The feasibility of mangrove REDD+ projects in the Western Indian Ocean: Linking mangrove conservation and climate change adaptation to the global carbon markets

Of all the biological carbon (i.e., green carbon) captured in the world, >50% is captured by marine living organisms (i.e., blue carbon). Mangroves, salt marshes and seagrasses form much of the earth’s blue carbon sinks and store comparable amounts of carbon per year to all other plant biomass on land. Blue carbon habitats will play a critical role in mitigating climate change, not only because of the size of the pools which they lock-up, but also because they provide a wealth of other ecosystem goods (e.g., food; fuel; construction material; medicine) and services (e.g., storm protection; barriers to erosion; breeding grounds and nurseries; water filtration) essential to the long-term well-being and climate change adaptability of increasingly vulnerable coastal communities. The significant role that coastal habitat loss has on global greenhouse gas emissions and the important role these habitats play in climate change adaptation are becoming increasingly recognized at an international level (Laffoley et al., 2009; Nellemann et al., 2009; Gordon et al. 2011; Pendleton et al. 2012; Ullman et al. 2012). There is a growing international movement to establish a REDD+ (Reducing Emissions from Deforestation and Degradation plus other measures to restore, enhance, and conserve carbon stocks) mechanism for blue carbon habitats similar to that existing for terrestrial forests. There is also an urgent need to include coastal, marine carbon in National Inventory Submissions – the mandatory national accounting of greenhouse gas emissions that countries must submit under the United Nations Framework Convention on Climate Change (UNFCC) (Thompson, 2009).
With an estimated 2,800 km2 of mangroves in 2005 (Giri and Muhlhausen, 2008), Madagascar is seemingly blessed with significant blue carbon assets. The generation of carbon credits through the conservation and restoration of such habitats could make a critical contribution to poverty alleviation and biodiversity conservation in coastal areas. However, following global trends, these forests are being rapidly degraded and deforested. In particular, Madagascar’s mangroves are threatened by over-exploitation for charcoal and timber, conversion for agriculture and hyper-sedimentation from upstream deforestation.
In Madagascar, as elsewhere, there is a critical lack of technical capacity to quantify mangrove carbon, as well as to establish projects that will conserve them for the generation of carbon credits. The accurate quantification of carbon sequestration by mangroves is fundamental to establishing carbon offsetting projects based on their conservation, restoration and sustainable-use, and ultimately in placing financial value on them. The true value of mangroves needs to be accounted for and weighed against alternative uses, such as conversion for agriculture.

The exact nature of carbon fluxes between mangroves and their surrounding environment is complex and remains an active subject of research (Kristensen et al., 2008). While the sequestration of carbon in mangroves can vary greatly from site to site, relatively few studies of carbon have been undertaken in the WIO in comparison to other major mangrove regions in the world (e.g., Indonesia, Malaysia). While numerous studies have measured above-ground biomass in mangrove trees (Twilley et al., 1992; Saenger, 2002; Komiyama et al., 2005; Alongi, 2009; Kauffman & Cole, 2010), few have quantified both above- and below-ground pools (i.e., Adame et al. 2013; Chen et al. 2012; Donato et al., 2011; Kauffman et al., 2011; Donato et al., 2012; Matsui et al. 2012; Ray et al. 2011). However, it is the deep, organic-rich soils (i.e., below-ground pools) that are thought to contain the vast majority of C stocks (Golley et al., 1962; Matsui, 1998; Fujimoto et al., 1999).
Carbon offset project developers must adhere to methodologies approved by issuers of carbon credits to establish the net CO2 sequestered by a project. This must be done to provide ex ante (pre-project) and ex poste (actual) CO2 reductions.
Existing approved methodologies are designed for terrestrial forests and are not entirely appropriate for the development of mangrove carbon offsetting projects. Therefore, the development and validation of baseline and monitoring methodologies that take into account the unique characteristics of mangroves is critical for effective long-term conservation, restoration and sustainable-use.

1. Contribute to the development of REDD methodologies specific to mangroves
2. Build local capacity to undertake ecological and carbon stock measurements and establish REDD+ projects
3. Demonstrate the value of Madagascar’s mangroves in mitigating climate change
4. Assess the feasibility of establishing mangrove REDD+ projects within the Western Indian Ocean region
5. Catalyse the development of a mangrove REDD+ project