flames. When they burn, they burn fast. And they rarely survive.

That's of particular concern at this Southern California preserve, where fires were once uncommon but are now increasing in frequency and ferocity. Officials at the 1.5 million-acre park are still assessing the latest damage, but it appears to be catastrophic, said deputy superintendent Debra Hughson, who compared the devastation to the Dome Fire, which burned more than a million Joshua trees.

"The landscape is changing in front of my eyes," said Hughson, who has worked in the Mojave for more than two decades. "It's losing something you love and you'll never get back. Generations from now, people could be born who never see a Joshua tree, like the passenger pigeon."

The York Fire sparked at a crucial moment for Joshua trees. One of the plant's two species recently received protection under state law, which will help shield it from the sprawl and development that has endangered its habitat. But as the second large fire in three years took a heavy toll, some are now reckoning with the possibility of a future without Joshua trees.

In California, where residents have learned to dread fire seasons that keep breaking records, this year had been eerily quiet. But the York Fire, fueled by grasses that grew tall during heavy winter rains and dried out in recent heat waves, could be a sign of what is in store for the coming months, experts say.

The fire, which started on private land inside the preserve, had grown to 93,000 acres by Friday, more than four times the size of all the season's previous fires combined. Some 9,000 acres burned across the border in Nevada, scorching America's newest national monument, Avi Kwa Ame.

By week's end, the fire was mostly contained. But the damage was already done.

'Huge unknowables'

Hughson could feel the danger before it arrived. She was surveying the preserve last month, driving a gravel road into its New York Mountains. She looked warily around at the thick scrub, brush and grasses.

"Man, this is going to burn," she said to herself. "For me, it's a sense of inevitability."

The greater Mojave Desert, home to Death Valley, was already one of the hottest places on Earth. But rising temperatures and the changing climate has also altered the region's so-called "fire regime," the pattern of wildfire occurrence. It is now considered a "climate change hot spot," characterized by drier dry spells and wetter wet years.

"This is a place that has historically rarely ever burned," said Terry McGlynn, the director of the California Desert Studies Center, which is located at the Western edge of the preserve. "So it's unprepared for the fire. The seeds of desert plants aren't prepared to regenerate after fire."

For that reason, it's difficult to predict what a recovery from fire might look like.

"As an ecologist, what I see are huge unknowables," McGlynn said.

But it is clear the land will not be the same. Joshua trees high mortality rates during fires, and scientists estimate the preserve's pinyon-juniper woodlands, which are full of hardy evergreen plants that thrive in higher elevations and rocky soil, could take up to three centuries to return to something like their pre-fire state.

Examples of long-lingering wounds were obvious on a visit to the preserve this week. In Cedar Canyon, a remote area near the middle of the park, pinyon-juniper covers the north side. On the south, gray tree skeletons dot the hills. This is the aftermath of the Hackberry Fire, which burned more than 70,000 acres and still pocked the ecosystem some 18 years later.

Northwest, in and around Cima Dome, one of the densest and largest Joshua tree forests in the world, the land is littered with the consequences of the Dome Fire. Here, it was the high concentration of plants rather than the burn radius — about 44,000 acres, far less than the York Fire — that led to so much destruction.

The effect is especially visible along Morning Star Mine Road near Cima, where one side of the street is home to thick stretches of green, spiny Joshua trees, while the other is covered in their carcasses, which stood like bouquets of burned toilet brushes against the blue afternoon sky.

Scenes like these will become more common as the climate warms, said Justin M. Valliere, a plant sciences professor at the University of California at Davis who has studied what is known as the invasive grass cycle. It goes like this: After fires, landscapes like the Mojave can become more vulnerable to invasive species, which then grow faster and promote more fires, continuing a positive feedback loop.

Valliere's research, which has focused on coastal ecosystems, has linked fossil fuel emissions to increased invasive plant growth. Other studies have shown the phenomenon is occurring in the Mojave, meaning that exhaust from vehicles driven around car-choked Los Angeles can send nitrogen deposits all the way to the desert, fertilizing invasive grasses like red brome.

"Invasive grasses in the Mojave Desert are completely altering the fire regime there," Valliere said, "and leading to more frequent fires."

'Grotesque yet magnificent'

These threats have led to increased Joshua tree preservation efforts. Advocates, who scored a big victory with the June passage of the Western Joshua Tree Conservation Act, are now turning their focus to fire.

But the mere fact that a legion is willing to fight for their survival is a big win for Joshua trees, which have not always enjoyed such reverence in American culture. The earliest reports were tough.

"Their stiff and ungraceful form makes them to the traveler the most repulsive tree in the vegetable kingdom," wrote the explorer and eventual U.S. Sen. John C. Frémont in 1845, penning its first-known English language description.

Nearly a century later, public opinion had softened, slightly. A magazine article from the 1930s described them as "grotesque in the extreme ... yet they are magnificent."

Now, however, the plant is iconic.

It appeared on the artwork for one of the best-selling albums of all time, U2's "The Joshua Tree," and has been visited and photographed millions of times by people from across the world. It has entered the echelons of California's most charismatic flora, along with the coastal redwoods, giant sequoias and bristlecone pines.

If those are the tallest, largest and oldest trees, the Joshua tree is perhaps the strangest. Stranger still: It's technically not even a tree, belonging instead to the yucca genus.

"They have that awkward, gangly, Seussian countenance," said Brendan Cummings, the conservation director at the nonprofit Center for Biological Diversity. "Maybe they remind us of ourselves and the tensions we have in the world. They can simultaneously be magical but odd."

After the Dome Fire, volunteers undertook a massive effort to plant 1,500 Joshua tree seedlings alongside thousands of their burned forebears. "It's really a lot to take in," a firefighter who traveled from New Mexico told the Los Angeles Times then, looking around at the scorched trees.

Cummings was in that group, and he said more such efforts will be needed following the York Fire. Preserve officials were able to estimate the number of plants claimed in the Dome Fire because it burned on research plots, where scientists knew how many Joshua trees grew and could estimate the total loss.

But after the York Fire, that calculation is impossible. Cummings estimates the number is probably several hundred thousand.

"While the preserve has been fundamentally transformed by this fire, it's still a critically important ecological area that should be the focus of restoration efforts," he said. "The land is still worth protecting beyond that."

On Thursday, in the southern swath of the burn scar, the hot air still smelled of bonfire. Plumes of smoke were visible in the distance. Near a campground flying a tattered American flag, what appeared to be acres of freshly burned Joshua trees stretched across the land. Parts of the sandy ground were singed black. One tall plant had toppled into the road.

Conservationists have said it is sometimes difficult to convince members of the public to care about the desert the way they might about, say, a redwood forest. This environment is often mistaken for a desolate wasteland. But the desert is home to thousands of ecologically important species: rare plants, mammals, birds and the endangered desert tortoise, California's state reptile.

Scientists, advocates and park officials are desperately trying to keep it that way.

"The desert is not an empty wilderness," said McGlynn, of the Desert Studies Center. "It is full of life."