Mangrove forests are particularly found in tropical and subtropical regions within 300 of the equator. These tidal areas, such as estuaries and marine shorelines, are frequently inundated with salt water. Strongly in decline, mangrove forests occupy about 15.2 million hectares of tropical coast worldwide: across Africa, Australia, Asia and America (Spalding et al. 2010).
Intrinsic Values of Mangroves
Mangrove forests provide protection and shelter against extreme weather events, such as storm winds and floods, as well as tsunamis. Mangroves absorb and disperse tidal surges associated with these events – as indicated by Hirashi and Harada (2003), a mangrove stand of 30 trees per 0.01 hectare with a depth of 100 m can reduce the destructive force of a tsunami by up to 90%.
Mangrove forests are rich in biodiversity providing a habitat for wide varieties of animal and plant species. They are dynamic areas, rich in food. Live and decaying mangrove leaves and roots provide nutrients that nourish plankton, algae, fish and shellfish. Many of the fish caught commercially in tropical regions reproduce and spend time in the mangroves as juveniles or adults. Mangroves are also home to many birds and mammals – such as mangrove monkeys in South Asia.
Map: Global Mangrove distribution (Giri) - click to enlarge
Traditional economic activities vary from fishing and gathering of crustaceans to usages of the trees for timber or tannin production. Research by Barbier (2007) concluded that the economic annual value of just one hectare of mangrove forest (by adding the values of collected wood and non-wood forest products, fishery, nursery and coastal protection against storms) is $12,392.
Next to economic value, mangroves also bear great cultural significance for communities, such as the Concheras (shellfish-gatherers) in South America, as their identity is strongly related to the ecosystem they live in.
Storage of carbon in mangroves takes place through accumulation in living biomass and through burial in sediment deposits. With living biomass typically ranging between 100-400 tonnes/ha, and significant quantities of organic matter being stored in the sediments, mangroves rival the sequestration potential of rainforests.
Mangroves under threat
Globally, half of all mangrove forests have been lost since the mid-twentieth century, with one-fifth since 1980 (Spalding et al. 2010). Conversion into shrimp farms causes 25% of the total destruction, according to UNEP (Botkin and Keller, 2003), happening mostly in Southeast Asia and Latin America. Other drivers of mangrove destruction are wood extraction, climate change and industrial development such as harbours and tourism.
Wetlands International aims to reverse the rapid loss of mangrove forests along with working towards the achievement of sustainable development that enhances the many benefits provided by mangroves. In particular, we support local communities in West Africa (Guinea Bissau, Sierra Leone), Asia (India, Indonesia, Malaysia and Thailand) and Latin America (Panama) in restoring these invaluable ecosystems. Over the past decade we have restored thousands of hectares of mangrove forests and we are working to address the drivers of mangrove destruction. Read more on what we do