When I talk to people from other parts of the country about living in a “desert”, the first thing they usually mention is how hot they imagine it would be. We Mojave dwellers really do know better. I enjoy telling people that the biggest desert on earth is Antarctica. That’s what I call Xeriscape! We think we have limited landscape options!
No, heat is definitely not the definitive element of a desert. Lack of precipitation makes a desert. Lack of water makes the air and soil dry, which of course limits the amount and types of vegetation that can naturally survive here. Our water supply is considerably reduced, which is visible in the “bathtub ring” around the perimeter of Lake Mead. Drought – desert –We’ll always need to conserve water.
All that aside, another aspect of a desert climate that many people don’t think about is the astonishing wind that regularly sweeps over the mountains and down, across the landscape. Since we have relatively little plant material, and not much in terms of big plants – not too many large native trees here in the Mojave – there’s not much to hold the soil in place. The paltry fertility of southern Nevada soils gets even lower with wind erosion. The desert is actually shaped by the wind to some degree – look at the dunes in areas where the soils are sandy. And all around here – at Red Rock, in certain spots along I-15, you can see rock faces with horizontal etching. That shallow scarring results from windstorms carrying tiny rocks, whipping them across the surface of larger ones.
Have you ever been told that our air quality will improve as soon as we get a few days of good, fierce wind?
The first time I heard that, I was baffled, but it does seem to happen – a storm blows up, carrying our dust and our pollution to wherever – maybe Utah?
So here we are, living in a place with little water and big winds. The wind stirs up, creating the soils and removing them, shaping the rocks, and drying out the already dry air. It just makes sense that a force this strong is going to affect the plants that are exposed to it. Not only by making our desert even more arid. I don’t want to sound as if I’m minimizing the terrific adaptations you find on desert plants. Things like cactus spines, downy coverings on lots of leaves and waxy coats on others – all of these help plants conserve water despite the dry air – and those are phenomenal. But that’s not the only way plants are affected by the remarkable winds of the desert.
Some plants’ll anchor themselves really securely into the ground – like the deep taproot of sagebrush, which allows it to access water far below the soil surface. In fact, one of the ways that you can keep a plant from being thrown about by the wind is to water it deeply whenever you water it – not often, but deep; encourage the roots to grow down.
A lot of plants don’t try to tough it out against the wind, though. So many flowers are wind pollinated. Some plants produce seeds that look as if they have wings to spread and fly away. Desert willow and saltbush rely on the wind to propagate. Now that dandelion’s a common weed locally, everyone’s going to get to see how those seeds blow in the wind. A member of Nevada’s invasive weed list, green fountain grass, does the same thing.
But some plants are even more extreme. Take a look at tumbleweed. This is a plant that literally goes whatever way the wind is blowing. I was so disappointed when I discovered that it wasn’t a symbol of the old west at all – it’s Russian thistle! It was less of a disappointment than a surprise.
I’ve been pulling it out all over the place. Nasty, spiky stuff. What happens with Russian thistle is – after it produces flowers and seeds, the whole plant dries out. It’s a big shrubby thing attached to the earth by a thin stalk that breaks, and the dead plant tumbles away with its dry flowers and its gazillions of seeds. As the tumbleweed goes tumbling along on the breeze, it spreads the seeds everywhere – very efficient.
Blowing in the wind. It’s more than just a folksong.
So, what makes a desert? Maybe hot, maybe not, always dry, but those winds…
For KNPR’s Desert Bloom, this is Dr. Angela O’Callaghan of the University of Nevada Cooperative Extension. Stay safe and healthy.