海角大神

Threatened by fire, iconic Joshua trees battle for survival

In California鈥檚 Mojave National Preserve at the peak of summer, the desert鈥檚 iconic Joshua trees rise from a dusty landscape. The spiky Joshua tree evokes strong reactions: weird, unique, whimsical 鈥� and more often than not, a reference to Dr. Seuss. It鈥檚 also a plant at risk.

The calm quiet of the desert belies its dangerous, unrelenting heat. In the northeast corner of the vast Mojave preserve, that heat fed the York wildfire that started聽听补苍诲,听, had scorched more than 93,000 acres of prime Joshua tree habitat. Scientists are still assessing the damage, but the York Fire was twice the size of one from three years ago that killed more than a million Joshua trees. The trees grow nowhere else on the planet but here in Southern California and part of Nevada.

鈥淭he unfortunate thing is that Joshua trees are very susceptible to fire,鈥� says Sasha Travaglio, a spokesperson for the National Park Service, which oversees Joshua Tree National Park and the nearby preserve, which actually holds many more trees than the beloved park. The plant鈥檚 pulpy trunk is fast fuel for flames, 鈥渁nd so usually when they burn, they do die.鈥�

One massive event, like the York Fire for instance, could mean the plant鈥檚 devastation. But there鈥檚 hope in efforts to keep that from happening.

Experts, through trial and error, are trying to ensure the plant鈥檚 long-term survival, says Sierra Willoughby, supervisory park ranger for the Mojave preserve. 鈥淭rying to go in there as human beings to replant things can be really tough here. ... There鈥檚 no guidebook about how to restore a Joshua tree forest. It鈥檚 something that you have to experiment with.鈥�

A distinctive plant

The Joshua tree, which is actually a yucca plant, is wholly unique to the high deserts of Southern California and part of Nevada. The Mojave preserve鈥檚 1.6 million acres nestle up against the Nevada border, and span three of North America鈥檚 four major deserts. The eastern Joshua tree that grows in the preserve is distinct from its western cousin, which lives farther south in Joshua Tree National Park.

This is where Bob Oviedo picnics in the desert sun of Joshua Tree National Park with his two small dogs. 鈥淚t鈥檚 amazing that there鈥檚 so much growth here in the desert, with the heat that we have here,鈥� says Mr. Oviedo, who lives about 45 minutes away in Palm Desert. He stopped in the park after a work trip nearby.

The park is so beautiful, he says, that he doesn鈥檛 want to waste a single chance to appreciate it. 鈥淵ou have a variety of trees and bushes and cactus here. But it鈥檚 mainly the Joshua trees that are very pretty, and they stand out.鈥�

The eastern and western plants have subtle, but essential, differences. Each depends on its own specific species of yucca moth for pollination; both species thrive in similar habitats, but not the same ones. If they could survive on each other鈥檚 turf, they probably already would, says Lynn Sweet, a research ecologist with the University of California, Riverside. They look different, too: The trunk of the western plant grows 4 or 5 feet before it branches, and looks more like a tree. The eastern species grow branches closer to the ground in a V shape 鈥� although both species can grow quite large.

And they share a name rooted in folklore. The most popular theory is that Mormon migrants named the plant for the biblical Joshua, whom they saw reflected, with arms stretched upward to the heavens, in the yucca鈥檚 unique shape.

Learning from past fires聽

The eastern Joshua tree is struggling for survival at the Mojave preserve鈥檚 Cima Dome, a rounded granite mountain west of the York Fire. A 聽at the dome consumed 1.3 million Joshua trees, leaving large swaths of scorched earth. 鈥淲e鈥檙e going to have a different forest here now,鈥� says park ranger Mr. Willoughby.聽

Climate change is driving the plants 鈥撀爓hich require some water, and thrive in climates that run both hot and cold 鈥撀� to higher elevations. The dome area offered prime habitat, but Joshua trees do not grow back once they fully burn. The ground sloths that once spread the Joshua tree seeds to this relic forest have been extinct for thousands of years. Small mammals are mostly responsible for the plants鈥� modern migration, which means seeds travel short distances and stay close to areas with lots of vegetation. Human intervention is especially needed where the landscape is completely charred and Joshua trees are too far gone to regenerate on their own.

