Fairy circle (arid grass formation)

Fairy circles are circular areas of land devoid of vegetation, with a diameter ranging from 2 to 12 meters (7 to 39 feet), and are frequently surrounded by a ring of grass that has been coaxed to grow.

They may be found in the dry grasslands of Western Australia’s Pilbara region and the Namib desert in western sections of Southern Africa. Numerous theories on their formation have been proposed by studies, but none of them have been able to provide solid evidence. Various termite species’ activities and the results of naturally occurring vegetation patterns resulting from grass-grass competition are examples of theories.

The Aboriginal Australian people who live in the Pilbara region are referred to as mingkirri (a Warlpiri language) or linyji (a Manyjilyjarra language).

Location

Only the dry grasslands of the Namib desert in western sections of Southern Africa were known to experience the occurrence until 2014; Namibia was found to be severely affected. That year, ecologists discovered comparable vegetation rings in a section of Western Australia’s Pilbara, which is not in Africa.

The circles are located in a belt in Africa that is around 160 km (100 mi) inland and stretches from Angola southward for about 2,400 km (1,500 mi) to the South African province of the Northwestern Cape.

The majority of the area is inaccessible and hostile, with several parts being more than 100 kilometers away from the closest settlement. The circles have been acknowledged and discussed informally for a long time; they were first brought up in technical literature in the 1920s and then sporadically after that, with research on them intensifying in the latter quarter of the 20th century.

In the Pilbara area of Western Australia, 15 km (9.3 mi) outside of the town of Newman, fairy circles were first seen in 2014. In a research published in 2016, Australian environmental engineer Bronwyn Bell and Stephan Getzin of the Helmholtz Centre for Environmental Research offered fresh insight into a potential explanation for the genesis of fairy circles.

Examples are located in Namibia at 24.95°S 15.93°E and in Western Australia at 23.45°S 119.85°E.

Description

Generally speaking, fairy circles are found in virtually monospecific grassy plants in extremely dry environments. Species of the genus Stipagrostis are frequently associated with grasses. Studies suggest that these rings move through a life cycle of about 30 to 60 years.

When they reach a maximal diameter of around 12 meters (39 feet), they become evident at a diameter of roughly 2 meters (6 feet 7 inches). After that, they mature and “die” when they are invaded, primarily by grasses.

Fairy circles are referred to as “linyji” in the Manyjilyjarra language and “mingkirri” in the Warlpiri language by the Martu and Warlpiri peoples of Western Australia. However, termite linyji are actually ordinary vegetation gaps rather than actual fairy rings, according to science.

Theories of formation

Similar to heuweltjies in South Africa and Mima mounds in the United States, fairy circles have long eluded explanation, and research into them has been difficult. Namibian fairy circles were made of sand, not clay, hence their construction may differ from that of Australian fairy circles.

Gretel van Rooyen, a botanist at the University of Pretoria, denied suggestions in 2004 about termite activity, radioactive soil, and plant poisons. In 2008, Angelique Joubert hypothesized that the arid interiors of the circles might be caused by leftover plant poisons in the soil following the death of Euphorbia damarana plants.

Eugene Moll proposed in 2012 that the termite species Psammotermes allocerus and Baucaliotermes hainsei were the originators of these circles. Termite castings have been discovered in every ring, and radar studies indicate that the fairy circles are supported by a wet layer of soil.

Norbert Juergens endorsed this hypothesis in 2013. Juergens discovered proof that Psammotermes allocerus, the sand termite, creates a small environment that benefits from and encourages the formation of the fairy circle.

The sand termite was discovered in 80-100% of the circles, in 100% of freshly created circles, and was the only insect to exist across the extent of the phenomena. The fairy circle is made by sand termites eating plants and excavating a ring in the ground. The barren circle keeps the soil wet even in the driest weather by enabling water to seep through the sandy soil and collect below the surface.

The collected soil water encourages the development of grass surrounding the circle, while termites eat the grasses, gradually enlarging the circle’s diameter. Psammotermes allocerus’s actions equate to the establishment of a local ecosystem in a way that is comparable to that of ordinary beavers.

Juergens, according to Florida State University biologist Walter R. Tschinkel, “has made the common scientific error of confusing correlation (even very strong correlation) with causation.”

Tschinkel also conducted a study on fairy circles. Tschinkel had previously looked for harvester termites but had not been successful. In response, Juergens said that sand termites are not like harvester termites in that they dwell much below the circle, don’t build nests or mounds above ground, and don’t leave any trace in the sand. In these aspects, the sand termite’s activity is quite subtle.

