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PRI's Environmental News Magazine

Using Bacteria to Heal the Desert Erosion

Air Date: Week of August 15, 2014

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Desert (Photo: Project 1080; Flickr Creative Commons)

Erosion is a huge problem in the dry American West. But there's hope; soil scientist Matthew Bowker of Northern Arizona University tells host Steve Curwood he's using bacteria to help bring a living crust back to the surface of the desert.

Transcript

CURWOOD: It's Living on Earth. I'm Steve Curwood. Soil is the delicate skin of the Earth that holds everything from complex microbial systems to vast amounts of carbon that would otherwise add to global warming. Human activities have led to a lot of soil loss over the years, so some people are busy working on new approaches to help reverse that trend. One of them is Matthew Bowker, who teaches at the Northern Arizona University School of Forestry and studies how damaged soil crusts might be restored. He sees much of the soil loss out in the desert west as the direct result of recent weather events and land use changes.

BOWKER: For the last 15 years or so, we've seen out in the west, an awful lot more dry years than wet years, also pretty warm temperatures, and that in conjunction with land use impacts that people have out on the landscape, we’re seeing increasing emissions of dust in the air. So the dry west is becoming a dustier place.

CURWOOD: Now how does this loss of soil affect the environment in the long run?

BOWKER: Not only are you losing soil that took a very long time to develop and accumulate, some of the dust from the deserts in the southwest finds its way up to the snowpack in the Rockies and the San Juan Mountains. It’s darker than snow, so it speeds up the timing of snowmelt, in such a way that some of the snow is lost straight back to the atmosphere, and it increases the snow-free period so that plants are up and running earlier and consuming water up into the mountains earlier because of this dust from the desert. And when that happens, there’s less snowmelt runoff going into the rivers, and this affect is sizable. This is decreasing the snowmelt flow to the Colorado River by about five percent.

CURWOOD: So what are you doing to address this? Talk to us about your research.

BOWKER: Well, I am seeking to rebuild the living skin of the Earth. I study a not-very-well-known desert community of organisms called biological soil crusts, and what these are—it’s a sort of an amalgam of cyanobacteria which you may be familiar with as blue-green algae, and also mosses and lichens—and they grow just sort of in a thin veneer on the desert soil surface. They’re common in deserts throughout the world. But the thing with these guys is they are very easily lost due to physical disturbances, things like livestock hooves or vehicle tracks or human footprints, and they don’t come back very fast. So, a lot of my research is focused on finding ways and building a technology to rebuild these soil crusts.

CURWOOD: How do you do that?

BOWKER: Well, some of these organisms you can grow in the laboratory. The idea is that once you learn how to cultivate these guys really well, and cultivate the right ones, you then need another technology to sort of deploy them back out into the environment in such a way that they become established. The technology does not really exist yet to do it on a really big scale, with the exception of some fascinating stuff they’ve done in China where they’ve actually used straw to stabilize sand dunes, and once they create the stability, they have been able to just naturally grow back both plants and these biological soil crusts. It still takes a while. It takes a couple of decades to get a strong biological crust going, but it’s an awful lot faster than recovery on a mobile dune which you know, you could sit around waiting for hundreds of years.

CURWOOD: So let’s fast-forward and say you, in fact, find a way to reproduce and then distribute this stuff on the soil. Where do you think this approach would be most useful here in the U.S.?

BOWKER: All the livestock in the west are creating issues with the trampling due to their hoof action and the impacts they have on these crusts. So I think what you could do is in a place that has been impacted by too much grazing, you could use this technology to sort of heal that area, and I think the other area would be in finding dust emission hot spots. Dust is kind of a hot spot driven thing. There’s a little bit of dust coming from the entire west, but there’s an awful lot of dust coming from a handful of places. So, a technology like this could maybe be strategically deployed in places that we identify that are emitting an awful lot of dust.

CURWOOD: Where are some of those dust hot spots right now?

BOWKER: There’s one south of Phoenix. There’s a big area of some used, some abandoned cropland. Just east of Flagstaff there’s a big area that blows dust straight to the San Juan Mountains. It’s kind of a triple whammy of naturally erodable soils, some land use impacts, and our drought conditions. That’s why it’s blowing a lot lately.

CURWOOD: So that dust hotspot near Phoenix—we see that on television from time to time, when a cloud just makes the city disappear.

BOWKER: Yes, in fact, the Arabic word for “haboob” is a word for dust storms that is now part of the lexicon in Phoenix. People know that word now because they’re getting used to these storms that slowly roll in that are thousands of feet high.

CURWOOD: So overall, what do you think is the potential to use these organisms to heal the soil? To what extent could you solve erosion problems on a large scale?

BOWKER: That’s yet to be seen, but I think the potential is great. You know, if we solve all these technical problems and put in the research and development, we could really have the solution to these issues. You know, before, we’d usually try to attack more problems like this by trying to get more vegetation to grow, and adding a bunch of seed to the environment, but that ends up being a very expensive practice that really does not work well at all. Basically we need something that works better, and will continue to work better as our climate keeps getting warmer and possibly dryer.

CURWOOD: Matthew Bowker is an ecologist at Northern Arizona University. Thank you so much for taking the time today, Matt.

BOWKER: Thank you very much. It was a pleasure.

 

Links

Check out Mathew Bowker’s article describing his work

Mathew Bowker’s page at Northern Arizona

 

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