Mexican mangroves have been storing carbon for nearly 5,000 years • Earth.com

mangrove They have been known to thrive in conditions that most other plants cannot tolerate, such as in salty coastal waters. Many species have vertical, air-conducting roots that act like plunging when the tide is high, giving them the appearance of trees perched on stilts.

A new study led by University of California, Riverside (UCR) and University of California, San Diego (UCSD) has investigated how marine mangroves off the coast of La Paz in Mexico absorb and release substances such as carbon and nitrogen, through a process called biogeochemical cycling. Experts were amazed to discover that these mangrove forests have been quietly keeping carbon out of Earth’s atmosphere for nearly 5,000 years.

“What sets these mangrove sites apart is not that they are the fastest to store carbon, but that they have retained carbon for a long time,” said lead study author Emma Aronson, an environmental microbiologist at the University of California. “It’s storing carbon in larger volumes than most other ecosystems in the area.”

While the scientists expected carbon to be present in the peat layer below the forest – which consists of a mixture of submerged sediment and partially decomposed organic matter, which extends up to ten feet below the coastal water line – they did not expect the carbon to be 5,000 years old.

Because biogeochemical cycling is largely driven by microorganisms such as bacteria and fungi, the researchers set out to investigate which of these microbes thrive in the peat beneath the mangroves. The analysis revealed no fungi living there, likely due to the fact that very little oxygen – which the fungi need to break down carbon – can reach the deepest layer of peat.

While scientists have identified more than 1,100 species of bacteria that live under mangroves and that can operate in harsh environments with little or no oxygen, these microbes aren’t enough to break down carbon – which may explain the enormous potential of mangroves to safely store this dangerous gas. .

“The deeper you go into peat soil, the fewer microorganisms you find. Not much carbon there, or peat itself, can be broken down because it lasts so long,” said study co-author Mia Maltz, a microbial ecologist at the University of California. It is not easy to produce more of them or replicate the microbial communities within them.”

“These sites protect carbon that’s been around for thousands of years. Disturbing them will lead to carbon emissions that we won’t be able to fix any time soon,” added study lead author Matthew Costa, a coastal ecologist at the University of California, San Francisco.

“If we let these forests continue to function, they could retain the carbon they sequestered from our atmosphere, essentially permanently. Mangroves play an important role in mitigating the effects of climate change,” he concluded.

The study was published in the journal Marine Ecology Advance Series.

by Andrei IonescuAnd the Earth.com crew clerk