Think twice before stepping on that crunchy top layer of soil. It may be a vital ecosystem that you can help protect
Excerpt from this story from Smithsonian Magazine:
Under the dry, piercing heat of the Utah sun, Sasha Reed is growing plots of plants—and bacteria, lichen and fungi, too. But Reed is no farmer, and at first glance, her fields look to be mostly dirt. She’s an ecologist, and what she is growing is cryptobiotic soil.
Also called biocrust, cryptobiotic soil is a community of tiny, dirt-dwelling organisms that form a distinct crust on the top of soil in arid landscapes. These crusts are vital across Earth’s dryland ecosystems, helping to hold loose soil together and prevent erosion. They retain water, provide nooks for other microbes to live in and add nitrogen to the soil.
Cryptobiotic soil often looks like a discolored patch of ground. Upon closer inspection, the stain becomes a mosaic of small, dark lumps, dotted with tiny beds of moss and inconspicuous patches of lichen. But it can also look very similar to regular, crusty soil. Although the crunchy earth might be tempting to trek over, like stomping through a pile of crisp autumn leaves, that’s a major faux pas: Biocrust can take decades to regenerate.
And these days, in addition to getting crushed by boots, biocrusts are threatened by another kind of human footprint: climate change. So researchers are diligently working to learn more about the crusts and how to restore them.
“It’s been a pretty busy but also exciting time, because we’re kind of inventing how to do this,” says Anita Antoninka, a plant and soil ecologist at Northern Arizona University in Flagstaff who studies the crusts.
The drylands where biocrusts reside are vital ecosystems, she says, but they are some of the most degraded around the globe. As biocrusts decline in these areas, soil fertility will drop, and wind erosion will blow away the loose, unprotected dirt. Less water will soak into the ground. Even the carbon cycle could be affected, as there will be fewer tiny life forms absorbing carbon dioxide.
Biocrusts cover around 12 percent of Earth’s land surfaces and inhabit every continent in the world. A major component of these crusts is often photosynthesizing bacteria called cyanobacteria. The cyanobacteria form sticky filaments that act like glue in sandy desert soil, creating a clumpy, crusty surface where fungi and other bacteria take hold.