Today, a forest of blackened Joshua trees is the backdrop for sporadic, budding life. The smell of smoke still wafts from the plants鈥� burnt fibers. In some places, clusters of baby Joshua trees sprout from shrubs or from the roots of other plants that burned and toppled over.聽

The preserve鈥檚 two vegetation technicians are managing an effort聽to plant 4,000 eastern Joshua tree sprouts in the dome burn area. The sprouts are raised from seed at the Lake Meade National Recreation Area in Nevada, and then transplanted and monitored by hundreds of volunteers in multiday camp-outs on the preserve. Nearly 1,900 trees have been planted so far. Sixty to 70% of those have not survived.聽

Tentative recovery

Nearly 5,000 feet above sea level, off an unpaved access road that winds into the Cima Dome burn scar, blackened Joshua trees stretch as far as the eye can see. This is prime habitat for the plant, and where re-wilding has had sporadic success.

A cylindrical wire cage protects a small green sprout. 鈥淭his is the only one that鈥檚 still green and viable,鈥� says Mr. Willoughby. 鈥淎ll the other ones are dead.鈥� Five other cages, placed about 30 feet apart, wrap around failed plantings. But in the trial and error of re-wilding, even these failures have value. 鈥淏y far, it was very clear from the data that you needed to have the plant protected from predators like rodents, or that they were just going to get eaten alive.鈥� Uncaged transplants had even smaller chances of survival.聽

Nature brings its own slow recovery, too, though it may come with a new, less dense, trajectory. 鈥淰isually it just looks like utter devastation, and it鈥檚 barren for a long time,鈥� says ecologist Dr. Sweet. 鈥淏ut we also know that there are new shrubs. ... Some of those are able to re-sprout; some of the trees are able to re-sprout. So things can recover as long as conditions continue to be reasonable.鈥�

Drought and changing temperature patterns make that recovery more difficult, threatening not only the iconic Joshua tree forests, but also the desert ecosystem. 鈥淭hey hold a variety of plant communities, a variety of animal communities,鈥� says Dr. Sweet. 鈥淭hey鈥檙e also hosting a whole biota underground that we can鈥檛 see. And those are actually functioning to store things like carbon, which is really important globally.鈥�

The U.S. Fish and Wildlife agency, in March, list Joshua trees as endangered species, saying the threats to the plant didn鈥檛 rise to the level needed for that designation. California, however, passed the a few months later, stepping up protections for that species by prohibiting its unauthorized export, import, or sale anywhere in the state.聽

鈥淣atural sculptures鈥�

August in Joshua Tree National Park brings high heat, and low season. This is where the Mojave and Colorado deserts come together, where beige rock formations frame desert vegetation, which adds shades of brown and muted green. There are no bright colors here 鈥� only the bright sun, which drives reptiles and rodents underground and into shadowy crevices.聽

The conditions force visitors and locals alike 鈥渢o respect the ecosystem,鈥� says park ranger Ms. Travaglio, talking among Joshua trees atop the park鈥檚 Black Rock Campground 鈥撀爋ne of the plants鈥� healthier habitats.聽鈥淲e can鈥檛 control it. It can kill us. And we have to be well prepared, well educated, and aware while we are either recreating or living in the desert.鈥�

It takes a moment for small creatures to make themselves known 鈥撀燽ut stand still long enough, and the chittering of life grows audible, if not visible. A lone bird hops inquisitively a few feet away. Twitch to grab the camera, and the bird is gone.聽

The heat is not ideal, says Grazia Giordano, who is visiting from Milan. But the Joshua trees are 鈥渁mazing. They look like natural sculptures; they are like in a plastic pose ... and creating such a magic picture of the land.鈥� Visitors to the park this time of year 鈥撀爉any of them European 鈥撀爏ay they鈥檙e willing to brave the harsh, dry heat for an experience they won鈥檛 find at home.聽

Joshua trees grow slowly, about an inch a year, and live upward of 100 to 200 years. That longevity brings peace to artist Shari Elf, who runs a shop in the town of Joshua Tree called Art Queen.

鈥淲hen I look at an older one, I鈥檓 moved to think about how old it is. ... And I respect that,鈥� says Ms. Elf. 鈥淚 think about all of the decades or ages they鈥檝e been through, witnessing all of us, and me, and my little petty problems. And they鈥檝e seen it all. They stand tall and strong.鈥