Dear EarthTalk

Are the famous Joshua trees of the California desert really going extinct? What can we do to preserve them?

Bill Alexander, Tempe, AZ

The Joshua tree is an iconic species of the Mojave Desert that stretches across parts of southeastern California, Nevada, Arizona, and Utah. Known for its resilience in an unforgiving desert climate, the Joshua tree is unique in its unusual anatomy and adaptable ecology, but its future looks bleak in the face of increasing global warming.

Indeed, increasing temperatures and decreasing precipitation thanks to climate change have shifted the suitable habitat for a variety of flora and fauna around the world, including the Joshua tree. Biologists fear that little of the Joshua tree’s historical range will be suitable for it within a century. By 2100, climate models show that Joshua Tree National Park will lose the majority of its suitable habitat for its namesake species. The increasing severity and frequency of forest fires pose a threat to the future of the trees as well. Because Joshua trees did not evolve with fire, they are not adapted to its effects, making it difficult for the population to bounce back after such a disturbance. As temperatures increase, biologists predict that the suitable range for Joshua trees will move northward. However, this northward range is not guaranteed to be viable, as the Yucca moth that pollinates Joshua trees does not live up there.

Given the threat to Joshua trees, several entities have embarked on campaigns to try to save the iconic tree. The National Park Service recently embarked on a campaign to protect the tree’s remaining habitat in Joshua Tree National Park, Mojave National Preserve and Death Valley National Park. Meanwhile, researchers and conservationists launched the Joshua Tree Genome Project in 2020 to collect and monitor data from both professional and citizen scientists in an effort to map and monitor existing populations. Project organizers hope to use the data to inform conservation planning by identifying Joshua tree populations best situated to benefit from conservation protections. Yet another effort to help Joshua trees comes from the Mojave Desert Land Trust, which recently launched a planting program to restore lost habitat for the trees across the Mojave.

Public education about the importance of saving threatened species is also key to saving Joshua trees. To wit, the non-profit Joshua Tree National Park Association is working to educate the public about the importance of Joshua trees and the threats they face through free educational programs and resources for visitors to Joshua Tree National Park.

Yet while Joshua trees were granted temporary protection under the state of California’s endangered species laws, they are as yet unprotected at the federal level. As such, the non-profit Center for Biological Diversity has petitioned the U.S. Fish and Wildlife Service to protect the Joshua tree under the Endangered Species Act.

CONTACTS

• Joshua Tree Genome Project, joshuatreegenome.org;
• Saving Iconic Joshua Trees, chicagobotanic.org/blog/plant_science_conservation/saving_iconic_joshua_trees
• California Commission Deadlocks on Protecting Western Joshua Trees as Threatened Species, biologicaldiversity.org/w/news/press-releases/california-commission-deadlocks-on-protecting-western-joshua-trees-as-threatened-species-2022-06-16/.