National Parks Traveler

The Dome Fire laid waste to a Joshua tree forest at Mojave National Preserve/NPS, Drew Kaiser

Joshua Trees: An Uncertain Future For A Mojave Desert Icon

By Hilary Clark

A sea of scorched Joshua trees, reduced to black skeletons of their former selves, darkens eastern California’s Mojave National Preserve. The pungent smell of their charred remains lingers even after January snowfall.

Mojave National Preserve vegetation program manager Drew Kaiser forewarns: “When you first see the burned area, you have to brace yourself—it’s heartbreaking. It’s just miles and miles of bare, scorched earth and the ghostly remains of what this beautiful forest once looked like.  However, every so often you’ll come across an unburned patch of vegetation. This gives me some hope.”

Last August 15, a lightning bolt ignited the Dome Fire, which roared across 43,273 acres and through the heart of the Joshua tree forest in Mojave National Preserve. The flames consumed an adobe bunkhouse at Valley View Ranch, an historic ranch house and outbuildings at Kessler Springs, and charred more than one million Joshua trees. Kaiser and other staff members are particularly concerned that red brome, a highly flammable, invasive grass, may have contributed to the immensity of the fire.

“When desert ecosystems burn too frequently, species not adapted to fire, like blackbrush and Joshua trees, will be permanently lost,” said Kaiser. “Red brome is highly adapted to fire and will cause these areas to burn again for shorter time periods, thus, initiating a feedback loop or fire-grass cycle, which is hard to break.”

The National Park Service’s response to naturally occurring fires typically is to let nature take its course. But Kaiser believes the circumstances surrounding the Dome Fire were unnatural. Climate change was a driver with extreme weather events, such as prolonged drought conditions in the western United States. Over 100 years of cattle grazing on Cima Dome also added fuel to the fire. Cattle tend to forage on the nutritious, easily digestible plants first, like perennial bunchgrasses. As cattle forage on bunchgrasses, the woody vegetation builds up, which leads to a more intense fire.

The Joshua tree forest was a magical place to explore before the Dome Fire/Hilary Clark/

Throughout the 1940s, Mojave National Preserve was home to a mineral springs and health resort called Zzyzx, established by Curtis Springer. After his mining claims in the area turned him into a millionaire, Springer built a two-story castle, a dining hall, library, and lecture hall that greeted guests upon their arrival to the resort. Springer also had a popular radio show and sold “health” products to customers all over the country. By the late 1960s, customer complaints began to mount, and his fraudulent business began to crumble. After serving jail time, he quietly lived out the rest of his life in Las Vegas. The Zzyzx structure now belongs to California State University. Learn more about this location in the book Mojave National Preserve or bring home an official park product from Western National Parks Association.

Under normal circumstances, the tallest Joshua trees can survive a light, flashy fire fueled by perennial bunchgrasses and can continue producing fruit and seeds that would lead to the natural reforestation of Joshua trees. However, in his burn severity assessment, Kaiser saw vast areas of big and small Joshua trees that were fully burnt and not likely to survive. Given these circumstances, the Park Service is taking action.

Back in 2018 the preserve staff began working with their colleagues at Lake Mead National Recreation Area to collect seeds and begin growing 1,500 Joshua trees. The initial intent of this project was to plant these two- to three-year-old trees in areas disturbed by human activities. Now, with the recent fire, the staff is changing course. They are planting the trees in the interior of the burned area—hoping one day to provide the necessary source of seeds for the natural reforestation of Cima Dome.

“Cima Dome has been modelled as a refugia for Joshua trees—a place where they can persist in the face of warming temperatures,” Kaiser emphasized. “It is important for us to reestablish this keystone species on Cima Dome and ensure the continuation of its current range as it loses habitat in the future.”

But, he adds with a cautionary note, “there are many obstacles in the way.”

This map shows how the fire, outlined in red, burned across desert tortoise habitat/NPS, Neal Darby

These iconic trees threatened by climate change have a history as unique as their twisted forms, which some observers adore and others detest. While the Mormons who named the trees thought their outstretched branches resembled the biblical figure raising his arms in supplication, 19th century explorer John C. Fremont believed “their stiff and ungraceful form makes them to the traveler the most repulsive tree in the vegetable kingdom.”

Joshua trees are not actual trees, but members of the yucca family. Unlike sequoias that need heat to release seeds from their cones, Joshua trees rarely resprout after a fire. As intense fires occur in its home range, threats to this popular desert plant mount. 

