S4E10: 3 Ways the Desert Improves Your Life

UNCORRECTED TRANSCRIPT

0:00:01 - (Chris Clarke): 90 miles from Needles, the Desert Protection Podcast is made possible by listeners just like you. If you want to help us out, you can go to 90 miles from needles.com donate or text needles to 53555 think the deserts are barren wastelands. It's time for 90 miles from needles the Desert Protection Podcast. Thank you, Joe, and welcome to this episode of 90 Miles from Needles the Desert Protection Podcast.
0:00:51 - (Chris Clarke): I'm your host, Chris Clarke. And today we have three counterintuitive, I guess, science facts about the desert that might change the way you look at the desert. But first, this is the part of the show where I generally start out by thanking people who have become new donors in the last week, or at least since the last episode. And we don't have any. So I'll just say 90 miles from needles.com donate.
0:01:25 - (Chris Clarke): We could use your help. One of the things I like best about the desert is that I just keep learning things about what's going on here, about the other things that live here. And the more I learn, the more I realize the more I have to learn. A really good example of this came up this past couple of days, and my friend Luke, who's been on the podcast before, posted a photo of doing some work with tortoises in which the wild desert tortoise that he was working with had some hitchhikers on it.
0:02:06 - (Chris Clarke): In the photo he took and put up on Instagram, there were half a dozen or so ticks, little tiny pale ticks just sort of hanging out on the tortoise's shell. And I was briefly surprised by this because it seemed a little counterintuitive. And you know, my brain knows that tortoise shells have nerve endings and blood vessels and all that kind of stuff. I know you can cause a tortoise significant pain if you do damage to its shell.
0:02:35 - (Chris Clarke): I think a lot of us have the impression of the tortoise's shell as this inert protective shield, like a army helmet or something like that. But a tortoise shell is not just armor. It's part of the tortoise's way of sensing the world. And so of course, with the blood vessels there, especially in a place like the Mojave Desert where any kind of water based fluid is extremely valuable, there are going to be ticks and almost certainly other parasites that are after a little bit of tortoise blood.
0:03:08 - (Chris Clarke): And this is made even more complicated given that tortoises hang out in places that some kind of ticks really like to be holes in the ground. The ticks that like to live in holes in the ground tend to be soft bodied ticks. And the tortoise in the photo did indeed have soft ticks. Catching a ride. Now, when you think of ticks, you might think of those little pesky things that crawl up your leg. Find a nice sheltered spot sometimes under your belt. It's a really common place.
0:03:37 - (Chris Clarke): They stick their head into your skin and they start drinking blood and they swell up and they can be there for hours and hours just hanging out, living off your blood. Soft ticks are different, especially in the genus Ornithodoros. Soft ticks, at least as far as they interact with humans, are really small under really fast feeders. Generally less than an hour is the amount of time they take to get their blood meal, and then they're gone. And if you're bitten by a soft tick, especially in the genus Ornithodoros, you might not even know it until a week later if you are supremely unlucky.
0:04:14 - (Chris Clarke): The spirochete bacteria and genus Borrelia that soft ticks often carry in their own blood causes an infection called tick borne relapsing fever. I had heard of tick borne relapsing fever and just the name was enough to cause me to not ever want to get it. But I never really looked into it until the last couple days when I started looking into the ecology of ticks that are found on desert tortoises.
0:04:41 - (Chris Clarke): And here's what Wikipedia has to say. Good starting place. Along with fever, which is right there in the name, patients may experience an incredible range of non specific symptoms. The clinical features of relapsing fever may include chills, nausea, headache, muscle and joint aches, vomiting, lethargy, anemia, facial paralysis, anorexia, dry cough, light sensitivity, neck pain, eye pain, confusion, dizziness, myocarditis, dermatitis, brain infection, lymphoid hyperplasia, and complications of pregnancy, including miscarriage, premature birth and neonatal death.
