The forgotten ecosystems vital to the carbon cycle

Mangroves at Hinchinbrook Channel. Image: Tim Simmonds.
Mangroves at Hinchinbrook Channel . Image: Tim Simmonds.

Mangroves are just as productive and extensive as rainforests and are a vital part of the Earth's carbon cycle, but they are often the forgotten ecosystem, not valued and so not properly looked after.

A new book by AIMS researcher Dr Daniel Alongi, The Energetics of Mangrove Forests (published by Springer), is a comprehensive examination and unique synthesis of these crucial biological systems that inhabit the harsh fringe areas between land and sea and exhibit characteristics of both land-based and marine ecosystems. It also provides a status report on how mangroves are faring in a time of rising and shifting populations and changing climate.

An analysis of carbon flows through mangroves showed that these forests are just as productive as rainforests and also process a disproportionate amount of carbon. Although they only cover 0.1 per cent of the Earth's surface, they process five per cent of carbon in the atmosphere.

However, in many parts of the world, mangrove destruction continues unabated in this century, at an annual global rate of one to two per cent. Since mangroves occur mostly in tropical regions, which are inhabited largely by poor people, mangrove ecosystems face constant threats. Losing a resource before its importance is fully established is a concern for coastal sustainability. For example, at present very little is known about the link between mangroves and fisheries, although it is clear that there is a link. Mangroves have a number of known benefits as well, such as protecting coastlines from erosion and, in some cases, weakening the destructive energy of waves, including tsunamis.

The research outlined in Dr Alongi's book will inform decision making in countries that have mangrove ecosystems, leading to preservation of remaining mangrove forests and reforestation in places where mangroves have been cleared.