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Posts Tagged ‘termite’

Our Friend the Termite

Posted in Uncategorized, tagged , , , , , on August 12, 2024| 2 Comments »

Photo: Jackson School.
A research team treks across a field in South Africa in search of carbon-sequestering termite mounds.

Termites in South Africa build mounds that sequester carbon in the soil, which unbeknownst to them, benefits a planet struggling with climate change. Can humans learn to extend those benefits?

Michele Francis, a researcher in the department of soil science at South Africa’s Stellenbosch University, shares some ideas at the Conversation.

“The landscape along the Buffels River in South Africa’s Namaqualand region is dotted with thousands of sandy mounds that occupy about 20% of the surface area. These heuweltjies, as the locals call them (the word means ‘little hills’ in Afrikaans), are termite mounds, inhabited by an underground network of tunnels and nests of the southern harvester termite, Microhodotermes viator.

“I’m part of a group of earth scientists who, in 2021, set out to study why the groundwater in the area, around 530km from Cape Town, is saline. The groundwater salinity seemed to be specifically related to the location of these heuweltjies. We used radiocarbon dating; dating the mounds, we reasoned, would allow us to see when minerals that were stored in the mounds were flushed to the groundwater.

“The tests revealed far more than we expected: Namaqualand’s heuweltjies, it turns out, are the world’s oldest inhabited termite mounds. … This is more than just an interesting scientific find or historical curiosity. It offers a window into what our planet looked like tens of thousands of years ago, providing a living archive of environmental conditions that shaped our world.

“It is also hugely important today: there is growing evidence that termites have a substantial, but still poorly understood, role in the carbon cycle. By studying these and other termite mounds, scientists can gain a better understanding of how to sequester (store) carbon. This process removes CO₂ from the atmosphere and is vital for mitigating climate change.

“Namaqualand is a global biodiversity hotspot renowned for its spring flowers, but it is a dry area. Surface water is in short supply and the groundwater is saline.

“Although most of Namaqualand receives very little rainfall, there are rare, high intensity rainfall events. When these do occur, the termite burrows on the mound surfaces serve as water flow paths that can harvest rain and channel water into the mound. This causes the salts that built up in the mounds over thousands of years to be flushed into the groundwater system via flow paths created by the tunneling action of the termites, pushing the dissolved minerals ever deeper. This process also pushes down the carbon that slowly built up in the center of the mounds when termites collected plant material and brought it into the mound. …

“The ability of these mounds to sequester carbon is linked to the termites’ unique behavior. The insects transport organic material [from] small woody plants – deep into the soil. This way, fresh stores of carbon are continuously added. …. Deep storage reduces the likelihood of organic carbon being released back into the atmosphere. So the mound acts as a long-term carbon sink.

“Not only do the termites take the organic carbon material deep underground into their nests, but their tunnels also allow dissolved inorganic carbon (known as soil calcite or calcium carbonate) in the mound soil to move into the groundwater along with other soluble minerals. So the termite mounds also offer a mechanism to sequester carbon dioxide through dissolution and leaching of soil carbonate-bicarbonate to groundwater. …

“These findings are further evidence that termites fully deserve their reputation as ecosystem engineers. They modify their soil surroundings to maintain ideal humidity and temperature conditions. …

“Termite mounds can help provide a more comprehensive understanding of global carbon dynamics. In Namaqualand, mounds occupy 27% of the total area but contribute 44 % of the total soil organic carbon stock. …

“Public awareness and policy integration are key, too. Termite mounds are often cleared for agriculture or termites are considered pests. Raising awareness about the ecological importance of termite mounds and integrating these findings into environmental policies can help promote practices that support natural carbon sinks.”

More at the Conversation, here. Listen to the story at The World, here.

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News on Fairy Circles

Posted in Uncategorized, tagged , , , , , , , , , , , , , , , , , , , , , on April 30, 2016| 2 Comments »

Following up on my 2012 post about fairy circles.

Rachel Nuwer writes at the NY Times, “When Stephan Getzin, an ecologist at the Helmholtz Center for Environmental Research in Leipzig, Germany, opened the email, his heart began to flutter. Attached was an aerial image of fairy circles, just as he had seen in countless photos before. But those images were always taken along long strips of arid grassland stretching from southern Angola to northern South Africa. These fairy circles — which looked nearly identical — came from Australia, not Africa. …

“The emailed photo came from Bronwyn Bell, who does environmental restoration work in Perth. She had read about Dr. Getzin’s research in Namibia and made a connection to the odd formations in her home state, Western Australia. …

“Scientists have been interested in fairy circles since the 1970s, but have not been able to agree on what causes the patterns to form. Researchers generally fall into two groups — team termite and team water competition — but there are other hypotheses as well, including one involving noxious gases.

“Dr. Getzin, like others on team water competition, explains the circles through pattern-formation theory, a model for understanding the way nature organizes itself. The theory was first developed not by biologists, but by the mathematician Alan Turing. In the 1990s, ecologists and physicists realized it could be tweaked to explain some vegetation patterns as well. In harsh habitats where plants compete for nutrients and water, the new theory predicts that, as weaker plants die and stronger ones grow larger, vegetation will self-organize into patterns …

“In the case of African fairy circles, the bare patches act as troughs, storing moisture from rare rainfalls for several months, lasting into the dry season. Tall grasses on the edge of the circles tap into the water with their roots and also suck it up with the help of water diffusion through the sandy soil.

“Although similar in appearance, Australian fairy circles turn out to behave differently, Dr. Getzin and his colleagues have found. … Aussie circles feature a very hard surface of dry, nearly impenetrable clay, which can reach up to a scalding 167 degrees during the day. Despite the differences, though, they believe the fairy circles’ function remains the same. When the researchers poured water into the circles in a simple irrigation experiment, it flowed to the edges, reaching the bushy grass …

“The new research ‘moves us closer toward a unifying theory of fairy circle formation,’ said Nichole Barger, an ecosystem ecologist at the University of Colorado, Boulder.

“It could be that more fairy circles are yet to be discovered in arid environments around the world, she said.

“According to Walter Tschinkel, an entomologist at Florida State University, the findings strengthen the claim that the circles are a result of self-organization by plants. He cautioned, though, that to be more certain, scientists would need to control environmental factors — water and termites, for example — to see which produce the predicted outcome.”

More here.

Photo: Norbert Jürgens
Tracks of Oryx antelopes crossing fairy circles in Namibia.

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