0:05:23 - (Chris Clarke): But the fever is what the thing is named after. And relapsing fever means that you get better and then you get worse, and then you get better and then you get worse. Generally, this disease incubates for a week after the bite, and then after that week goes by around three days of high fever, along with all those other symptoms, culminating in a crisis in which the patient's fever could spike as high as 106.7 degrees Fahrenheit, an extremely dangerous fever for about three hours or so, and then the patient apparently recovers.
0:06:03 - (Chris Clarke): And another week goes by, and then another horrible long weekend of really unpleasant symptoms passes and without treatment, assuming you survive, the fever is about four of those cycles a week off, a long weekend on, you'll recover a lot faster if you get to the doctor and take some antibiotics. Now the reason for that interesting kind of on again, off again nature of the disease is that the spirochetes, the little helical shaped bacteria that cause tick borne relapsing fever, basically camouflage themselves.
0:06:41 - (Chris Clarke): Our immune systems react to the proteins on the outside of the spirochete cells and start triggering antibody production. After three days, those antibodies are prevalent enough to knock back the number of bacteria in your system and you get that week long period of feeling better. But the spirochetes are up to no good and they change the proteins that they have on the outside of their cells. In the words of one researcher who has looked into the interrelationships between Borrelia bacteria, ticks and wildlife, including tortoises. As antibodies in the human immune system increase for one variable, major protein, another variable, major protein, unrecognized by the initial antibody response, will begin to increase, causing another fever period and forcing the immune system to build different antibodies against this different protein.
0:07:38 - (Chris Clarke): 46 to 80% of untreated infected patients required admission of hospitals due to acute respiratory distress. And so, like the other really popular tick borne diseases, namely Lyme disease and Rocky Mountain Spotted Fever, tick borne relapsing fever is something you really want to not ever get. But as it turns out, desert tortoises are doing us a favor here. In 2022, in her doctoral thesis, Molly June Bechtel at Northern Arizona University looked into the ecology of ticks and desert tortoises.
0:08:12 - (Chris Clarke): Her dissertation was entitled Ticks, Tortoises and Tick Borne Relapsing Fever in Mojave Desert Tortoise Habitat. We'll put a link to that in the show. Notes it is open access. Here's the abstract paragraph of that dissertation. The argacid ticks Ornithodorus parkeri and Ornithodorus turicata occur throughout the Mojave Desert and are frequently observed on Mojave Desert tortoises. These ticks harbor and transmit tick borne relapsing fever group Borrelia, resulting in tick borne relapsing fever in people.
0:08:45 - (Chris Clarke): Tick borne relapsing fever group Borrelia is endemic in the Western U.S. however, it's typically associated with a bite of an infected Ornithodoros hermseye tick found in habitats at high elevations above 1500ft and continues to say, despite the risk of contracting tick borne relapsing fever in desert tortoise habitat, there is up until now, very little research examining the relationships between those soft ticks and the desert tortoise.
0:09:14 - (Chris Clarke): Bechtel basically suggests that tick borne relapsing fever is probably underreported and might be a larger risk to human health than previously understood. And she points out that wildlife biologists, owners of pet tortoises, or other people that have opportunities to interact with tortoises or their burrows are at higher risk for contracting tick borne relapsing fever. And desert tortoises that spend more time in burrows are more likely to be infested with ticks.
0:09:43 - (Chris Clarke): All that said, Bechtel also reports that ticks found in the Mojave Desert have a pretty low incidence of the Borrelia bacterium. Bechtel collected a total of 1165 ticks off of tortoises found at a bunch of different study sites. Ornithodorus parkeri and Ornithodorus turicata were the two species that made up that 1165. And the surprising thing was that of those 1165 ticks tested, only 22 of them had the Borrelia bacterium that causes tick borne relapsing fever.
0:10:18 - (Chris Clarke): That's 1.8%. One in 53 ticks were carrying around this dangerous bacterium. And that's a really low number compared to tick populations in other places. And it indicated that something might be suppressing the prevalence of this bacterium in soft ticks that were found in association with desert tortoises. Now, they don't just feed off of tortoises. There are any number of animals, reptiles, mammals, things like kit foxes and rodents and rabbits and such, that these soft ticks will parasitize, including humans.
