DesertBlog

Climate change threat to Joshua trees gets more press

The Riverside Press Enterprise reported Saturday on the increasingly widespread concern that in a century or so, Joshua Tree National Park’s namesake species might not grow there anymore.

The ancient plants are dying in the park, the southern-most boundary of their limited growing region, scientists say. Already finicky reproducers, Joshua trees are the victim of global warming and its symptoms — including fire and drought — plus pollution and the proliferation of non-native plants. Experts expect the Joshuas to vanish entirely from the southern half of the state within a century.

The article is erratic in quality. The reporter, Janet Zimmerman, says in one paragraph that Joshua trees are very likely to be wiped out in southern California; a few paragraphs down she quotes the Palm Springs Desert Museum’s former natural history curator Jim Cornett as saying the trees are reproducing well, and otherwise thriving, in southern California’s Mojave National Preserve.

There’s also a weird insinuation that saguaros are spreading throughout the southern range of the Joshua tree, which isn’t so: Californian saguaros are still restricted to the a tiny part of the easternmost tip of the Whipple Mountains across the river from Parker, Arizona, and saguaros are every bit as threatened by climate change, in the long run, as are Joshua trees, due to invasive-plant-fueled wildfires and threats to the species’ pollinators.

The article is good press for the beleaguered trees nonetheless, and touches on the main issues placing the species in peril, fire and drought chief among them. Zimmerman mentions assisted migration and revegetation of burned areas with blackbrush, Coleogyne, which acts as a nurse plant for Joshua tree seedlings, keeping them protected from marauding jackrabbits. It may be that the scientific models she mentions are too optimistic — I reported on that here last year — but whatever the caveats, the Press-Enterprise piece is worth checking out.