It started with a 2011 study that indicated by the turn of the century there would be no more Joshua trees in the national park named after the iconic desert plant.

And likely none in California.

“I was shocked when the study came out. I wanted to look at the details and change the scale,” said Cameron Barrows, a research ecologist for the UC Riverside Center for Conservation Biology in Palm Desert.

The large scale of the study by Kenneth Cole, a climate scientist for the federal government’s Colorado Plateau Research Station in Flagstaff, Arizona, missed many of the geological nuances of Joshua Tree National Park and elsewhere, according to Barrows, which could ultimately mean survival for the Joshua tree species.

Barrows coordinates the center’s Desert Studies Initiative.

Doing his own modeling, which took a detailed look at the geography of Joshua Tree National Park, Barrows said that going into 2100, this 13,000-year-old desert plant species may survive — at the higher elevations of Joshua Tree National Park and along north-facing slopes and some canyon areas.

Scientists working with Barrows, along with helpers from the National Park Service and other agencies, at a workshop earlier this month trained a team of about 40 “citizen-scientists” to help gauge the health of Joshua trees across some of the study areas.

The volunteers surveyed and measured the heights of Joshua trees, coupling the measurements with GPS locations, and a description of other plants nearby and likely offspring of the same parent.

The Nov.6 survey showed good health among a range of age groups for the Joshua trees in the study area.


Although Barrows presents a more optimistic view on the future of Joshua trees than does Cole, there are still problems, he said.

In addition to the warmer winters and summers, there’s air pollution depositing nitrates on the soil, according to Barrows.

That soil enrichment will transform portions of the now largely barren desert into grasslands. The location where the grasses will thrive coincides with the prime habitat for these surviving Joshua trees.

With grasses come forest fires, and the Joshua tree is not a plant that has adapted to fire. Recovery will be difficult, Barrows said, and certainly not helped by the fact that it can take 70 years for a Joshuatree to produce offspring.


What we know as Joshua trees weren’t always called that.

In the late 1880s, yucca palm was the popular name for the tree, according to Chris Clarke, a Joshua Tree resident who is working on a book on the trees based on his decades of research. Another name was tree yucca.

The plant is not in the palm family, but that didn’t matter when Palmdale was named after the iconic plant, Clarke said, during a presentation to the citizen-scientist group the day before their field experience.

Clarke was among several speakers to make presentations to the citizen-scientist group at the Black Rock Ranger Station.

The name Joshua tree really started to take off at the beginning of the 20th century, although the name tree yucca persisted in scientific literature into the early 1930s, Clarke said.

There was a brief effort to make paper from yucca plants in the 1880s, when the Atlantic and Pacific Pulp Co. stripped off about 5,000 acres’ worth of Joshua trees in an unsuccessful effort to make paper from them.

“If you ever wondered why there are no Joshua trees around Acton (in Los Angeles County), that’s the reason,” Clarke said, adding that the Joshua trees never rebounded from that failed business venture.

There are two Joshua tree varieties. One is found in the Mojave and is more commonly recognized. The other is less treelike and more like a bush and found in the Colorado Desert.

They live together only in a portion of the Nevada desert, near the so-called Area 51, about 100 miles outside of Las Vegas, said Chris Smith, who has taught evolutionary biology at Willamette University in Salem, Oregon, and led scientific expeditions in the U.S. and Mexico deserts.

Smith said there is evidence that the two species are interbreeding.

With global warming, the Joshua tree species will likely migrate north over time, Smith said. And it might be that one of the two varieties, or the hybrid, will become the dominant plant.

Clarke, Barrows and Smith were among several speakers at the workshop, which was a partnership between the Desert Institute, the California Native Plant Society, Joshua Tree Genome Project, UC Riverside Center for Conservation Biology, UC Riverside Sweeney Granite Mountains Research Center, USGS Western Ecological Research Center and Joshua Tree National Park.

The Rose Foundation provided funding for the event.

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