In 2020, the Dome Fire ravaged Southern California’s Mojave National Preserve, scorching nearly 70 square miles of biodiverse desert. The devastating blaze killed 1.3 million Joshua trees, including most of Cima Dome, one of the largest and densest Joshua tree forests in the world.
Then in 2023, the York Fire swept through, burning much of the neighboring Joshua Tree forest and killing as many as a million more trees. The destruction of Sima Dome, which is at a higher elevation and cooler temperatures than the surrounding desert, was a particular blow to the National Park Service and conservationists, who saw it as a stronghold for eastern Joshua trees and a key location for the species’ future.
Experts planned to turn Cima Dome into a refuge by removing invasive grasses and monitoring forest health, said botanist Andrew Kaiser, who worked at Mojave National Preserve at the time of the fire and now develops the Western Joshua Tree Conservation Plan for the California Department of Fish and Wildlife. “The perimeter of the 2020 Dome Fire was basically the exact contours of the model climate refuge. It overlapped almost perfectly.”
Research suggests that unless rising temperatures are mitigated, we could lose almost 100 percent of our trees in the coming decades.
The number of wildfires that have killed or damaged Joshua trees has skyrocketed in recent years, “and that’s largely due to changes in the desert ecosystem,” says Brendan Cummings, conservation director for the Center for Biological Diversity, who lives in Joshua Tree and is a leader in the fight to legally protect the trees. “Thirty years ago, a typical fire in the Joshua Tree forest would burn less than an acre. Lightning would strike the trees and knock them down. They rarely burned more than an acre.” Now, he says, larger fires are more common.
These fires are one of the major threats to Joshua trees, along with hotter, drier weather that kills seedlings and reduces new tree growth. 2019 and 2011 The study found that unless warming is mitigated, nearly 100 percent of range-wide trees in the southwestern U.S. could be lost in the coming decades — unless development, especially large-scale solar farms, kills them first.
The Joshua tree is a type of yucca that looks like something out of a Dr. Seuss book, with its hairy bark and jagged leaves at the ends of its curved branches. The Spanish called it the “Joshua tree.” Desert IzoteIt is a desert dagger, and the local Cahuilla people call it Hamuwichawa. Mormon settlers are said to have named the tree after the prophet Joshua, who raised his hands to lead the Israelites and keep the road wide. Mature trees can range from 75 to over 300 years old, with saplings taking about 30 years to reach maturity.
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There are two subspecies of Joshua trees: the Western Joshua Tree, which is found primarily in California and is home to Joshua Tree National Park, and the Eastern species, which is found in most of eastern California, southern Nevada, western Arizona, and a small corner of Utah. Both depend on one moth for pollination, but that moth does not pollinate the other species.
Joshua trees are also crucial to desert biodiversity. “Joshua trees are keystone species, enhancing habitat for other species and increasing biodiversity throughout the desert,” says Cameron Burrows, a former ecologist at the University of California, Riverside who studies Joshua trees. “From red-tailed hawks to great horned owls to Korean warblers to cactus wrens, their density and abundance is related to the availability of nesting sites, and Joshua trees are the only nesting sites in much of the Mojave Desert.”
Desert lizards use fallen branches for shelter, endangered desert tortoises feed on Joshua tree flowers, and black-tailed rabbits and desert mice depend on the moisture in the trunk tissue.
Climate change has contributed significantly to the changing fire regimes in the Mojave. A significant increase in burned area is due to rising temperatures, which increase the growth rate of invasive plants. Over the past 100 years, average desert temperatures have increased by 3.6 degrees Fahrenheit (2 degrees Celsius), and rainfall has decreased by up to 20 percent in some areas. As the driest region in North America, rainfall in the Mojave varies greatly but averages 5 inches per year. Joshua trees are highly adapted to the scorching heat of the Mojave, thriving in temperatures above 120 degrees Fahrenheit (49 degrees Celsius). However, they also need moisture, and climate change is bringing drought.
The York Fire destroyed approximately 1 million Joshua trees in the Mojave National Preserve in August 2023.
LE Baskow/Las Vegas Review-Journal/Tribune News Service via Getty Images
Climate change is expected to continue, Extreme fluctuations The weather in California will change dramatically over the next few years. The last few wet winters have helped new Joshua seedlings germinate, but their survival is not guaranteed. Joshua trees need a steady supply of moisture to survive the early stages of growth.
“Temperature is important, but precipitation is really important,” Burrows said. “When you combine warmer temperatures with dryness, you’re in big trouble.”
At the same time, wetter years help plant species that threaten Joshua trees. “Over the past few decades, invasive grasses originally introduced for cattle ranching and other reasons have taken over the Mojave. [changing] “Fire conditions are getting worse,” Cummings said. Grasses such as red oak and Mediterranean splitgrass are highly flammable and grow in abundance in wet years, sparking more intense and widespread fires.
