An international study has focused on African fig trees capable of immobilizing carbon dioxide in mineral form within their wood. Via the oxalate-carbonate pathway, some of the captured CO2 ends up converted into calcium carbonate, a solid compound similar to chalk.
The research, carried out in Kenya with three species of Ficus, identified unexpected deposits of calcium carbonate on the surface of the trunk and inside the wood. Among the species analyzed, Ficus wakefieldii It showed particularly notable efficacy, opening the door to applications in agroforestry and soil management.
What the research says
The analysis detected calcium carbonate in logs and wood, indicating a deeper and more persistent carbon fixation than previously thought, beyond the organic carbon stored in biomass that can degrade rapidly.
The mechanism is based on the oxalate-carbonate pathwayFig trees produce calcium oxalate crystals, which can then be transformed into calcium carbonate, a stable mineral that remains in the environment for a long time.
In this conversion the following play a decisive role: soil microorganisms, which catalyze the conversion of oxalate to carbonate when plant tissue decomposes. Their role is key and opens up new lines of research to understand the conditions and rates of this process.
According to the researcher Mike Rowley, select trees with this ability would allow a double carbon storage (biomass and minerals), which could amplify the benefits of agroforestry practices in different landscapes.
Implications for agroforestry and climate
The identification of species with the greatest mineralization potential suggests that a more effective agroforestry design could increase carbon capture without sacrificing the usual ecosystem services (shade, biodiversity or production).
In addition to fixing carbon, the calcium carbonate tends to generate a more alkaline and fertile soil, improving nutrient availability and counteracting acidification processes that affect agricultural productivity.
The study recommends identify other species capable of this path and design planting strategies that maximize mineralization, always accompanied by monitoring to evaluate the actual accumulation in different types of soils.
However, they persist, knowledge gaps: Data are lacking on the extent of the phenomenon in other Ficus and other families, the environmental conditions that favor it, and its long-term stability in different climates and soils.
Fig trees convert CO2 into minerals during photosynthesis
During the photosynthesisFig trees absorb atmospheric CO2. Some of that carbon forms calcium oxalate crystals in different tissues of the plant.
When leaves, bark or wood containing oxalate decompose, microbial communities are involved that transform oxalate into stable calcium carbonate, a mineral that does not break down easily.
This carbonate alkalizes the environment and may persist for decades or centuries, unlike organic carbon, which is usually reincorporated into the atmosphere after decomposition.
The oxalate-carbonate pathway offers a natural sink which complements biomass storage, without requiring complex technologies and with added benefits for soil health.
This work reinforces the idea that certain fig trees that mineralize carbon can play a relevant role in productive landscapesWith more evidence and appropriate species selection, agroforestry can gain climate efficiency without losing agronomic functionality.
