Mangroves are salt-tolerant trees or shrubs found along low-energy, tidal shorelines in tropical and subtropical areas. Mangrove marsh, including mangrove communities and their habitats, support a variety of forage resources for commercially and recreationally important birds, fishes and invertebrates. They also provide a wide range of ecological services such as purification of polluted gulf waters, protection against floods and hurricanes, reduction of shoreline and riverbank erosion, control of air components, and maintenance of biodiversity. These services enable, promote, and sustain economic activities in coastal areas throughout the tropics and subtropics. However, the economic value of natural products and ecosystem services generated by mangrove forests is generally underestimated. As a consequence, the deforestation rate of mangrove forests is rising rapidly due to large-scale development activities such as agriculture, aquaculture, forestry, salt extraction and infrastructure. This makes the evaluation of the ecologic services value of mangroves extremely important.
MaiPo marsh is the largest remaining and most important wetland in Hong Kong. This paper applies a suite of ecological economic methods, including marketing price method, shadow price method, substitute method, fuzzy mathematics method, and questionnaire investigation method, to evaluate the ecologic services value of the MaiPo marsh. Since it is not possible to place a monetary value on all relevant services, this paper considers the most important services: material output, control of air components, sewage purification, tourism and education function, and maintenance of biodiversity. Evaluation of the results show that material output is valued at HKD|S11.38×106; control of air components is valued at HKD|S14.54×10⁶; sewage purification is valued at HKD|S141.9×10⁶; tourism and education is valued at HKD|S 23.37×10⁶; and maintenance of biodiversity is valued at HKD|S 8.05×10⁶. The total ecologic services value of the Mai Po marsh in 2003 is HKD|S208.79×10⁶. The paper also discusses briefly the shortcomings of present economic valuation methods and suggests improving future studies by increasing ecological knowledge and advancing monetary valuation methods.