Also, concern The introduction of invasive species, climate change, and atmospheric nitrogen deposition from smog in the Los Angeles Basin are all contributing to this. Stimulate growth Removing flammable grasses will prevent Joshua woodlands from regenerating after fire, and may instead convert the area into grassland with invasive species and low biodiversity.
Ironically, one of the biggest threats to the trees are the massive solar panels being built to reduce California’s dependence on fossil fuels.
Western Joshua trees are proposed to be listed as threatened under the California Endangered Species Act and are regulated by the state’s Western Joshua Tree Conservation Act, which prohibits cutting trees from private or public lands without a state permit, beginning in 2023. The federal government has denied federal endangered species protections for both subspecies under both the Trump and Biden administrations, most recently in 2023.
One reason they’re not protected is that there’s no shortage of Joshua trees right now; the threat is based on future loss projections. Eastern Joshua tree populations are estimated at several million, while western populations are as high as 10 million. Still, Cummings argues that both deserve protection because future projections are bleak. “When we look at the threat of climate change, we know we’re on a trajectory toward extinction,” he said. “If climate change stops at its current level, [still] They’re losing half their range.” Of course, temperatures are not expected to remain constant.
Another potential threat to Western species is development in the Mojave Desert, where half of the trees are on private land. (Most of the Joshua trees in the East grow on public land.) Ironically, one of the biggest threats to the trees are the massive solar arrays being built to help the state transition away from fossil fuels. The 530-megawatt Alatina Solar-plus-Storage project, to be built on private land near Boron, California, will kill about 4,000 Joshua trees and reduce habitat for desert tortoises and other species.
Desert tortoises, red-tailed hawks and black-tailed jackrabbits all depend on Joshua trees.
Daniel Elsbrock / NPS; Preston Jordan Jr. / NPS; Brad Sutton / NPS
Solar energy developers oppose listing the tree as endangered. They argue that the California desert, along with North Africa, receives the most solar radiation in the world, making it ideal for generating electricity. “Our grid capacity will need to expand in ways that are almost unimaginable,” Shannon Eddy, executive director of the Large-Scale Solar Energy Association, told Vice News. “We’re only just at the forefront of figuring this out, so it’s not right to close vast swaths of the desert to solar development before we really know where we’re going to go.”
The Western Joshua Tree Protection Act, which inherited some solar projects, was enacted when the California Department of Fish and Wildlife was deadlocked on whether to list the subspecies as endangered. A political compromise, the law passed because it allows more flexibility for management than listing the trees as endangered.
The law requires the Fish and Wildlife Service, working with other government agencies, California’s Native American tribes, and the public, to develop a proposed conservation plan for the species by December 31, 2024, and requires companies to purchase permits to cut or transplant Joshua trees. Permit fees would contribute to the creation of a conservation fund. The plan aims to protect not only the trees, but the broader Mojave Desert ecosystem, including arborvitae, desert tortoises, burrowing owls, rare plants, yucca moths, and other species, from development pressures.
“It’s by no means perfect,” Cummings said, “but it will bring things into a rational, orderly, lawful space. High desert communities have done a really great job protecting their desert landscapes from development.”
National Park Service botanist Drew Kaiser surveys invasive red oak trees in the Mojave National Preserve.
Irrfan Khan/Los Angeles Times via Getty Images
One important part of the new conservation strategy is paper Published in the journal Biological ConservationThe goal of the refuge is to protect trees in the refuge, a designated area of ​​Joshua Tree forest that is healthy and cooler as temperatures rise and less susceptible to drought. In Joshua Tree National Park, managers are mowing the refuge, removing fuels and creating firebreaks between the trees.
Researchers are also mapping tree genomes to predict which trees will be most tolerant to heat or drought, then prioritizing those trees for protection or using their seeds for replanting.
Assisted relocation, which would involve physically moving mature trees to Northern California or Oregon, is being considered. But “we can’t just move the Joshua trees,” says Kaiser of the California Department of Fish and Wildlife. “We need to move the nursery trees.” [which help seedlings get established]”We have to relocate the yucca moth pollinators. We have to monitor them. All the studies we’ve seen so far indicate that’s not a viable option at this point, but we haven’t ruled it out.”
Despite these threats, there are some silver linings: Increased use of electric vehicles in Southern California, for example, could reduce levels of atmospheric nitrogen that promotes the growth of flammable grasses.
And there’s a broad range of efforts by the partners involved. “In areas that are well-managed, like the national parks, I’m optimistic,” says Burrows of the University of California, Riverside. “What’s interesting is that in some areas the trees are actually encroaching into the pine forests and doing very well because they’re at higher elevations, they’re cooler, they’re wetter. So Joshua trees as a species won’t go extinct, but unless we reverse the climate change problem, areas of the Mojave Desert will be ecologically even poorer if they lose Joshua trees.”
