Joshua trees
Atwo-hour drive east of Los Angeles, there was once a desert oasis known as the Devil’s Garden where woolly clusters of pincushion cacti flourished alongside pungent creosote bushes and all manner of sword-leaved yucca. In the early 1900s, as southern California’s population surged, and a fascination with unusual desert species intensified, tourists and gardeners pillaged the local Eden. To create nighttime beacons for fellow visitors, some people even set fire to one of the tallest plants around, the Joshua tree, a member of the yucca tribe with meandering, almost tentacular branches erupting in spiked green crowns.
This botanical ransacking sickened Minerva Hoyt, a Pasadena gardener and civic activist. She began designing elaborate exhibits of live cacti for garden shows in New York, Boston and London. And she continually petitioned the government to protect desert wilderness. In 1936, thanks to her efforts, President Franklin Roosevelt established the 825,000-acre Joshua Tree National Monument, most of which became a national park in 1994.
Today, the creatures Hoyt loved are endangered by a much more insidious force. The Joshua tree is now consumed by an invisible blaze of unparalleled magnitude. Researchers project that by the year 2100 temperatures in the American Southwest will rise by as much as 5 degrees Celsius (9 degrees Fahrenheit) and annual rainfall will decrease substantially. Some studies predict that a 3-degree Celsius increase in average temperature in the next century will eliminate 90 percent of all Joshua trees and up to 98 percent of the trees in the national park. “I think things look really bad for Joshua trees,” said Christopher Smith, a biologist at Willamette University.
Adult trees can survive several years of low rainfall, but young trees “don’t have nearly the same root system or water storage capacity, so long droughts toast them,” said Cameron Barrows, a University of California, Riverside, ecologist. At some lower elevations of the Joshua tree’s range, which are hotter and drier, there are hardly any baby trees at all.
The Joshua tree’s relaxed pace of life further hinders its survival. Joshua trees live for centuries, waiting until about age 20 to start producing seeds. They move slowly across the desert, relying on rodent middlemen to collect their seeds and cache them in nearby patches of dirt. And they depend on a single pollinator, the aeronautically challenged yucca moth. All these factors make it difficult for the trees to escape to higher and cooler climes.
In 2015, the nonprofit conservation group WildEarth Guardians petitioned the US Fish and Wildlife Service to list the Joshua tree under the Endangered Species Act. The group was supposed to receive a response about the next step in the process six months ago. It is still waiting.
On top of a bureau in my bedroom I keep a small amber bottle filled with what look like miniature guitar picks, each as smooth as a river pebble and as black as charcoal — the seeds of a Joshua tree. I got them many years ago on a family vacation in Southern California. I wish I could say I see the bottle as an ark, but it seems more like a reliquary. In this vial sit the parched remains of yet another species soon to be extinguished in pursuit of ourselves. Ferris Jabr is a science writer.