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Biological soil crusts in Canyonlands National Park are affected by a warming climate

textured, black soil crust in the foreground with red and brown rock formations out of focus in the background
B Hartford J Strong
/
flickr
Biocrusts protect desert soil from erosion.

New research reveals that climate change is affecting biocrusts in Canyonlands National Park. Biological soil crusts, or biocrusts, are made up of microorganisms that live on the surface of the soil. In desert ecosystems, biocrusts protect against erosion and help the soil retain water and nutrients. Kristina Young, a USU Extension Assistant Professor in Grand County, said that, to many people, biocrusts are both familiar and mysterious.

“A lot of people just know, there's this fancy dirt that you're not supposed to step on. But people don't know a lot more about it than that usually,” Young said.

Rebecca Finger-Higgens, USGS ecologist at the Southwestern Biological Science Center in Moab, says a biocrust is characterized by a solid layer on the surface of the soil.

“So if you tap the soil, there's there's kind of something holding it together. And those early stages are caused by just free living bacteria in the soil. In systems that have more developed biocrusts, you'll start to get cyanobacteria, then you'll start to get kind of texture and development, and kind of bumpiness on the soil surface. And then ultimately, kind of these more developed biocrusts that haven't been disturbed, … you'll get a little bit more diversity with mosses and lichens,” Finger-Higgens said.

Using data from over 20 years’ worth of scientific observations, Finger-Higgens and her collaborators studied the relationship between environmental conditions and biocrust composition in Canyonlands National Park. Their research demonstrates that, as summertime temperatures have increased, lichen cover and diversity have declined. In particular, the species of lichens that help convert nitrogen in the air to compounds that organisms can use have almost disappeared from the biocrust, from making up 19% in 1996 to only 5% in 2019. While climate change could explain this shift, the consequences for the larger ecosystem are still unknown.

“So we're wondering, if we're seeing one component of the biocrust kind of falter, does that mean that we're going to lose soil stability or lose soil nutrients? …So we don't know if it will sort of trigger a whole community shift, or if other components of the biocrust can kind of take over,” Finger-Higgens said.

Young said protecting biocrusts by staying on trails helps them cope with environmental stress.

“The things that biocrusts and pretty much anything living in the desert can't survive are double disturbances. So, the disturbance of people just kind of physical people on the landscape walking or driving or biking off-trail, and then climate change on top of that – no way, those double disturbances are like a two punch for the organisms in the biocrusts in the desert. And so …stay on the trail might not seem like that big of an action, you know, but really, you're really part of an essential solution to ensuring that the desert, you know, remains healthy and intact," Young said.

Young said the biocrusts in Southeast Utah are iconic, with black pinnacles that mirror the larger rock formations in the area.

"I talk about them as the coral reef of the desert, they're full of colors, and they are full of topography… But you know, biocrust is everywhere, except for in like active washes or active blowing sand dunes. … And so even if an area doesn't look like what you think of maybe as this beautiful coral reef-type biocrust, it's an area that's in recovery, it’s trying to get back there. And so, you know, not stepping on those areas is just as important as not stepping on big, beautiful, pinnacled biocrusts," Young said.

Without biocrusts, wind can turn desert soil into clouds of dust. Dust storms can have serious consequences for human health as well as at the watershed level. Protecting biocrusts means not only preserving the beauty of desert landscapes but protecting the health of those who call the desert home.