Economic Valuation of Selected Indirect Uses of Mangroves Damaged by the Solar I Oil Spill in Guimaras Island, Philippines A Benefit Transfer Approach


by: Gay D. Defiesta


Mangroves forests are important ecosystems for the goods and services they provide humanity including timber support to fisheries, carbon sequestration, protection from storms and tsunamis and even recreation among others. The total economic value of mangroves includes direct, indirect, option and non-use values. Unfortunately, mangrove ecosystems face intense pressure due to anthropogenic activities. Among those that severely damage mangroves forests worldwide are oil spills.

This study values the damage of the Solar I oil spill on mangroves in Guimaras last August, 2006 particularly indirect use values of four selected ecosystem functions namely litterfall, nursery, storm protection and soil erosion prevention functions. These actual and potential losses of the damage were estimated using benefit transfer method. Actual losses based on tree mortality of 0.97 hectare is equivalent to Php92,255 for the initial year. Potential losses range from PhP 3.99 million to PhP 6.6 million under the assumed best case scenario of 6.45 hectares or 1% damage of mangrove cover and PhP 59.8 million to PhP 98.7 million under worst case assumption of 15% damage.

The figures presented in this study could be viewed as indicators of the social loss arising from the damaged mangroves caused by the oil spill and should be appreciated in terms of the insight they provide on the extent of this loss. The study recommends that monitoring of actual mangrove damage should be conducted to serve as basis for original valuation studies. It is also suggested that original valuation studies on a wider range of ecosystem services of mangroves in the Philippines be done to provide basis of their total economic value.