Mangroves mitigate climate impacts

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A global restoration effort aims to protect mangroves - as a study reveals the extent of climate-related destruction.

This data highlights the delicate balance between wood-biodegrading organisms and fallen mangrove wood.

Mangrove forests play a vital role in the health of our planet. The trees and shrubs absorb a substantial amount of greenhouse gas emissions, help protect communities from rising sea levels and act as nurseries for baby fish.

These coastal forests are the second most carbon-rich ecosystem in the world, being able to store more than 1,000 tons of carbon in just one hectare - that’s about the size of a football pitch.

They do this by capturing the chemical element from the air and storing it in leaves, branches, trunks and roots. But despite environmental efforts to prevent the loss of these important ecosystems, they are still at risk.

Systems 

A new study, by the University of Portsmouth and facilitated by research organisation Operation Wallacea, has revealed how the stored carbon from atmospheric CO2 in large woody debris is processed by organisms.

The findings suggest climate breakdown can significantly impact this ‘blue carbon’ system - meaning carbon stored in coastal and marine systems.

Scientists from the University of Portsmouth analysed large woody debris (LWD) in four mangrove forests in Indonesia’s Wakatobi National Park with differing intertidal zones.

Each survey area had up to 8 sections (transects) - each revealing its own way of processing carbon.

In the upper reaches of the ecosystem, closer to land, the team discovered organisms typically found in tropical rainforests are breaking down fallen wood.

These include fungi, beetle larvae, and termites. Further towards the ocean, the LWD is being degraded more quickly by worm-like clams with calcium carbonate shells, known as shipworms.

Dissolve 

Two consequences of climate breakdown can affect the delicate process of fixed-carbon degradation in the mangrove forest. The first is rising sea levels, as the carbon cycle is driven by tidal elevation.

The second is an increase in ocean acidity caused by rising CO2 in the atmosphere, which can dissolve the shells of the marine organisms degrading the wood in the lower reaches.

This data highlights the delicate balance between wood-biodegrading organisms and fallen mangrove wood.

“This data highlights the delicate balance between wood-biodegrading organisms and fallen mangrove wood. Mangrove forests are crucial to mitigating climate change.

"Alterations to the breakdown of fallen wood in the forests will change the above-ground carbon cycles which may have an effect on mangrove carbon stores,” said the lead author of the study, Dr Ian Hendy from the University of Portsmouth’s School of Biological Sciences. 

Restoration 

Dr Hendy and his team hope to take part in large-scale mangrove forest restoration in Mexico.

The joint biodiversity initiative rePLANET is working exclusively with a group of scientists at Portsmouth, Brighton, Singapore, and CINESTAV to fund a series of PhD projects examining the innovative approaches being taken to preserve and protect forests.

Dr Simon Cragg, the study’s co-author, based at the University of Portsmouth, added: “The team's goal now is to use the findings from this study to guide large-scale restoration of mangrove forests across the globe."

Restoring mangroves not only helps mitigates climate impacts and support wildlife, but they provide food and livelihoods for millions of people around the world.

You can read more about why mangroves matter for people and the planet here. 

This Author 

Yasmin Dahnoun is an assistant editor for The Ecologist. This report was based on the Biodegraders of Large Woody Debris Across a Tidal Gradient in an Indonesian Mangrove Ecosystem study, published in Frontiers, and supported by experts from the University of Plymouth, Brighton University, the Eden Project, UK Centre for Ecology & Hydrology, and Estonian University of Life Sciences.

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