Wetlands as natural assets

As the services of wetlands are uniquely related to hydrological processes, they result in a wide range of benefits to humankind. Although this facilitates the characterization of wetlands as natural assets, there are measurement problems. Because wetland services are nearly always non-marketed, they need to be explicitly valued to determine the trade-offs between development and conservation of wetlands. Two case studies, a floodplain in northern Nigeria and mangroves in southern Thailand, illustrate the issues involved. In the case of Nigeria, the natural capital is the river floodplain, and the trade-off is the upstream water diversion compared to the downstream flooding benefits to farming, fishery and forestry, as well as groundwater recharge. In the case of Thailand, the natural capital is the mangrove system, and the trade-off is the conversion to shrimp farms, as opposed to the mangrove benefits of locally harvested products, habitat-fishery linkages and storm protection.