Some studies predict that by 2100 western Joshua trees (Yucca brevifolia) will be extinct from the southern portion of Joshua Tree National Park. These trees are generally taller and more spindly than eastern Joshua trees (Yucca jaegeriana), located about 90 miles away in Mojave National Preserve. Last September, the State of California declared Joshua trees an endangered species and gave them temporary protection. The endangered status lasts for about a year, giving scientists time to further evaluate the threats to the trees. This marks the first time the state has used the California Endangered Species Act to specifically protect a plant threatened by climate change.

Joshua trees only grow in the Mojave Desert, which includes an area about 54,000 square miles mostly in California and Nevada with small sections of Arizona and Utah. They are usually found around 2,500-5,000 feet in elevation and can live an average of 150 years.

Joshua trees don’t reproduce quickly, and rely greatly on other creatures to give them a helping hand.  More than 13,000 years ago the bear-sized Shasta ground sloth, which has been described as “resembling a fuzzy Volkswagen Beetle,” ate fruits and seeds from Joshua trees. It walked about ten miles a day and dispersed the seeds through its dung.

At the end of the last Ice Age, temperatures warmed, and the Shasta ground sloth went extinct. This essentially froze Joshua trees in their current range. Today, much smaller animals such as pack rats and the white-tailed antelope ground squirrel help spread Joshua tree seeds, but their little legs only travel so far. On average, these rodents will only travel about 100 feet from their burrow to gather food—a main staple being Joshua tree seeds. Any uneaten seeds burrowed by these critters stands a chance to germinate, but the range of dispersal pales greatly to that accomplished by the sloth.

The pack rat dwarfs one of the Joshua trees most important evolutionary partners—the yucca moth. In the spring, creamy white flowers on the tips of the Joshua tree branches attract these moths. They are the Joshua tree’s only known pollinator in the world. By crawling into the flowers to lay their eggs, the moths collect pollen on their bodies and transfer it to other flowering Joshua trees. In turn, when the eggs hatch the larvae find nourishment in the Joshua tree seeds.

In 2003, scientists discovered that a different yucca moth pollinates the eastern Joshua trees in Cima Dome. Built for the job, the moth’s size matches the distance from the flower’s ovule to the stigma. This discovery elevated eastern Joshua trees to a separate species from western Joshua trees.

The fire didn't seem to have a great impact on desert tortoises in the preserve/NPS

It is unknown how the Dome Fire affected yucca moths. However, Mojave National Preserve wildlife biologist Neal Darby has determined the fire’s overall impact on another desert resident, the desert tortoise, is “negligible.” Cima Dome has about 42,000 acres of designated critical desert tortoise habitat. Yet, as it rises more than 4,100 feet in elevation, this area is higher than the lower elevations where desert tortoises generally dwell, and the reptiles have difficulty building their burrows in Cima Dome’s shallow and coarse sand. In the past 20 years, Park Service surveys have documented only three desert tortoises in the recent burn’s perimeter—not even a carcass.

The listing of the desert tortoise as a threatened species under the federal Endangered Species Act was key for the establishment of Mojave National Preserve under the 1994 California Desert Protection Act. This act elevated Joshua Tree and Death Valley national monuments to “national parks,” adding more land and a higher level of protection to both sites. The preserve sits between Death Valley National Park to the north and Joshua Tree National Park to the south. It also serves as a transition zone where the Mojave, Sonoran, and Great Basin Deserts intersect. 

The preserve boasts towering sand dunes, extinct cinder cones, and an extensive Joshua tree forest. In addition to the natural scenery, it has important cultural sites and rich Native American, railroad, and mining history. There are few signs, no gas stations, and no restaurants or convenience stores within its boundaries. It can be a daunting landscape for those more accustomed to developed national parks, but for people looking for an adventure, there are hundreds of miles of dirt roads to explore and rugged terrain to hike.

When I worked as a park ranger at the Kelso Depot Visitor Center from 2009-2012, I experienced this landscape firsthand, living among the Joshua trees in Cima where the Dome fire burned.  I rode my mountain bike on the dirt roads through hundreds of Joshua trees of all shapes and sizes. Their silhouettes looked particularly magical during full moon nights or at times when there was a sea of stars in the jet black sky.

Like others who have spent time in this Joshua tree forest, the Dome Fire has left me with a profound sense of loss. But I learn from Kaiser that there’s a way that I and others can make a difference. He and his colleagues need help planting, watering, and putting fencing around Joshua trees in Cima Dome this upcoming winter. If you’re interested in volunteering, please contact the Mojave National Preserve by phone at (760) 252-6100 or by email at: [email protected]

Hilary Clark has worked as a park ranger for the National Park Service at national monuments, historic sites, national seashores, and national parks from the East Coast to the Southwest. 

This story was made possible in part by Western National Parks Association.

Lost to the flames/NPS, Barbara Michel