TDA-IME Project Final Report June, 2013 For the four countries represented in both the South China Sea region and Indochina (Cambodia, Malaysia, Philippines and Viet Nam) the per hectare values range from USD 882 to 3,643, with a total resource value of USD 2.15 billion per annum (from Table 17). However, with the exception of a value for coastal protection in Thailand, these estimates are of the direct value of mangrove goods only; and, moreover, they are believed to be conservative (J. Pernetta pers. comm.). They are, however, quite consistent with Dixon’s (1989) pioneering estimate that the average forestry and fishery benefits alone from mangroves are USD 500 to 2,500 per hectare per year. The UNEP (2007) study is also valuable because it provides a framework (as in Table 17) for assessing mangrove goods and services specifically in the Indochina region. Table 17 also reveals that there is a lack of economic data for many even quite common mangrove products in some countries; and data is even more deficient in relation to the value of mangrove services. Following the 2004 tsunami, and with the apparently increasing frequency and severity of severe weather events, plus other impacts caused by climate change, the need to reconsider and improve on the indirect and non-use value estimates for mangroves has become a widely recognized priority in coastal development, but actual progress has been slow. Studies before the Asia tsunami considered that the storm protection function of mangroves had a value of around USD 50 per hectare in Viet Nam (Tri et al., 1998) and USD 80 in Sri Lanka (Batagoda, 2003). Whereas, Sathirathai (1998) put the value of mangrove coastline protection and stabilization in Thailand at USD 3,000/ha/year; and the carbon sequestration value at USD 100/ha/year. A much higher carbon sequestration value of USD 1,810 ha/year was assumed for the mangroves on the west coast of Peninsular Malaysia (MPP-EAS, 1999). It is clearly difficult to apply such widely varying economic estimates to give a meaningful overall estimate of mangrove ecosystem value in Indochina. Non-use values of mangroves are even harder to quantify and the reliability of methods based on the concept of “willingness to pay” have a number of short-comings (e.g. Turner et al., 1994). The MPP-EAS (1999) study in Malaysia applied a non-use value for mangroves of USD 11,040 per ha per year, while Bann (1999) derived an estimate of almost USD 7,500 per hectare per year for the non-use values specifically for the mangroves in Johor. Of particular relevance to the TDA and priorities for a future Strategic Action Plan, Salem and Mercer (2012) advise that future valuation studies should also report on the health of the mangroves, since this will strongly influence their true economic value. Similarly, Salem and Mercer note the importance of describing the management system, e.g. for forestry or fisheries production, as obviously this has a major bearing on the yields (and therefore values) of mangrovederived goods like wood, fish and shellfish. Their recommendations fit well with those given earlier in this report that qualitative assessments of mangrove forests should be made, rather than only areal estimates. For both ecological integrity and economic valuation reasons, mangrove habitat quality must be investigated and reported on a transboundary scale. Assessing Mangrove Vulnerability to Climate Change In the longer term, reducing the impact of global climate change requires global action to address its causes, particularly in relation to CO2 emissions. Mitigating the ecological effects of climate change, in contrast, depends on local to regional action based on an understanding of the type of threats to the natural environment, plus assessment of the relative vulnerability of different areas and ecosystems to those threats. Appropriate management action can then follow. The impact of climate change on mangroves in different locations will depend on the environmental setting, plus other factors such as tidal range, sedimentology, salinity regime, community composition, and shore profile (Ellison 2012). In most areas, sea level rise is likely to have the greatest impact. Key factors to take into account in any assessment of climate change in coastal areas are relative sea level rise (RSLR), sedimentation rate, and shore topography. 88
Transboundary Diagnostic Analysis of Indochina Mangrove Ecosystems
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