Ebene News – UA – Mystery of Africa’s fairy circle finally solved in new study

Posted: 12:02 GMT, February 17, 2021 | Update: 2:10 p.m. GMT, February 17, 2021

African fairy circles in grasslands are formed by a plant that releases toxic sap into the soil when it dies, new study finds

This poisonous sap, which is used by local bushmen to dip the tips of their hunting arrows, comes from the Euphorbia plant species

Researchers say Euphorbia is responsible for bare circular spots in the soil, which are scattered throughout Namibia’s grassy desert and have puzzled the scientific community for decades

Between southern Angola and northern South Africa there are hundreds of thousands of fairy circles, ranging in diameter from 7 to 50 feet (2 to 15 meters)

Two species of Euphorbia – E damarana, E gummifera, and possibly other species like E gregaria – release the hydrophobic sap when they die, inhibiting the growth of other herbaceous plants and creating sterile, bloodless circles. traits, experts reveal

A fairy circle in Namibia, Africa Mysterious circles dotted around the grassy desert have long puzzled scientists

Euphorbia’s death, and therefore the creation of fairy circles, is exacerbated by rising temperatures, they add

Fairy circles are barren patches of land that can be found in the Namib Desert in southern Africa

They can measure from 7 to 50 feet in diameter, are found in the arid grasslands of the region on sandy soils

A ring of vegetation around the edge of the ring is higher than the surrounding meadow

The mystery of how they got there, or why they stay there, has baffled scientists for decades

Theories have included destructive weed gases, termites and even UFOs while local myth holds that a dragon lives beneath the Earth and its fiery breath burns vegetation

The groundbreaking study of fairy circles was conducted by researchers from the University of Pretoria, South Africa and ITMO University in St. Petersburg, Russia

“There are several theories about the cause of fairy circles,” Professor Marion Meyer from the Department of Plant and Soil Sciences at the University of Pretoria told MailOnline

Euphorbia plants are locally known as the milk bush for their white, gummy, poisonous sap that oozes from its branches

Euphorbias are succulents – meaning they have thick, fleshy leaves, usually to retain water in arid climates or soils – and can cause permanent blindness in humans if its sap comes into contact with the eyes

“I have worked with four postgraduate students for several years, approaching it from the angle of soil chemistry, biological toxicity and geographic angles,” said Professor Meyer

‘We are really convinced that Euphorbia’s milk bushes caused, and still cause them today’

Fairy circles are mostly confined to a narrow strip, about 30 to 60 miles (50 to 100 km) inland from the Atlantic Ocean, which extends southwest of Angola, through Namibia to north-western South Africa

It was reported in 2017 that fairy circles are partly caused by “ underground ecosystem engineers ”, such as termites, ants or rodents

Another possible explanation, known as the “self-organizing theory”, was that competition for water causes plants to position themselves in such a way that the roots can best access the water. rainfall runoff

“ Despite a plethora of research on termite activity, soil chemistry, soil hydraulics, and other inherent properties of the fairy circle, there are still a number of different theories attempting to explain their origin and maintenance, ” says the team

Aerial view of fairy circles, located in the Namib Desert, in Namib-Naukluft National Park of Namibia

Due to a lack of scientific evidence for previous theories, Professor Meyer began a multidisciplinary study in 2015 on the effect of Euphorbia species on the soil and water chemistry of the Fairy Circle

Euphorbia inhibits germination and also has antimicrobial properties against bacteria in the rhizosphere – the part of the soil next to the roots

The plant colonized the sandy plains when climatic conditions were more favorable in the past, suggest the researchers

Since sandy soils have low water holding capacity, Euphorbia would have been under pressure for water and nutrient availability

Over time, with rising temperatures, lack of water and competition for nutrients resulted in increased competition between these plants and many are believed to have died

Namibia’s temperature increase over the past two to three decades is about three times the average global temperature increase reported for the 20th century

The decomposition of dead Euphorbia plants and the resulting sticky latex that oozes and disperses makes the surrounding sandy soil water repellent (or “ hydrophobic ”)

Various other compounds are also said to have entered the soil from decomposing euphorbias, which are said to have had toxic and antimicrobial properties

Fairy circles tend to be found in hot spots of the Namib Desert on the eastern coast of Namibia, as shown on the map above

Most of these compounds would probably have broken down in a relatively short time, but milky latex can adhere to sand, become hard and persist in soil for a long time

These soil changes cause many fairy circles to form, causing a transition from a site with only plants, to a mixed site with plants and fairy circles, and then a site with only fairy circles.

