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© Penn State. Creative Commons – psu.edu | Graduate student Ryan Trexler collects cores of biocrust from the field before bringing them back to the lab to study.

Microbe-stuffed soil crusts menaced by climate change

Novel approach to measuring microbe activity in wetted soil leads to better understanding of vulnerability, researchers report.

Using a novel method to detect microbial activity in biological soil crusts, or biocrusts, after they are wetted, a Penn State-led research team in a new study uncovered clues that will lead to a better understanding of the role microbes play in forming a living skin over many semi-arid ecosystems around the world. The tiny organisms — and the microbiomes they create — are threatened by climate change.  

The researchers published their findings in Frontiers of Microbiology.

“Biocrusts currently cover approximately 12% of Earth’s terrestrial surface, and we expect them to decrease by about 25% to 40% within 65 years due to climate change and land-use intensification,” said team leader Estelle Couradeau, Penn State assistant professor of soils and environmental microbiology. “We hope this work can pave the way to understanding the microbial functions supporting biocrust resilience to the rapidly changing climate patterns and more frequent droughts.”

Biological soil crusts are assemblages of organisms that form a perennial, well-organized surface layer in soils. They are widespread, occurring on all of the continents wherever a shortage of water limits the growth of common plants, allowing light to reach bare soil. But there is still sufficient water to support the growth of microorganisms that perform valuable ecosystem services such as taking carbon and nitrogen from the air and fixing them in the soil, recycling nutrients and holding soil particles together, which helps prevent dust.

That soil-stabilizing function — which reduces erosion by providing the means for soil to clump and not break down into dust — is extremely important, according to Couradeau. Her research group, now in Penn State’s College of Agricultural Sciences, has been intensively studying biocrusts for a decade.

“Most dust is generated in drylands, and studies suggest that the presence of biocrusts in drylands greatly reduce the amount of dust that would otherwise make its way into the atmosphere,” she said. “We think losing biocrusts would cause a 5% to 15% increase in global dust emission and deposition — which would affect the climate, environment and human health.”

In the semi-arid regions where biocrusts exist, the organisms — tiny mosses, lichens, green algae, cyanobacteria, other bacteria and fungi — may experience just a few rain or snow events a year, explained Ryan Trexler, a doctoral degree candidate in the Intercollege Graduate Degree Program in ecology and in biogeochemistry, who spearheaded the research.


Pennsylvania State University 2023

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