0:10:56 - (Chris Clarke): And as I was making my way through Bechtel's thesis, something occurred to me that obviously occurred to Bechtel as well, I found out as I read further. But the thing that occurred to me was that the western fence lizard found along the California coast has been documented to have proteins in its blood that kill a related species of bacterium, Borrelia burgdorfi, which is responsible for Lyme disease.
0:11:21 - (Chris Clarke): This protein that the lizards have in their blood gets sucked into the tick. The tick gets its meal and can develop, but it is cleared of the Borrelia bacteria that cause Lyme disease. And my immediate thought was maybe tortoises have something similar going on in their blood. Maybe tortoises can kill Borrelia bacteria that cause tick borne relapsing fever. And the same thing occurred to Bechtel. So Bechtel took a sample of live Borrelia spirochetes, the bacteria that caused this horrible disease, and did a little experiment called an assay, in which she exposed the spirochetes to desert tortoise plasma taken from very small samples of desert tortoise blood.
0:12:03 - (Chris Clarke): And she found that those bacteria do not survive in desert tortoise blood. Now, there's a growing sense among people that study diseases in wildlife populations that for a lot of tick borne diseases, reptiles are what are called incompetent hosts, which is sort of a misleading phrasing to the layperson. An incompetent host is not a good host for the bacteria that cause tick borne diseases, which means that those incompetent hosts are better able to survive a tick bite.
0:12:37 - (Chris Clarke): And so Bechtel proposed a hypothesis that a similar factor may be present in the blood of desert tortoises. Here's how Bechtel put it. Our results suggest that Mojave desert tortoises have a borreliacidal factor in their plasma that may be related to complement mediated immunity. The tortoise blood killed 95% of the spirochetes. Meanwhile, bacteria that were introduced into mammal blood as a control did just fine.
0:13:06 - (Chris Clarke): So while people that handle desert tortoises are more at risk than most of us for contracting tick borne relapsing fever, the tortoises are kind of looking out for them. The tortoises are reducing that risk of contracting that disease by about 95%. This is a cool science fact, but it's got some conservation implications too. The desert tortoise is critically endangered, and one of the reasons it's critically endangered is that people are moving into its habitat and doing things. Building solar facilities, building landfills, parking lots, new suburbs of desert cities, subsidizing ravens that eat tortoise babies.
0:13:48 - (Chris Clarke): The tortoise is basically on the verge of extinction in the wild. It's not certain yet. You can check out our episode with Luke Basulto, the tortoise tick photographer I mentioned, and Tim Shields. There's a link in the show notes, and they talked about what kinds of things people are thinking about and doing to save the tortoises. But this is another reason to save the tortoise, because if you combine losing the tortoises with people moving into the area and the tortoises burrows, which are full of ticks, suddenly being inhabited by rats and mice and rabbits, which do not reduce the prevalence of tick borne relapsing fever, Borrelia bacteria, then you get a higher prevalence of tick borne relapsing fever cases in the human population.
0:14:30 - (Chris Clarke): So next time you're lucky enough to see a desert tortoise in the wild, you might want to offer some thanks. Because one desert tortoise, through the thing in its blood, whatever it is, still undiscovered, that acts as a bactericide and reduces the prevalence of tick borne relapsing fever. One desert tortoise has done more for human public health than an entire RFK junior. Not that that's a particularly high did you know that deserts suck carbon out of the atmosphere and store it for periods of time that could be measured on the geological scale.
0:15:26 - (Chris Clarke): That's a little counterintuitive for some folks. When we think about ecosystems locking up carbon, taking it out of the atmosphere and turning it into something that doesn't threaten our climate, we usually think of that in terms of living biomass and tree trunks and soil organic matter and things like that. And so it's almost understandable that when desert protection activists and the soil scientists that study the desert started talking about the deserts as a significant reservoir of stored carbon that was being kept out of the atmosphere, there were quite a number of folks that just didn't believe it.
