2023-09-21 17:14:57
MADRID, 21 Sep. (EUROPA PRESS) –
Arid lands, like deserts, could be an answer to the problem of carbon sequestration, a group of plant experts argues in an article in ‘Trends in Plant Science’.
Reducing CO2 levels in the atmosphere requires not only reducing emissions, but also capture and store excess volumes of carbon already emitted.
The authors argue that we could transform arid ecosystems into efficient carbon sequestration systems with improved soil health, higher photosynthetic efficiency and greater root biomass by engineering ideal combinations of plants, soil microbes and soil type to facilitate a natural biogeochemical process called the oxalate-carbonate pathway to create carbon sinks under the ground.
“Greening deserts by restoring ecosystem functions, including carbon sequestration, should be the preferred approach,” writes the research team, led by lead author and plant scientist Heribert Hirt of King Abdullah University. of Science and Technology, in Saudi Arabia–. The advantage of recovering arid regions for greening and carbon sequestration is that “they do not compete with land used in agriculture and food production.”
The method takes advantage of plants adapted to arid areas that produce oxalates, ions that contain carbon and oxygen and that may be familiar to you if you are unlucky enough to suffer from kidney stones or gout. Some soil microbes use oxalates as their sole carbon source and, in doing so, excrete carbonate molecules into the soil.
Carbonate usually decomposes quickly, but if these plant-microbe systems are grown in alkaline, calcium-rich soils, the carbonate reacts with calcium to form stable calcium carbonate deposits.
Carbon circulates naturally between the atmosphere, oceans and terrestrial ecosystems, but human action has caused the accumulation of excess CO2 in the atmosphere. Even if we can reduce CO2 emissions, the researchers write that the “climate effects of elevated CO2 “They will remain irreversible for at least 1,000 years unless CO2 can be sequestered from the atmosphere.”
Trees are considered an ideal system for carbon capture, but reforestation competes directly with agriculture for arable land. In contrast, arid lands, which constitute approximately one third of the land areas, are not used for agriculture.
Currently, arid ecosystems support very little plant life, with lack of water being the greatest limiting factor. However, some plants have adapted to arid life by developing different mechanisms. to cope with the lack of water and extreme temperatures.
Some plants adapted to aridity have special root systems to reach deep into the soil and exploit hidden water sources, while others use different forms of photosynthesis that allow them to minimize water loss during the hottest hours of the day.
Others, so-called “oxalogenous” plants, produce large amounts of oxalates that they can convert into water in times of drought. Some of the carbon from these oxalates is deposited underground as carbon stores when oxalogenic plants grow under certain conditions, and it is this mechanism that the authors want to exploit for carbon sequestration.
“Taken together, in this form of carbon sequestration, one in sixteen photosynthetically fixed carbon atoms could be sequestered in carbonates“, write the authors.
Amplifying this natural biogeochemical process in drylands could turn these currently unproductive and degraded ecosystems into carbon sinks with healthier soils and plants, the authors say. They suggest starting with “fertility islands,” small pockets of greening habitat from which plants and microbes can spread to form a carpet of vegetation.
The authors estimate that these approaches could lead to significant increases in carbon sequestration in both plants and soil in less than ten years.
However, they point out that the success and speed of the proposed method will depend on the growth rate of the plants (which tends to be slow in conditions of water scarcity) and “It will also depend on the financial and political means to apply this technology in various arid countries.”
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