On a cloudless September morning in Buffelsrivier, a desolate nook of Namaqualand some 530km (329 miles) north of Cape City, Stellenbosch College soil scientists Cathy Clarke and Michele Francis watch as a large Volvo excavator tears into the dry ochre earth. Over the following 5 hours the excavator works exhausting to dig a trench, 60m (197 toes) lengthy and 3m (10 toes) deep, by means of the guts of a large, low-slung mound identified regionally as a heuweltjie or “little hill”. It’s all a part of a college undertaking to grasp why the groundwater within the space is so salty.
As soon as the digger has returned to the close by city of Springbok, inhabitants 12,790, Clarke, Francis, and a bevvy of grad college students start to discover the ditch. They begin at its extremities, what Francis describes because the “boring bits”, feeling the soil and searching for indicators of life. As they transfer inwards, they begin to discover small conglomerations of bewildered southern harvester termites (Microhodotermes viator) furiously making an attempt to restore the injury completed to their residence.
On the centre of the ditch, two metres (6.6 toes) beneath floor degree, they encounter “this enormous nest that appears like a large alien”, Francis tells Al Jazeera. Clarke nods in settlement: “The second I noticed it I knew we had been witnessing one thing particular. It was simply so clearly historical … And alive.”
As soon as they’d taken a while to easily marvel on the work achieved by these 1cm (0.4 inch)-long creatures, they moved on to the enterprise at hand: taking soil samples. “I delegated the duty to a younger male scholar with a pickaxe,” laughs Clarke. “However he couldn’t get the metal blade to penetrate the edges of the ditch.” The bottom was so exhausting, based on John Midgley – an entomologist on the KwaZulu-Natal Museum who was not concerned within the undertaking – as a result of it was a part of an “historical mound” created by termites over hundreds of years. Ultimately, after plenty of huffing and puffing, the grad scholar was in a position to get hold of a pattern the dimensions of a soccer ball, which was despatched for testing.
This type of problem is all in a day’s work for soil scientists, says Clarke, who describes her self-discipline as “a enjoyable mixture of every part from bucket science to excessive precision X-ray strategies”.
Francis tells me that once they obtained again to their lodge in Springbok on the finish of the day, the cleaner reported them to the supervisor: “She thought we had been zama zamas [South African slang for illegal miners] as a result of our rooms had been coated in orange dust,” she says, including, “I assume she [the cleaner] had some extent.”
How previous is previous?
The soil scientists knew instinctively that they’d dug up a really previous termite nest. However neither of them was ready for fairly how previous it could be. They submitted samples for radiocarbon courting from the nests and soils from areas throughout the enormous mound. These checks analysed the soil natural carbon (decomposed natural matter dragged into the nests by termites) and the soil mineral calcite (inorganic carbon within the type of calcium carbonate) to provide a whole image of the mound’s age.
The checks confirmed that the natural matter dragged into the nest by the termites had been there for not less than 19,000 years. The mineral calcite within the nests, additionally a results of termite exercise, was even older: It had been round for 34,000 years, since earlier than the final Ice Age.
Francis is fast to level out that “this doesn’t imply the termites had been dwelling in ice”. As she explains, in arid elements of the world, the Ice Ages had been really a time of a lot: “The Namaqualand acquired considerable rainfall and was a magnet for animals of all sorts.”
Whereas the entomologist Midgley has little question that termites have been energetic within the space for not less than 30,000 years (fossilised nests had been first discovered within the space within the Thirties), he says there isn’t any manner of proving that the nest has been frequently inhabited for all of that point. “There’s a excessive density of nests within the space. Recolonization appears inevitable, if not essentially intentional,” explains Midgley.
Both manner, analysis by Clarke and Francis shines a light-weight on the function these misunderstood bugs play as ecosystem engineers. Not less than 165 termite species, from 54 genera, are present in southern Africa. Though there are massive variations between genera they’re all characterised by a excessive diploma of social organisation, with every species containing a number of distinct “castes”. Relying on their caste – reproductive (king and queen), soldier or employee – termites of the identical species can look and behave fully in another way.
Southern harvester termites primarily feed on sticks and twigs, which they carry down into their nests: in Afrikaans, they’re referred to as stokkiesdraers (stick carriers) or houtkappers (woodchoppers). Past these nicknames, most individuals know little or no about them – in reality, they’re usually confused with ants. The one time termites are usually talked about is when farmers moan in regards to the destruction they wreak on pastures. Utilizing pesticides to kill termites stays a standard apply.
Termites could have a nasty rap, however Clarke’s and Francis’ analysis highlights one of many long-term advantages of their stick-eating. Over millennia their redistribution of natural matter drastically alters the composition of the soil, successfully creating two totally different habitats in the identical biome. Some plant species love the mineral-rich soil of the heuweltjies, whereas different vegetation have tailored to rising in soil that’s not inhabited by termites.
“The termites are one of many causes for the Namaqualand’s unimaginable biodiversity,” says Clarke. The biome, identified formally because the Succulent Karoo, is taken into account “the world’s most biodiverse desert region“.