0:16:04 - (Chris Clarke): You can see the bare soil all over the place. There's way less biomass, at least above ground, in most desert ecosystems than in a typical east coast deciduous forest with maples and oaks and things, or Pacific Northwest conifer forest with 200 foot tall pine trees, or even some grasslands and meadows. They all look like they have more biomass than the desert. But there's more than one way to store carbon. Biomass isn't the only way.
0:16:35 - (Chris Clarke): And storing carbon in the soil is what happens in the desert. I mean, there are plants and animals that live in the desert and they have carbon in them and they're walking around or photosynthesizing above ground. But most carbon sequestration in the desert is underground. There are a couple of ways that this happens. First off, in deserts and for that matter, everywhere else, the plants grow. Plants have roots in the soil and they use those roots to pump carbon dioxide into the soil.
0:17:06 - (Chris Clarke): How does that work? Well, the above ground parts of plants, if they're green, they photosynthesize. They take in carbon dioxide and use energy from sunlight to turn it into sugar by combining it with water. That's what photosynthesis is. And as a waste product, fortunately for us, they breathe out oxygen, which we need to survive. So go us. That's true of the photosynthesizing part of the plant, which is generally the leaves, but also in a lot of species, especially in the desert, stems and trunks are green and are turning CO2, water, and sunlight into sugar.
0:17:46 - (Chris Clarke): If you're photosynthesizing during the day, you're releasing oxygen into the atmosphere. Now, that changes at night. Plant cells have metabolisms just like the rest of us. They have to burn food in order to get the energy to live and reproduce and all that kind of stuff. They basically burn sugars for energy, and that creates carbon dioxide that gets released into the atmosphere at night. So they photosynthesize during the day, and at night they respire just like we do.
0:18:14 - (Chris Clarke): That's the above ground portion of the plant. Below ground, where light can't get to. The plant roots are not exposed to light, and so they cannot photosynthesize. They don't take in carbon dioxide. What they do is they get sugars from the parts of the plant that are photosynthesizing and they burn that to stay alive. And as a result, they release carbon dioxide into the soil. So during the day at least, you have plants taking in carbon dioxide through their leaves and emitting it into the soil through the roots.
0:18:49 - (Chris Clarke): Now, a lot of that carbon dioxide will just sort of diffuse back through the soil up into the atmosphere. Doesn't take a whole lot of time for carbon dioxide that's like 2 inches down in really loose soil to just come back up and change our climate again. This is not complete sequestration of every bit of carbon dioxide that gets taken in. But keep this in mind. Some roots go pretty deep in the desert, a dozen feet or so. Mesquite roots, for instance. Honey mesquite can get down a couple hundred feet.
0:19:18 - (Chris Clarke): It's going to take a While for that CO2 to diffuse back up into the atmosphere. Some of it will stay down there. It'll react with other minerals in the soil, like calcium. It'll form calcium carbonate here and there. It's one way that plants in the desert can sequester carbon in the soil. There are other ways, too. 95% of all plant families studied have relationships with what you will probably most likely know as mycorrhizal fungi.
0:19:45 - (Chris Clarke): This is a symbiotic relationship in which little fungal threads called mycelia will connect up with roots. Some kinds will get into the cells of the plant. Others will just sort of nuzzle up to the cells. They'll cuddle with the root cells. Fungi are really good at extracting minerals from the soil and from whatever organic matter is in the soil and water is a mineral, and they're really good at extracting that. And they will share that water and other minerals with the plants that they're connected to.
