How Forming ‘Fairy Circles’ May Help Salt Marshes Adapt to Climate Change

This confirms that fairy rings tend to be nutrient depletion events.  We knew this was true for mushrooms, but now we see it duplicated in the stressed environment of the salt marsh.

Plenty of environments are stressed and the presence of depletion signals which is the paucity of specific plants can be used to plan remediation.

All good but na na to do with climate.

How Forming ‘Fairy Circles’ May Help Salt Marshes Adapt to Climate Change

The transient rings’ secret to survival may be their ability to shape-shift based on nutrient availability

Salt marsh fairy circles may bounce back from environmental stresses because of their ability to merge and form a lush ecosystem after oxygen and nutrient depletion. (Quan-Xing Liu)

By Elizabeth Gamillo

FEBRUARY 25, 2021 8:05AM

https://www.smithsonianmag.com/smart-news/transient-fairy-circles-may-give-clues-how-adaptable-salt-marsh-ecosystems-are-climate-change-180977095/

Mysterious circular patterns, often called "fairy circles" appear all around the world in different climates—from the arid regions of Australia and Namibia to the salt marshes along China's coastline. The peculiar patterns have long captivated humans, sparking myths of fairies or deities creating them. But new research published in Science Advances shows not all fairy circles behave and form the same way.

Fairy rings that form in salt marshes seem to change shape based on nutrient availability and could indicate the ecosystem's resilience to climate change, reports Bethan Ackerley for New Scientist.

Previous research has focused on fairy circles that retain a similar shape and pattern over time. Their spotty formation was attributed to Alan Turing's mathematical theory known as a Turing Pattern. These Turing rings form by chemically repelling each other, leading to distinct identical circular patterns, reports Tara Yarlagadda for Inverse. But transient fairy circles that change shape over time have not been widely studied. Unlike stable fairy circles, transient ones vary in shape, sometimes appearing as a single spot, rings, concentric circles, or eventually, merging together as one, reports New Scientist.

To find out why transient circles form in salt marshes and exhibit this behavior, Li-Xia Zhao and her team from East China Normal University used computer modeling to recreate ring patterns seen in the marshes. They then simulated nutrient depletion in the center of the rings and rising sulfide levels caused by bacteria decomposing plant matter, reports Meagan Cantwell for Science. At various points in and around the fairy circles, the researchers collected soil samples and studied two plant species, a sedge (Scirpus mariqueter) and salt marsh cordgrass (Spartina alterniflora), reports New Scientist.

Zhao and her team found that samples taken from the center of the ring had higher concentrations of sulfides and less access to nitrogen—and both conditions limit plant growth. The fairy circles' varying shapes correlated with where nutrients and oxygen were depleted, reports New Scientist. When the researchers added fertilizer to the circles' outer edge, they found little to no difference of growth, but when added to the center of the ring, they found growth where no plants previously were, Science reports.

"Through a controlled experiment with the addition of nutrients, we further found that the nutrient depletion mechanism has a dominant contribution to the self-organizing patterns of such 'fairy circles,'" study co-author Quan-Xing Liu, an environmental scientist at East China Normal University, tells Inverse.