The Desert’s Fragile Skin Can’t Take Much More Heat

“When you step on it, you’re restarting a clock that has long since returned to zero,” says Finger-Higgens. PNAS. “And now the system needs to be repaired.”

To keep your plots undamaged, Finger-Higgins prefers to keep quiet about the exact location of your search site. But what should be an immaculate desert bark with white mushrooms looking, he says, is not as healthy as expected. Something is wrong, not only in the Colorado Plateau (which bleeds in four U.S. states: Utah, Colorado, Arizona, and New Mexico), but also elsewhere.

Deserts are, in a way, the forgotten landscapes of climate change. This is even more incredible considering that dry land covers about 40% of the earth’s surface and supports about 2 billion people, with biocrusters covering 12% of our planet’s surface. And yet the Finger-Higgins study suggests that, even without human interference, “warming may partially deny decades of protection from disruption, with biocrust communities reaching a vital turning point.” A “turning point” refers to the time when ecosystems can only withstand much more stress before they fundamentally change.

Rising temperatures and drought mean we may be “surrounding the drain,” Finger-Higgens says. Apparently, nitrogen-fixing lichens remained stable between 1967 and 1996 at 19% of the crust cover, but then dropped from this constant to 5% in 2019. “Our study corroborates much experimental work. “It shows that there are upper limits of heat in the bioflash that we didn’t know completely until recently.”

Bala Chaudhary, a soil ecologist and assistant professor at Dartmouth College who did not participate in the study, agrees. Even if humans are proactive about how their physical presence affects the landscape, “biocrusters are affected by global climate change,” he says.

Of course, it is difficult even for long-term observational studies to eliminate all possible confounders, which is why scientists have also taken experimental steps to simulate biocrusts in a warming world.

For example, between 2005 and 2014, a team used infrared heat lamps to heat a plot of bark on the Colorado Plateau between 2 and 4 degrees Celsius. They also found that the warming caused a decrease in mosses and lichens compared to an unaltered plot of land.

Then there was a 2018 study that looked at data from more than 500 publications and estimated that biocrusters “will decrease by 25 to 40 percent in 65 years, due to climate change caused by human rights and land use intensification. “

“The role of Finger-Higgens offers a little more realism” than these experimental studies, Bowker says. It shows “something that developed over a long period of time in a natural ecosystem.”

So, is it really a big deal to get the desert out of your crunchy skin? If you’ve been in the southwestern United States for a while, you know that it’s very windy and that storm systems can blow through the land. The bark acts as a protective layer, a kind of glue that holds the soil together. Biocrosts are sometimes called ecosystem engineers, says Chaudhary, who compares them to beavers in their ability to alter a landscape.

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