There are still unanswered concerns regarding how the dirt in the circle’s center hinders plant development and how different species interact with the surrounding ecology within the fairy circle. Remarking on the “heuweltjies” being anomalously rich in plant nutrients, the conventional knowledge from approximately a century ago raised the question of how many effectively distinct sorts or conditions of circles or heuweltjies there may be.

Subsequently, in 2013, Michael Cramer and Nichole Barger proposed that the circles resulted from naturally occurring vegetation patterns caused by grass-grass competition. They looked at the variables that lead to fairy circles and discovered a negative correlation between soil nutrition and precipitation.

This discovery supports the theory that the circles are caused by competition for resources. Bare patches can occur in grassy environments with a variety of grasses due to underground competition between various grass species. According to the aforementioned argument, termites may be responsible for the patches’ maintenance since they provide as a source of nutrients for the higher grasses around the edges.

They can forecast the existence or absence of fairy rings in an area with a high degree of accuracy using temperature, biomass, and rainfall seasonality. Walter Tschinkel claims that this hypothesis explains every aspect of fairy rings, including the existence of species of tall grass. In other recent research, interlocking combinations of patterning effects caused by plants and animals have been explored as a possible unifying theoretical explanation for the phenomena known as the fairy circle.

According to a 2015 idea on the Australian fairy circles, the unique vegetation patterns result from competition for limited water resources at the population level, wherein plants “organize” themselves to maximize their availability.

Water is collected by the round, desolate areas and then runs out to the ring’s boundaries. Increased biomass and roots from more water availability cause the soil to become looser. Because the soil is less compact, more water may permeate it and nourish the plants, which sustains the plants near the circle’s perimeter through a feedback loop.

This is supported by field observations conducted in Namibia in 2015 and 2016 by Sujith Ravi, Lixin Wang, and colleagues utilizing measures of soil moisture, soil particle size, and soil water penetration.

The Turing mechanism and hydrological feedback were suggested as the source of the Australian patterns in 2021.

Excavating hundreds of grasses within and around the fairy rings, the research released in 2022 examined the notion of plant self-organization for Namibia as well as the termite theory. The study found that although termites may have caused root herbivory, the grasses within fairy rings died from plant-water stress rather than from termite herbivory since their roots were originally unharmed and as long as or longer than those of the important grasses outside. “The new study showed “conclusively” that termites were not a factor,” according to many fairy circle researchers.

In February 2023, weak leaks of hydrogen through faults, cracks, and dispersed across rocks, were detected as a likely source of the depressions. According to one study, “hydrogen-loving microbes” may eat up every other nutrient in the soil.

Drepanotermes (Australian harvester termites) occupy pavement nests, according to Australian cross-cultural research released in April 2023 that involved the local Martu peoples and used their traditional knowledge of the phenomena.

According to the findings, termites may have lived in and were still building the rings throughout the Pleistocene, which is over 12,000 years ago. Indigenous Australians have been on the land for up to 65,000 years, and their oral traditions have preserved a wealth of information. Nevertheless, the exact process causing the Australian fairy circles was not taken into consideration in this investigation.

Abiotic weathering of the soil surface produces clay crusts and inhibits grass growth within the circles, as evidenced by extensive studies on the particular Australian fairy circles carried out between 2014 and 2019.

Birth and death

The “birth and death” of fairy circles—that is, their emergence and disappearance throughout time—is an intriguing phenomena. While some fairy rings may have endured for decades, others may have vanished in a matter of 10 years or less.

Long-term cycles of births and deaths can cause regime alterations, like the ecosystem’s desertification. This suggests that these occurrences could be a sign of a more extensive alteration of this terrain, meaning that seeing the emergence of fairy rings is a sign of a process of slow desertification. Researchers have attempted to determine if intervention—such as altering the system’s water content, for example—can cause such a birth or death.

Consequently, this may aid in ascertaining the actual reason behind fairy circles.

Myths

These arid areas are attributed to the gods, spirits, and/or natural divinities in the oral tales of the Himba people of the Kunene Region in northern Namibia. They have long been associated with psychic and magical abilities by the bushmen of the area. Regarding particular beliefs, the Himba people mention that the fairy rings were either made by their original ancestor Mukuru, or that they were the gods’ footsteps.

Another myth that has been spread, especially by certain tour operators in Namibia, is that the dragon who made the circles in the dirt killed the plants with its poisoned breath.

Use

The Himba people cultivate their crops using fairy rings. Fairy circles offer grazing because they encourage the growth of grasses in otherwise arid areas. Occasionally, they build makeshift wooden fences around the circles to confine young cattle and provide them with nocturnal protection from predators.

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