0:20:16 - (Chris Clarke): The plants also share sugars that they build through photosynthesis. Everybody's happy now. One kind of mycorrhizal fungus called arbuscular mycorrhizae, which is one set of the mycorrhizal fungi that actually penetrate the plant's root cells. Arbuscular mycorrhizae are widely considered to secrete a substance called glomalin that's a glycoprotein. It's a protein that's part sugar that becomes important. We won't get into the weeds just yet, but arbuscular mycorrhizae produce this protein in the soil and in the roots of the plants that they merge with. And glomalin is kind of a gluey thing. It's very sticky. It's very strong, very persistent.
0:20:59 - (Chris Clarke): It binds together really firmly, either to itself or to soil particles. And it's there basically as a way to keep water and nutrients from just leaking out of the fungal cells into the soil and being lost. Glomalin is a glycoprotein. A glycoprotein is basically a long chain of sugar. The technical term is oligosaccharides. And on that long chain of sugar, there are amino acids attached to side chains.
0:21:24 - (Chris Clarke): The oligosaccharides in glomalin are what's really important here, because that long chain Sugar is about 40% carbon, probably more, actually, with simple sugars. If you have about 100 pounds of table sugar, that's around 40 pounds of carbon. With long chain sugars like oligosaccharides that have fewer hydrogens and oxygens per carbon, that percentage of carbon gets a lot higher. So glomalin that is secreted into the soil contains a whole bunch of carbon, and it's stable. It doesn't just diffuse up into the atmosphere and get lost.
0:21:58 - (Chris Clarke): And I should say that there are, just to be precise, a few different related things that are often called glomalin for short. One is the actual hypothetical glomalin protein, which, as of research papers available on Google Scholar after 2024, has not been isolated yet. And then there's something is also called glomalin related soil protein, or grsp, which has been found unlike glomelan proper. And it's complicated. Its makeup depends on what's nearby.
0:22:31 - (Chris Clarke): You can have metal ions or organic chemicals or humic acid from decaying vegetative matter. All this different kind of stuff. But the salient fact here, aside from the fact that glomalin or its related soil proteins acted as a really good glue for soil particles, it's generally thought that about a quarter of total soil carbon worldwide, in most different soil ecosystems, is glomalin or glomalin related soil proteins.
0:22:57 - (Chris Clarke): Twenty years or so ago, the U.S. department of Agriculture hypothesized that as much of a third of the world's soil carbon is glomalin. Glomalin is extremely persistent. It improves the stability of soil aggregates, meaning it clumps particles together. And that provides better water penetration and aeration in the soil, which is better for plants, doesn't break down, so that stored carbon will stay there for years and years and years.
0:23:24 - (Chris Clarke): The third way that soil becomes a repository for stored carbon will come as little surprise to people that have tried to dig holes in the desert. It's also related to mycorrhizal fungi and their partnership with plants. With many, many, many different species of plants and mycorrhizal fungi, the point of connection between the fungus and the plant is the site of creation of calcium carbonate crystals.
0:23:50 - (Chris Clarke): The plant will pump out a little bit of CO2 from its living root cells. That CO2 comes into contact with calcium ions being transported by the mycorrhizal fungi, and they form little crystals of calcium carbonate. Now, in case you're wondering whether that's an unusual thing, keep in mind that right now you are creating calcium carbonate in much the same way, not using plant and fungus cells, but building your bones.
0:24:18 - (Chris Clarke): All different kinds of animals can take calcium and CO2 and turn them into calcium carbonate, including oysters and clams and barnacles and you and me. In the desert, those little crystals of calcium carbonate stick around. In places where there are larger rainstorms, you have rainwater. Dissolving CO2 as it goes through the atmosphere becomes a very weak solution of carbonic acid, which could conceivably dissolve that calcium carbonate and turn it back into calcium and CO2. So in a lot of places that get more rainfall, you don't get quite that buildup of calcium carbonate. But in the desert, because we don't get that much rain, and when we get a lot of rain all at once, it generally runs off, that calcium carbonate just builds up and builds up and builds up, and we call it caliche.
