Research by a team of Kenya, US, Australia and Swiss-based scientists has identified a unique feature of three species.
Presented this summer at the Gold-schmidt conference in Prague, the trio of fig trees, all of which are native to East Africa, are capable of drawing in carbon dioxide from the atmosphere and storing this as calcium carbonate ‘rocks’ in the surrounding soil.
Certain trees also turn sequestered carbon emissions into calcium oxalate crystals. When the flora begins to decay, these crystals are converted into a specialised bacteria or fungi into calcium carbonate. This is the same mineral as limestone or chalk, increasing the availability of nutrients which nature relies upon. The inorganic compound also typically has a longer lifespan in the soil. As such, it becomes a much more efficient method of storing the greenhouse gas.
‘We’ve known about the oxalate carbonate pathway for some time, but its potential for sequestering carbon hasn’t been fully considered,’ said Dr Mike Rowley, Senior Lecturer at the University of Zurich. ‘If we’re planting trees for agroforestry and their ability to store CO2 as organic carbon, while producing food, we could choose trees that provide an additional benefit by sequestering inorganic carbon also, in the form of calcium carbonate.
‘As the calcium carbonate is formed, the soil around the tree becomes more alkaline,’ he continued. ‘The calcium carbonate is formed both on the surface of the tree and within the wood structures, likely as microorganisms decompose crystals on the surface and also, penetrate deeper into the tree. It shows that inorganic carbon is being sequestered more deeply within the wood than we previously realised.’
Image: Martin Angelov / Unsplash
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