An Iconic American Tree Is Threatened by Climate Change

Image via Wikimedia Commons user Jarek Tuszynski (aka Jarekt)

Legend has it that Mormon travelers named the iconic Joshua tree for the Bible story; its outstretched limbs, they said, looked like a man in prayer. According to new research discussed this week in National Geographic, this species of yucca plant, which is native to Southern California and other sections of the Southwest, may indeed need help. Researchers say the tree is seriously threatened by climate change.

The issue comes down to the Joshua tree’s roots, as Cameron Barrows, an ecologist at the University of California, Riverside, told Nat Geo’s Osha Gray Davidson. Full-grown Joshua trees have shallow root networks that are able to suck up rain as soon as it falls in the desert where they live (mostly in the appropriately named Joshua Tree National Park in Southern California). “The big guys just need a good rainstorm every other year,” Barrows said. But the tree’s seedlings have not yet established that extensive root network, and need more regular rain to survive.

Enter California’s megadrought—a phenomenon that scientists say will only become more frequent as the effects of climate change effects persist. While completing the first survey in a 20-year biological study of the Joshua Tree region, Barrows discovered that in about 30 percent of the Joshua trees’ habitat, there are few young trees. “In some areas we surveyed, there are no baby Joshua trees at all,” he said.

Joshua Tree National Park

Based on climate change models, Barrow concludes that drought could reduce the range of the Joshua tree by a whopping 90 percent by 2100. “Under that scenario, [the tree] would exist only in isolated pockets, called refugia, scattered across the 800,000-acre national park,” Nat Geo reports.

That’s a dire prediction, and dire enough, some environmentalists say, to land the Joshua tree on the endangered species list. In September, the New Mexico-based WildEarth Guardians announced that they would petition the U.S. Fish and Wildlife Service to classify the Joshua tree as “threatened” under the Endangered Species Act. A listing would increase the regulatory protections against the yucca.

That’s not quite sufficient, Barrows told Nat Geo. “Climate change is an international issue,” he said, not one that can be handled by just the Fish and Wildlife Service.

But the tree certainly does need help. So do other plants. A study released earlier this year found that extreme weather produced by climate change could reduce the world’s plants’ growing days by 11 percent in less than a century.

“Those that think climate change will benefit plants need to see the light,” said Camilo Mora, the ecologist who headed that study.