Fig bushes might profit local weather by turning carbon dioxide into stone

Some fig bushes can convert surprisingly massive quantities of carbon dioxide into stone, guaranteeing that the carbon stays within the soil lengthy after the tree has died. Which means fig bushes planted for forestry or their fruit might supply further local weather advantages by way of this carbon-sequestration course of.

All bushes take up CO₂ from the air, and most of that carbon sometimes finally ends up as structural molecules used to construct the plant, similar to cellulose. Some bushes, nevertheless, convert CO₂ right into a crystal compound referred to as calcium oxalate, which micro organism within the tree and the soil can then convert to calcium carbonate, the principle part of stones like limestone and chalk.

Carbon in mineral type can keep inside soil for for much longer than it may within the tree’s natural matter. The bushes identified to retailer carbon on this approach embody the iroko tree (Milicia excelsa), which grows in tropical Africa and is used for timber, however doesn’t produce meals.

Now, Mike Rowley on the College of Zurich in Switzerland and his colleagues have discovered that three species of fig tree native to Samburu County in Kenya may also make calcium carbonate from CO_2.

“A big a part of the bushes turns into calcium carbonate above floor,” says Rowley. “We [also] see whole root buildings which have just about turned to calcium carbonate within the soil the place it shouldn’t be, in excessive concentrations.”

The crew first recognized the fig tree species that produce calcium carbonate by squirting weak hydrochloric acid onto the bushes and searching for bubbles – an indication of CO₂ being launched from calcium carbonate. Then, they measured how distant they may detect calcium carbonate within the surrounding soil and analysed samples of the bushes to see the place of their trunks calcium carbonate was being produced.

“What was actually a shock, and I’m nonetheless type of reeling from, is that the [calcium carbonate] had actually gone far deeper into the wooden buildings than I anticipated,” says Rowley, who will current the work on the Goldschmidt Convention in Prague, the Czech Republic, this week. “I anticipated it to be a superficial course of within the cracks and weaknesses throughout the wooden construction.”

The researchers might want to do extra work to calculate how a lot carbon the bushes are storing, in addition to how a lot water they want and the way resilient they’re in several climates. But when fig bushes might be included into future reforestation initiatives, then they may very well be each a meals supply and carbon sink, says Rowley.