0:25:15 - (Chris Clarke): It's basically limestone in the desert. And the partnership between mycorrhizal fungi and plant roots is responsible for a huge proportion of the calcium carbonate stor stored in the desert. And you have seen this if you have spent any time in the desert looking anywhere where there's a dry wash. If you walk up that dry wash and there's cut banks on either side, you will see little shelves of white or pale brown rock that resist erosion and they get undercut.
0:25:46 - (Chris Clarke): They're just like little bookshelves sticking out in the middle of the wash. That's caliche, that is limestone. That is sequestered carbon. When it's exposed, like in a dry wash, it does tend to weather and release carbon into the atmosphere. But for every little bit you see exposed in a dry wash, there are hundreds of thousands of tons nearby, buried in the soil, safe from being returned to the atmosphere.
0:26:12 - (Chris Clarke): There are a few other ways that deserts will work as sinks for carbon dioxide. There are biocrusts, things like cryptobiotic soil that do hold some carbon in their living tissues, including the little tendrils that anchor them to the ground. Bunch of other ways, but caliche is really the main thing. According to a 2023 paper called Hidden in California's native habitats are valuable carbon sinks. And we'll link to that in the show notes.
0:26:40 - (Chris Clarke): The United States deserts are considered to sequester 50 teragrams of carbon every year. That's more than 55 million tons of carbon sequestered every year. That is approximately the output of 11 million private cars taken out of the atmosphere and stored in a stable form every year. And that net carbon is stored for as long as the desert is left intact, as long as only natural forces are allowed to uncover a little bit here and there through the flash floods. As long as we leave the desert alone, it stores a whole lot of carbon for us.
0:27:18 - (Chris Clarke): Which is ironic because people are turning to the desert as a place to save us from climate change by destroying that ecosystem that's sequestering carbon and replacing it with short lived renewable energy plants. To my knowledge, nobody has looked into this. We may actually be making climate change worse in the long term by destroying the desert to put in solar power. The desert's trying to do its best to help us with climate change as it is.
0:27:46 - (Chris Clarke): Maybe we could just let it do what it wants. Spend enough time walking around in the desert and you will eventually find broad, more or less flat expanses of ground completely covered with a blanket of small rounded rocks. At first glance, the ground cover in these spots may seem unremarkable, as if someone had just spread a layer of gravel over a dead surface. Look a little closer, though, and surprises emerge.
0:28:28 - (Chris Clarke): The stones don't look randomly scattered. For one thing, their corners are often tucked neatly into hollows of the stones adjacent to them, fitted together so closely that sometimes you might have trouble seeing a space between them. Pick up one of those stones and more surprises come to light. Though there are deposits of gravel hundreds of feet thick in the desert, more often than not, the stony pavement you're standing on will turn out to be no more than one layer of stones thick, a brittle protective armor on a thick deposit of sand and silt.
0:29:02 - (Chris Clarke): I put pavement in quotes there, as if I had come up with a metaphor on my own. But that's what desert soil scientists actually call these layers of desert pavement. Desert pavement covers hundreds of square miles of the desert. Dry lakes and sand dunes capture the popular imagination a lot more. But I'd venture to guess that they cover only a fraction of the area that desert pavement does. And once you start noticing desert pavement, you'll see it almost everywhere you go, at least in areas where large amounts of sediment have tumbled down off the slopes of stony mountains.
0:29:36 - (Chris Clarke): But this odd arrangement of soil, heavy stones, and a thin, nearly complete layer atop deep, fine sediment clearly didn't just fall into place intact, any more than flour, sugar, and cocoa powder dumped into a bowl land in the form of a layer cake. If it was up to gravity alone, desert soil would generally be composed of a random mix of particles, ranging in size from dust specks to boulders the size of a 1967 VW Microbus, sorted somewhat by the action of flash floods.
0:30:08 - (Chris Clarke): Something clearly arranges the stones, sand, and silt into a desert pavement soil profile. But what? For a long time, people assumed that desert pavement was what was left over after incessant wind, of which there is certainly a great deal in the desert, blew off the silt and sand and very fine gravel. It takes a strong wind to move rocks larger than an inch in diameter, so rocks that size and larger would remain jostled around a little with each gust until they nestled down into a stable interlocking pattern geologists call wind powered erosion deflation.
