Figs can benefit to the climate by transforming carbon dioxide into stone

Some figs can convert surprisingly significant quantities of stone carbon dioxide, ensuring that carbon remains in the soil long after the death of the tree. This means that figs planted for forestry or their fruits could offer additional climatic advantages thanks to this carbon sequestration process.

All trees take the CO₂ Air, and most of this carbon is generally found as structural molecules used to build the plant, such as cellulose. Some trees, however, convert co₂ In a crystalline compound called calcium oxalate, which the bacteria of the tree and soil can then convert to calcium carbonate, the main component of stones such as limestone and chalk.

Carbon in mineral form can remain in the soil much longer than in the organic matter of the tree. Trees known to store carbon in this way include Iroko Tree (Excelsa Militia), which grows in tropical Africa and is used for wood, but does not produce food.

Now Mike Rowley at the University of Zurich in Switzerland and his colleagues have discovered that three species of figs from the county of Samburu in Kenya can also do calcium carbonate from Co₂

“A large part of the trees becomes calcium carbonate above the ground,” explains Rowley. “We [also] See entire root structures that have almost turned to calcium carbonate in the soil where it should not be, at high concentrations. »»

The team first identified the species of fig trees that produce calcium carbonate by spurting low hydrochloric acid on trees and in search of bubbles – a sign of co₂ Released from calcium carbonate. Then, they measured how far they could detect calcium carbonate in the surrounding soil and analyzed tree samples to see where in their calcium carbonate trunks was produced.

“What was really a surprise, and I’m always a little in shock, is that the [calcium carbonate] had really gone much more deeply in the wooden structures than I was expecting, “said Rowley, who will present work at the Goldschmidt conference in Prague, the Czech Republic, this week.” I expected it to be a superficial process in cracks and weaknesses in the structure of wood. “

Researchers will have to do more work to calculate the quantity of carbon that trees store, as well as the amount of water they need and how resilient they are in different climates. But if the figs can be incorporated into future reforestation projects, then they could be both a food source and a carbon well, explains Rowley.