Mangrove offers Asian nations a sustainable resource

Asia's mangrove swamps may offer the region a future carbon trading option and pollution cleaning solution.

Two new sets of research show that the value of mangrove swamps to the environment has been vastly underestimated and that there are solid arguments for including such habitat in carbon-trade schemes similar to REDD+.

A paper presented by US scientists in Proceedings of the National Academy of Sciences (PNAS), shows that the carbon capture of mangrove areas has been vastly underestimated. It says that on average they can capture carbon five times more efficiently than rainforests and it was imperative to include them in carbon trading structures.

Data indicate that mangroves are among the most carbon-rich forests in the tropics, containing on average 1,023 Mg carbon per hectare. Steve Buoillon's paper Carbon cycle: Storage beneath mangroves,  reported, “Combining our data with other published information, we estimate that mangrove deforestation generates emissions of 0.02–0.12 Pg carbon per year—as much as around 10 per cent of emissions from deforestation globally, despite accounting for just 0.7 per cent of tropical forest area”.
 
However, as the research points out, destruction of mangrove habitat releases more carbon than rainforest and it's disappearing faster than rainforest. Research shows that globally mangrove forests have declined by 30–50 per cent over the past half century as a result of coastal development, aquaculture expansion and over-harvesting.

In parts of Asia this destruction is even higher. Last year Indonesia's then Environment Minister, Gusti Muhammad Hatta, said that of the nation's 9.36 million hectares of mangrove forests, 48 per cent were “moderately damaged” and 23 per cent “badly damaged”. In other words 71 per cent of mangrove was affected.

The impact of climate change is highlighted in the second new piece of mangrove research, from France's Institute of Development Research (IRD) and regional partners. Working in New Caledonia, which is the world's third largest nickel producer, they discovered that mangrove forests act as useful filters for toxic heavy metals spilled by the mining industry, preventing them from contaminating waterways.

The IRD researchers point out that spills from mining waste pits are likely to get worse because of climate change since tanks are more likely to overflow in typhoons and heavy storms, which are becoming increasingly common.

For forward thinking governments the two reports, along with a long list of others, should offer a variety of sustainable but economically profitable opportunities. The mangrove environment has been shown as rich in biodiversity bringing rich fishing. Research has also shown mangroves protect coastal communities from tsunamis, typhoons and flooding, which is becoming an increasing problem as climate change accelerates.

Already Chinese scientists have called on their government  to exploit the carbon sink of mangrove forests. In 2010 three Chinese scientists, led by Jiang Gaoming, chief researcher at the Chinese Academy of Sciences, argued that replanting mangrove in half of China's 347,000 square kilometres of saline soil could lead to 100 million tonnes of carbon dioxide absorption.

They reported that China's mangrove forest area had fallen from 500 to 150 square kilometres over the past 60 years as a result of reclamation and felling, with 15 per cent of construction in coastal areas taking place on reclaimed land.

Many of the rapidly industrializing nations across Asia have coastal environments suitable for mangrove, which can bring numerous benefits: cleaning already contaminated water, protecting local communities from increasingly common natural disasters and eventually earn cash for carbon credits. And the bonus is a healthier biodiversity.