0:30:45 - (Chris Clarke): And you can still find references to desert pavement here and there as deflation. Armor sheet floods, in which water does much the same thing, have also been proposed as the force behind desert pavement's creation. And both wind and water certainly play a role in the creation of similar soil pavements in former glacial till in the Midwest or coastal prairies farther west in California. And geologists are satisfied that in some places in the Desert wind and water are all we need to explain the existence of desert pavements.
0:31:17 - (Chris Clarke): But wind and water don't work as explanations everywhere. There are a lot of places in the desert where desert pavement coexists with cryptobiotic soil crusts, which hold soil against the ravages of wind and gentle rain, keeping the dust and sand from blowing or washing away. Often enough, the soil beneath the desert pavement won't have any stones in it at all. Which means the pavement wasn't solely formed by removing finer sediments from the very top layer.
0:31:45 - (Chris Clarke): Instead, it means that some process must have brought that thin layer of stones to the top. Frost, heave, salt crystal formation and the action of soil fungi have all been suggested as mechanisms for moving stones to the surface, all with some plausibility. Now, about 15 years ago or so, I read a blog post by California geologist Andrew Alden in which he pointed out that a swath of desert pavement in the Mojave Preserve raises the explanatory stakes even higher.
0:32:18 - (Chris Clarke): Just west of Sema Dome and the preserve are some of the youngest lava flows in the lower 48, called the Sima Volcanic Field, you can find desert pavements made entirely of lava clinkers. There, beneath the thin lava cover, are thick deposits of fine grained material and then more lava. And a nice thing about lava is it's pretty straightforward to determine how old it is. And the lava on the top of the desert pavement and the lava beneath the fine grained material at the Semavolcanic fields are the same age.
0:32:51 - (Chris Clarke): The most plausible explanation starts with a pile of gravel at the Sema Volcanic Field. That gravel's lava elsewhere. It might be something else, a cobble bar deposited by flash floods or a shallow slope of scree around the base of the mountain. But whatever the origin of the gravel, it's there first. Wind picks up finer sediment from elsewhere and drops it onto the gravel. That finer sediment fills the gaps between the stones.
0:33:17 - (Chris Clarke): In the winter, ice crystals form in the sand and push the stones upward. And in the summer, salt crystals do much the same, as do some scientists suggest the mycelia of soil fungi. Stones get pushed upward a millimeter or so at a time, and that makes more room for silt and sand below. And a windstorm happens by with another load of dust. Lather, rinse, repeat. Eventually you have a thin layer of stones resistant to wind and water, covering a thick reservoir of windblown sediment.
0:33:52 - (Chris Clarke): Desert pavement. However desert pavement forms, it's slow. Ancient geoglyphs created by the ancestors of today's desert Native people were made by simply moving the desert pavement's cobble, sometimes just by raking it away to expose the lighter soil beneath. These artworks are certainly at least several centuries old. This suggests that however desert pavement forms, it's a rather slow process, and thus repair of damage done to desert pavement would necessarily be slow as well.
0:34:23 - (Chris Clarke): Now, the state of Arizona was reminded of the importance of all this back a few years ago, when a monsoon storm traveled over 100 miles or so of desert between Tucson and Phoenix. That desert had once been protected by desert pavement, but bulldozers and grazing cattle and plows and off road vehicles had ground much of that armor into dust. The result was that centuries worth of desert dust ended up in the skies and air filters and lungs of people in Maricopa County.
0:34:53 - (Chris Clarke): Desert pavement doesn't just act as a trap for windblown particulate matter. It's been found to sequester surprising amounts of soil nitrates as well. And that does us all a favor by keeping that fertilizer out of the groundwater supply. Where you have stable soils with significant amounts of nutrients in them, you're likely to find living organisms. And so it's not surprising that desert pavements often hold significant wildflower seed banks in them.
