California's Desert Sands

Kelso Dunes in the Mojave National Preserve | Chris Clarke photo

There's a lot more to the California deserts than blowing sand, but you wouldn't have known it if you were driving out of Palm Springs with me this past weekend. Indian Canyon Drive, a main northerly route out of town, crosses the sandy Whitewater River wash just in the exact spot where the winds funnel down out of San Gorgonio Pass. The city usually closes the road when the winds pick up but for some reason Sunday they were a bit late in doing so.

I found myself in a line of cars buffeted by the wind, the west sides of each vehicle effectively sandblasted. A few SUVs drove up on the shoulder, using the rest of us as a windbreak. Tempers flared. The guy directly in front of me, driving an economy sedan with Georgia plates, refused to let one of the shoulder SUVs merge back onto pavement. I nearly had a front-row seat for a classic act of Southern California road rage, except that when the sedan driver got out of his car to shake his fist at the SUV's occupants the wind caught his hat and hurled it several hundred feet to the east. Eventually the traffic ebbed and we all headed off to get our air filters changed.

Sandstorms like this Sunday's are fleeting events generally lasting a day or two at most, but their cumulative effect on the desert is dramatic. Each grain of sand moves only a short distance at a time, but the overall result is that great rivers of airborne sand flow across the deserts, much of it ending up in one of California's many desert sand dunes.

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Where these rivers of sand follow predictable corridors, there you can find plants and animals that have evolved adaptations that allow them to survive a sandy environment. This is more difficult than you might think. Sand is a relatively inhospitable environment; blazing hot and dry in summer, shifting unpredictably under winter winds, hard to sink reliable roots into and hard to walk across. The best-known example of a sand-adapted animal in the California deserts is likely the sidewinder, a small rattlesnake with a unique way of moving across hot sand:

Note how only a small amount of the snake's body touches the hot sand at any one moment, a strategy that may seem oddly familiar to people who've walked barefoot on hot beaches.

Fringe-toed lizards, of which California hosts three species, are also well-adapted for life in the sand, with their eponymous fringed toes that offer a bit of extra stability and traction the way snowshoes do in loose powder. They are shy of people and can reach speeds of up to twenty miles an hour within a few seconds of a standing start, which is why photos of fringe-toed lizards often look pretty much like this one:

Coachella Valley fringe-toed lizard

in which the lizard -- here, a Coachella Valley fringe-toed, listed under the Federal Endangered Species Act (ESA) as a Threatened species -- clearly enjoys a temporary false sense of security beneath a shelter of branches. Fringe-toeds are in the same family as horned lizards, and the Salton Sink's flat-tailed horned lizard shares both the fringe-toed's predilection for sand and the relevant podiatric adaptations.

If you're a plant, a sand dune offers a unique set of challenges and opportunities. After a good soaking rainstorm -- which do actually happen in the desert, despite what you might think -- a dune can hold a fair amount of water stuck to its sand grains a couple feet below the dessicated surface. Sand also provides very little resistance to root growth. So if you're a plant that can put out a whole lot of roots in a wet season, then endure a year or two with little rain at all, you might just find a sand dune a salubrious environment in which to germinate, grow, and set seeds.

California's dunes are home to a number of rare plants, some of them found only in their home dunes. The Eureka Sand Dunes -- at 700 feet California's tallest dunes, in the Eureka Valley northwest of Death Valley -- are home to three such plant species. The Shining milkvetch, Eureka dune grass and Eureka Dunes evening primrose grow there and nowhere else in the world. The grass and primrose have been listed under the ESA, as has the Peirson's milkvetch from the Algodones Dunes 300 miles south in Imperial County, which is just one of a host of rare plants in that dune system.

Peirson's milkvetch | BLM photo

You wouldn't think that something like sand would be vulnerable to human activity, but the great system of sand rivers and dunes actually faces significant threats from the way we behave. The above-mentioned Peirson's milkvetch is listed as threatened, in part, due to pressure on its habitat from off-road vehicles in the Algodones Dunes. Quite a lot of California's desert sand has been given over to off-roaders' play. Along with Algodones there's also the Dumont Dunes near Death Valley, the Heber Dunes near El Centro, and the sandy expanse around Rasor Road west of the Mojave National Preserve.

There are also more subtle threats to the desert's sand ecosystems. Development in valleys that function as what the ecologists call "sand transport corridors" can interrupt the flow of sand from one place to the next, the end result being long-term decline of dune habitats. The Coachella Valley fringe-toed lizard originally ranged over about 270 square miles of sandy habitat in the valley; that range has shrunk to 50 square miles or so, but -- according to the US Fish and Wildlife Service -- only about 40 percent of that remaining habitat still gets new sand blown onto it, raising fears of habitat degradation over the next few decades. It's not just the fringe-toed lizard that stands to lose. The endangered Coachella Valley milk vetch, Coachella Valley round-tailed ground squirrel, Coachella Valley giant sand treader cricket, and the Coachella Valley Jerusalem cricket also rely on what FWS refers to as "blowsand habitat" -- habitat maintained by the same wind-driven sand that battered my 20-year-old Jeep this weekend.

You don't have to damage California's desert sand dunes with an off-road vehicle to enjoy them. There are dunes in a number of places throughout the desert that have been closed to off-road vehicles, but which can be readily visited with a good street vehicle and a little bit of walking. The Kelso Dunes in the Mojave National Preserve are a great example, only four miles off paved Kelbaker Road via a well-maintained washboard. You can climb to the dunes' ridgeline and look out across the "Devil's Playground," the terminus of all the sand transported along the Mojave River watershed. In Death Valley, the Mesquite Flat dunes by Stovepipe Wells are accessible by paved road and less than two miles from a hotel. They offer some wonderful hiking.

Or you could just come visit Palm Springs on a windy day and see the whole ecosystem in action. Be sure to roll your windows up, hang on to your hat, and if you see a guy in an XXL Hawai'ian shirt driving a Tercel with Georgia plates don't try to cut him off. He means business.

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