Interviewed: A. Aldrie Amir, mangrove ecologist (aldrie[at]ukm.edu.my)

(Photo: Mangrove forest at Matang, Perak, by A. Aldrie Amir)

ALL FORESTS capture and store carbon, but mangrove forests do it better, says mangrove specialist Aldrie.

Plants absorb carbon dioxide from the air to produce sugars. As they grow, plants store the carbon in their leaves, branches, trunk, roots, and even into the soil.

And when plants breathe or decompose, they gradually release their stored carbon.

But when humans burn or cut trees, we unleash a rapid and enormous release of carbon into the air.

Because excessive carbon dioxide has and continues to cause global warming, scientists have been advocating for reducing carbon emissions.

Here’s where mangroves can help, says Aldrie. 

Along with salt marshes and seagrass meadows, mangroves are marine ecosystems that can store carbon better than forests on land, he says. Carbon stored in coasts and seas is called blue carbon.

Malaysia has one of the largest mangrove areas worldwide. This gives the country a promising way to mitigate against climate change, says Aldrie.

Compared to tropical land forests, mangroves can store about 5 times more carbon per area, due largely to its soil.

While inland forests store most of their carbon in leaves and roots, mangroves keep 60% of theirs in the soil. 

Mangroves grow in wet soil with higher clay content. This environment can retain organic material – and thus store carbon – longer than the sandy soil typical of tropical inland forests.

Aldrie adds that the mangrove tree roots also have special structures that grow upward. Such ‘outgrowths’ inadvertently trap organic material well and can preserve carbon in the submerged soils. 

Also, mangrove sediments are always building up with run-offs from rivers and land. Oceanic particles that come in the tides also pile up.

This dynamic process creates thick sediments in the mangroves that hold a lot more carbon than the soil of inland forests.

Mangrove forests grow where rivers flow into the seas. In this unique confluence of freshwater and saltwater, nutrient levels are high and biodiversity thrives.

These conditions make mangroves a very productive ecosystem that captures more carbon from the air and stores it.

Finally, the animals that live in mangroves also help capture carbon in what Aldrie calls a “co-working relationship” with the mangrove trees.

He shares the example of leaf-eating crabs that patch their barrows with bits of leaves.

[Edited by YH Law and SL Wong]

Lucy Wong (@lucy_cfc) is a Macaranga Sprouts journalist. We thank the supporters of the Sprouts initiative who made this story possible. Lucy Wong reported for this article during her time in Rimbun Dahan’s Conservation Research Writing Residency.

Further Reading

C.H. Liu et al. 2017. Carbon stock evaluation of selected mangrove forests in Peninsular Malaysia and its potential market value. Journal of Environmental Science and Management 20: 77-87.

M. Mokhtari et al. 2016. Effects of fiddler crab burrows on sediment properties in the mangrove mudflats of Sungai Sepang, Malaysia. Biology 5: 7.

Z. Hemati et al. 2014. Rate of carbon storage in soil of natural and degraded mangrove forest in Peninsular Malaysia. Clean Soil Air Water 43: 614-619