0:35:17 - (Chris Clarke): And a good wet winter will transform the next spring's pavement to a garden. Not every organism living in that soil beneath the top layer of desert pavement is friendly. Desert pavements are a significant reservoir in some parts of the desert for the fungus behind valley fever, which causes severe illness if inhaled. And that's especially true for African American and some Asian American Pacific Islander populations.
0:35:43 - (Chris Clarke): It's an environmental justice issue that desert pavement helps correct. If you leave that desert pavement intact, the fungi will stay safely contained. Bulldoze that pavement and we may find ourselves exposed to once sequestered pathogens for a few centuries. This is the kind of thing I love finding out about the desert. A feature of the landscape that's about as innocuous as you can imagine. A flat expanse of boring gravel turns out to clean our air of asthma inducing dust, helps keep us from catching valley fever, and just as a bonus, gives us flowers every now and then, as long as we keep the bulldozers off of it.
0:36:33 - (Chris Clarke): That wraps up this episode of 90 Miles from Needles, the Desert Protection Podcast. Thank you for listening. This has been an interesting episode to put together. As always, I'd like to thank Joe Jeffrey, our voiceover guy, and Martin Mancia, who created our wonderful podcast artwork, which we hope is not going to turn out to be autobiographical, but Honestly, the way things are going with political world these days, being a journalist, especially a journalist that doesn't have a large corporation looking out for me, doesn't always feel like the safest path. I hope I'm wrong.
0:37:08 - (Chris Clarke): As I mentioned up front, no new donors this week. 90 miles from needles.com donate if you want to change that Our theme song, Moody Western is by Bright side Studio. Other music in this episode is by Canis Latrans. We had a really good meeting of the Board of Directors of the Desert Advocacy Media Network this past week. We hadn't met in a little while, but I was reminded how privileged I am to be working with these folks.
0:37:37 - (Chris Clarke): And maybe you want to too. If you're someone in the desert who loves the desert, if you're experienced in nonprofit law or fundraising or for that matter, keeping track of the books, we could use your advice and your expertise on our board. Get in touch we're especially looking for folks that are not in California because we are pretty California heavy. We have one person from Tucson on our board and all the rest of us are in Southern California, which, don't get me wrong, is a great place to be. Despite what I thought when I was a Northern Californian, I'm happy to admit that I was wrong, but having a little bit of geographic diversity would be a nice thing. So you folks in Marfa that have been looking for someplace to put your energy in the Resistance, or in Las Vegas or Delta, Utah, Gateway to Great Basin national park, get in touch.
0:38:28 - (Chris Clarke): And I need to put this episode to bed because I'm getting up tomorrow to drive from Twentynine Palms to Las Vegas, where I will be picking up my beloved spouse from what used to be called McCarran International Airport. Now Harry Reid, for better or worse, if you ever want to be reminded of why you're together with somebody, you could do what I did recently, which is to accidentally find an archive of the texts that she and I sent each other when we were first getting to know each other and reading through those texts. And I'm not going to share any because, and I want to say I mean this in the nicest possible way.
0:39:06 - (Chris Clarke): It's none of your business. But I can say that it's really nice when the magic is still there. It's definitely changed. It's gotten deeper in some ways more prosaic and work a day, in some ways more magical in other ways. And I wish for you that kind of magic in all of your relationships, whether they're spousal, romantic, friendship, familial, workplace. If we're going to get through this really ugly period, it's going to have to be about the love.
0:39:38 - (Chris Clarke): Next week we'll be talking to author Josh Jackson about the layoffs in the blm, the largest land management agency in the world in terms of acres managed, and how the DOGE layoffs are really getting in the way of them doing their jobs. I am looking forward to bringing you that episode. In the meantime, stay well. Don't read your phone in bed if you can avoid it. And as always, I will see you at the next watering hole.
0:40:05 - (Chris Clarke): Bye now. 90 miles from Needles is a production of the Desert Advocacy Media Network.