However this isn’t the one manner they profit the planet.
An unintended discovery
The heuweltjies shaped by southern harvester termites are fairly in contrast to the dramatic pinnacles constructed by different species in Africa, Australia and South America. However this doesn’t make them any much less fascinating. Measuring as much as 40 metres (132 toes) in diameter, these raised mounds containing intricate networks of termite tunnels and nests cowl as much as 27 p.c of the floor space of Namaqualand. Scientists are divided over whether or not the termites really assemble the heuweltjies – however even sceptics admit that the termites play a essential function of their formation.
The southern harvester termite has a broad distribution vary, however heuweltjies – that are the results of a buildup of advantageous soil materials, carbon and salts over centuries – solely kind in semi-desert areas. The southern harvester termite can be frequent in and round Stellenbosch (the picturesque Winelands college city, about 50km east of Cape City, the place Clarke relies), however the heavy winter rains and dense vegetation stop mound formation. Right here the presence of the termites is highlighted by massive bush clumps within the scrubby fynbos (native vegetation) and in nutrient-rich patches in vineyards and fruit orchards.
Buffelsrivier, which receives round 4 instances much less rain than Stellenbosch, is a distinct story. Large, dense heuweltjies dot the panorama so far as the attention can see. In springtime, they’re particularly straightforward to identify, because the heuweltjies are ringed by halos of flowers.
Clarke and Francis began investigating the Buffelsrivier heuweltjies in a bid to grasp why the groundwater within the neighborhood was so salty – termites had been solely a sideshow. “The goal was thus far the groundwater,” explains Francis. “Was it very previous? Or was it being recharged each time it rained?”
Whereas courting the water, they needed to date the sediments round it. This course of didn’t simply result in the unintended discovery of some very previous termite nests. It additionally confirmed that the salts and different minerals within the groundwater had been the direct results of termite exercise. When it rains, Francis explains, “the salts built up in the mounds over hundreds of years are flushed into the groundwater system by way of movement paths created by the tunnelling motion of the termites, pushing the dissolved minerals ever deeper.”
An missed carbon sink
Whereas this offered a definitive rationalization for the area’s hypersaline groundwater, it additionally obtained the scientists fascinated by the function termites would possibly play in combating local weather change – one thing which had by no means been thought of for this species.
By dragging sticks and twigs underground, the termites add contemporary shops of natural carbon to the bottom at depths higher than one metre (three toes). This deep storage of natural carbon, explains Clarke, “reduces the probability of the carbon being launched again into the environment and signifies that the mound acts as a long-term carbon sink”. The continuous harvesting of plant matter additionally will increase the fertility standing of those mounds. Therefore the halos of spring flowers.
However the termites’ powers of sequestration don’t finish there. The organic breakdown of termite excrement (often called frass) triggers a cascade of organic reactions, which ends up in the formation of calcium carbonate – the fabric limestone is product of. This calcium carbonate is a really secure type of carbon that’s locked within the soil for hundreds of years. A few of this carbon leaches into groundwater the place it could stay for hundreds of years.
“That is the form of long-term carbon storage [14.6 metric tonnes] methodology that carbon storage firms try to copy,” says Clarke. “However the termites have been doing it for hundreds of years.
“It’s time we stopped viewing termites as pests and began to see the vital function they will play in combating world heating.”
Midgley, the entomologist, agrees, “Termites are fascinating creatures that promote biodiversity in diverse and sudden methods. For instance, we discovered a species of hoverfly that relies on termite frass as a larval habitat … with out termites, it could go extinct. The extra we discover, the extra fascinating facets of termite life will emerge.”
Clarke and Francis consider that “termite exercise needs to be included into carbon fashions”. These fashions at present focus totally on forests and oceans, so “together with termite mounds might assist present a extra complete understanding of world carbon dynamics”.
Solely scratching the floor
Till Clarke’s and Francis’ discovery, the oldest natural matter present in a termite colony got here from a 4000-year-old rooster in Brazil. That mentioned, only a few research have used heavy equipment to penetrate the exhausting crust shaped by the bugs, so there’s a great probability there could possibly be even older colonies on the market – both in Namaqualand or elsewhere.
Regardless of being a soil scientist and never an entomologist, Francis admits to having fallen for the honey-hued bugs and their complicated societies. “I do know we’re not imagined to ascribe human qualities to bugs,” she says. “However I can’t assist myself. If I had limitless time and funding, I might like to excavate termite mounds all all over the world.”
For now, nevertheless, she’ll must content material herself with a follow-up undertaking that takes a extra in-depth have a look at the mechanisms of carbon sequestration within the Namaqualand heuweltjies. Stellenbosch College initiated the undertaking, however due to a multinational grant funded by the Nationwide Science Basis (US) and the Nationwide Analysis Basis (South Africa), the undertaking now boasts a staff of microbiologists, ecologists and geochemists from the US and South African scientists.
Finally, these pint-sized ecosystem engineers are getting the eye they deserve.
