Biocrust reduces global dust emissions by 60 percent

In the constant struggle against dust, humans have a deep arsenal of weapons, from microfiber cloths to feather dust and vacuum cleaners. But new research suggests that none of these technologies can be compared to nature’s secret weapon: the biological crust of the soil.

These crustaceans are thin, cohesive layers of soil, clinging to dirt-dwelling organisms, and often cover dry landscapes. Despite being naive, researchers now estimate that these rough soils of the soil prevent about 700 teragrams (30,000 times the mass of the State of Freedom) from falling into the air every year, and dramatically reduce dust emissions worldwide by 60 percent. If measures are not taken to conserve and restore biocides that are threatened by climate change and land use change, the future will be much more dusty, environmentalist Bettina Weber and colleagues reported on May 16 online. Natural Geosciences.

Dry ecosystems, such as savannas, shrubs and deserts, may appear barren, but they are providing this important natural service that is often overlooked, says Weber of the Max Planck Chemical Institute in Mainz, Germany. These findings “really require the conservation of the crust.”

The crustaceans cover about 12 percent of the planet’s land surface and are mostly found in arid regions. They are built by communities of fungi, lichens, cyanobacteria, and other microorganisms that produce adhesive substances that live in the highest millimeters of the soil and collect soil particles. In terrestrial ecosystems, crustaceans play an important role in concentrating nutrients such as carbon and nitrogen and also help to prevent soil erosion (SN: 22/4/12).

And since most of the world’s dust comes from dry land, crustaceans are important for keeping dust attached to the earth. Fallen dust can carry nutrients that benefit plants, but can reduce water and air quality, accelerate melting glaciers, and reduce river flows. For example, in the Colorado River Basin, researchers found that dust not only reduced its ability to reflect sunlight, but also shortened the duration of snow cover by weeks, reducing the flow of melting water into the Colorado River by 5 percent. That’s more water that the city of Las Vegas pulls out in a year, says Matthew Bowker, an ecologist at New Arizona University in Flagstaff who didn’t participate in the new research.

Experiments have already shown that biofuels strengthen the soil against erosion, but Weber and his colleagues were curious about how this effect occurred globally. Therefore, they extracted data from experimental studies that measured the wind speeds required to erode dust from different types of land, and calculated how the sides of the crustal cover would affect dust generation. The average wind speed required to erode dust from soils that are completely protected by crustaceans was 4.8 times higher than the wind speeds for eroding bare ground.

The researchers then included their results, along with data on global crustal cover, into a global climate simulation, which allowed them to calculate how much dust the world was capturing each year.

“No one has ever done that calculation before trying to do it globally,” Bowker says. “Even if their number is off, it shows us that the actual number is probably significant.”

Using projections of future climate conditions and the conditions that biofuels can withstand, Weber and colleagues estimated that by 2070, climate change and land use change could result in biofuel losses of 25 to 40 percent, resulting in global dust emissions. It would increase by 5. to 15 percent.

Conserving and restoring biocrusts will be key to alleviating soil erosion and dust production in the future, Bowker says. Hopefully, these results will help spark more discussion about the effects of land use change on biocritical health, he said. “We need to have those conversations.”

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