What Does the Future Hold for the Joshua Tree?

A starlit night at Joshua Tree National Park.
Getty Images

As the legend goes, it was 19th-century Mormon settlers who gave the Joshua tree its name, inspired by the plant’s bent and clubbed branches, which recall the biblical Joshua raising his arms in prayer. The etymology is apocryphal, but given the threats posed by climate change, these eccentric plants, and the California park named after them, might well need divine intervention—as well as new legal protections and conservation measures. 

Ringed by mountains and covering parts of the Mojave and Colorado deserts, Joshua Tree National Park’s rugged landscape features granite boulders, miles of cactus-filled flats, animals like the darkling beetle that can go a lifetime without a sip of water and the park’s namesake plant in all its twisted glory. 

Now completely arid, the land cradling the park once contained grasslands where mammoths and saber-toothed cats roamed; during the last ice age, giant ground sloths fed on Joshua trees, dispersing their seeds. The earliest known people in the area, the Pinto culture, were big-game hunters whose spear points have been found across today’s park. Even as the area warmed and dried, it has remained home to Native peoples—the Serrano, the Mojave, the Chemehuevi and the Cahuilla—who have drawn water from lush palm oases, gathered acorns and mesquite pods for food and used the tough leaves of the Joshua tree, which the Cahuilla call humwichawa, to weave baskets and sandals. By the mid-1800s, Native inhabitants were partly displaced by Western cowboys, ranchers and miners, whose long-abandoned homesteads are now disappearing under the sand. 

Among the park’s long history of defenders, Minerva Hamilton Hoyt—a wealthy Southerner who moved from Mississippi to California in the late 1890s and grew to love the desert—is foremost. She spent two decades seeking to protect the area from cactus poachers, leading Franklin Delano Roosevelt to designate it a national monument in 1936; it became a national park in 1994. (Hoyt is celebrated in a 5,405-foot-high mountain named after her, and in Mammillaria hamiltonhoytea, a species of cactus.)

Minerva Hamilton Hoyt worked with Secretary of the Interior Harold Ickes and others to protect the Joshua Tree region.


National Park Service

Today, driving past teddybear cholla cacti, one glimpses jackrabbits, roadrunners and coyotes. Surprisingly cozy campsites sit tucked amid giant monzogranite boulders that beckon rock climbers, and a short hike can bring you to a shady palm oasis perched atop an earthquake fault.

The Joshua tree, Yucca brevifolia, is a succulent—some botanists don’t consider it a tree. There are two distinct species: one with a tall, trunklike stem, one bushier. The plant’s contortions have won generations of fans. As author Jeannette Walls writes, “It’s the Joshua tree’s struggle that gives it its beauty.” 

Able to live for hundreds of years and rise more than 40 feet, the plants provide some of the park’s scarce shade. A keystone species supporting the area’s wildlife, Joshua trees—pollinated by a special species of moth—reproduce by bearing seeds. They offer shelter for pack rats and sharp leaves on which loggerhead shrikes impale their prey, and are a hallmark of the Mojave, which stretches across the park’s western half. To the east lies the Colorado Desert, a land of creosote, kangaroo rats and wildflowers that bloom after winter rains. 

In August 2020, a 43,000-acre fire killed more than a million Joshua trees in the nearby Mojave National Preserve. Though the plants have existed for some 2.5 million years, ecologists warn that they could be nearly eliminated in the park that bears their name by 2100 unless global warming is curbed soon. 

Already, botanists are seeing fewer juvenile Joshua trees, which need moister ground to survive. They’ve also seen “fairy rings”—circles of baby Joshua trees that sprouted not through pollination but as clones, unable to disperse; the plants’ unique pollinators, yucca moths, face an uncertain future as the climate warms. One conservationist calls the Joshua tree “a symbol of our utter failure as a society to address climate change.” The plant’s loss could mean the collapse of the Mojave’s high-desert ecosystem.

Nearly three million people visit the park each year, and entering vehicles back up for miles on busy days. With limited spots for camping and parking, many visitors flout regulations and camp or park on delicate lands. During a 35-day government budget shutdown in 2018 and 2019, vandals cut down Joshua trees and carved new roads through protected areas.

Meanwhile, smog from Los Angeles flows east through the San Gorgonio Pass, bringing ozone and soot. Nitrogen borne by smog fertilizes invasive grasses, which fuel wildfires that kill Joshua trees. 

Last year, California began debating whether the Joshua tree should become the state’s first plant protected by law because of climate change. Conservationists continue to remove invasive grasses, to bank seeds and to grow seedlings to replace Joshua trees lost in fires or windstorms. They’re also buying land so that Joshua trees can expand into cooler, higher pockets. The 19th-century explorer John Frémont may have called the plant “the most repulsive tree in the vegetable kingdom,” but those who love these gnarled treasures aren’t giving up on them, or on the park they call home. 

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Working to preserve the unique life-forms and ancient heritage of the Joshua tree’s habitat
By Rebecca Worby

Mojave Desert Land Trust Seed Bank

(Mojave Desert Land Trust)

Since 2016, this organization has collected seeds and spores from more than 500 Mojave Desert species to provide an insurance policy against the plants’ extinction. Specimens are harvested, cleaned, documented and stored in refrigerators. The group hasalready deployed seeds from the depository in restoration projects, including in places where wildfires have destroyed wide swaths of vegetation.

Native American Land Conservancy

(Native American Land Conservancy)

This group works to protect and restore sacred sites within the ancestral territories of the Cahuilla, Chemehuevi, Mojave and Serrano peoples of Southern California. Recently the conservancy acquired a petroglyph-filled area at the northwestern edge of the park that has been continuously occupied by indigenous peoples for thousands of years.

The Joshua Tree Genome Project

(The Joshua Tree Genome Project)

As climate change threatens to eliminate the Joshua tree, these scientists are working to sequence the plant’s genome. With help from citizen scientists and local conservation organizations, the project has also planted thousands of Joshua trees at four different sites that represent the climatic range spanning the Mojave. By monitoring these plants, scientists hope to pinpoint the genes that help seedlings survive.

Hardshell Lab's Tortoise Protection Technologies

(Hardshell Labs)

A major threat to the Mojave’s desert tortoise, listed as threatened under the Endangered Species Act since 1990, is a population boom among ravens. The birds hunt juvenile tortoises, whose soft shells offer little protection. Biologist Tim Shields founded a nonprofit that fields realistic “techno-tortoises”; when attacked, the 3-D printed replicas release methyl anthranilate, a non-toxic substance, derived from grape juice, that repels ravens—and conditions them to let baby tortoises be.

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#Nature | https://sciencespies.com/nature/what-does-the-future-hold-for-the-joshua-tree/