Seeds have been observed to germinate inside fairy circles and seedlings emerge after good rains, but only survive for short periods after rains

Euphorbia seedlings in fairy circles also die because water from the soil seeps past their roots

Euphorbia gummifera at Garub near Aus (d) and in the same area in a Google Earth image (e)

The ‘fairy circles’ have long been one of nature’s greatest mysteries, sparking wild theories that they were created by aliens or legendary gods In the photo, E damarana co- occurrence with fairy circles in Brandberg

However, fairy circles are not permanent, the team suggests – over decades, if not centuries, with occasional rains, the toxicity in the circles will slowly erode.

This means that the seedlings will survive longer in the old fairy circles until they are finally fully established and reach maturity, and the fairy circle will no longer be visible as it is covered by new growth.

Soil analyzes by gas chromatography / mass spectrometry (GC / MS) were carried out at ITMO University, with the assistance of Professor Denis Baranenko

They revealed that the soil of the two fairy circles and of the decaying sub-E damarana plants, are very similar in phytochemistry

Several previously identified compounds with antimicrobial and toxic activity have also been identified in E gummifera, another species of Euphorbia

Finally, by integrating precipitation, elevation and land cover into a GIS spatial modeling model, the researchers predicted where the fairy circles should appear

The model largely agreed with the distribution of three Euphorbia species and resulted in the new discovery of fairy circles in the far south-eastern part of Namibia and even in the Kalahari Desert of South Africa. South

Site suitability prediction map for fairy circles distribution in Namibia (areas where previously reported fairy circles are found southwest of the Orange River are not included)

A circle of fairies taken at sunset in Namib Naukluft Park It is only from the air that it is possible to see their scale and extent

Historical aerial imagery has also shown that in a population of 406 E gummifera in southern Namibia, 134 have been replaced by fairy circles over a 50-year period

This study has shown that Euphorbia can explain the formation of fairy circles at specific sites across Namibia, where these succulents coexist with fairy circles

Further research is currently underway in areas that have many fairy circles but where large populations of euphorbia are not currently present, such as in the Namib Rand and Marienfluss Nature Reserve

“We plan to analyze ancient pollen inside samples of Hyrax midden hundreds to thousands of years old to determine if Euphorbia milk bushes were in these areas and may have been -be extinct because of climate change, “Professor Meyer told MailOnline

Scientists claimed in 2013 that the sand termite species Psammotermes allocerus was the most likely suspect for the creation of fairy circles

Norbert Jürgens of the University of Hamburg said the insect was the only species consistently present across the 1,200 miles of desert that included the circles

His theory focuses on termites that eat plant roots before they can sprout through desert soil, creating a water trap – in the same way beavers create dams

Due to the lack of foliage, rainwater is not lost through transpiration – the evaporation of water from plants – and instead remains below the surface

This allows sand termites to survive and stay active during the dry season and also helps grasses at the edge of the circle to thrive by attracting other life forms

Others have suggested that the activity of termites building nests below the ground causes the release of poisonous gas which causes the death of plants above

Some have suggested that a pathogenic fungus could be responsible or the plots are the old sites where highly toxic spurge bushes grew

The most recent theories suggest that the circles follow rainfall patterns and may be caused by competition between plants, with stronger, more vibrant grass circles sucking nutrients and moisture from poor soil. in the center

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Ebene News – UA – The mystery of the circle of the fairies in Africa is finally solved in a new study

Source: https://www.dailymail.co.uk/sciencetech/article-9269439/Africas-fairy-circle-mystery-finally-solved-new-study.html