Twisted and contorted fingers of mangroves roots are holding onto a rich, black 'climate-stabilizing' treasure, according to just-published research in the latest Nature Geoscience.

The thick muds that characterize these unique swamplands - found along coasts and estuaries in the tropics - are a major store of carbon that would otherwise enter the atmosphere, and further prod global warming.

That makes mangrove swamp conservation an even higher priority, say researchers from the US Forest Service in Durham, New Hampshire.

They are found across the tropics in some 100 countries, and are home to a wide range of specially adapted animals - from crabs and snakes to proboscis monkeys and crocodiles.

With the area of mangrove forests halving over the last 50 years, understanding the implications for carbon release is as important as the considerable biodiversity loss.

So the team, including ecologist J. Boone Kauffman, looked at 25 sites from across the tropics - from Micronesia to Bangladesh. They looked at how much carbon was being stored in the biomass of the plants themselves - as well as in the muddy soils clasped in their roots.

What they discovered was that mangrove forests hold onto much more carbon, than equivalent areas in tropical upland, temperate or boreal (northern) forests. This carbon was often found in an organic-rich layer of mud, over a foot below the surface. This layer was thickest for those mangroves growing in estuaries - but less pronounced in those fronting the sea directly.

Although they make up only 1% of all tropical forest areas, the thickness of this carbon-rich layer means mangroves hold as much as a quarter of the carbon of tropical peat lands. Because mangrove forests are being lost at such a high rate, that means they could contribute as much as 10% of all CO2 releases caused by forest destruction.

That adds considerable weight to the cause of protecting these fascinating muddy-interfaces, between land and sea. Robert Jackson, another ecologist, from Duke University, North Carolina, observed that '' mangrove forests are important for diversity, for coastal stability and for carbon, based on this paper. It gives another justification for preserving mangrove forests.''