Wise use of paddy rice fields to partially compensate for the loss of natural wetlands

This paper reviews the scientific information related to climate change impacts on wetlands and functions of human-made wetlands such as paddy rice field and treatment wetland are described to partially compensate for the loss of natural wetlands. Wetlands are among the world’s most productive environments and are cradles of biological diversity, providing the water and primary productivity upon which countless species of plants and animals depend for survival. Considerable evidence suggests that some global warming is occurring, which has important implications for wetland system as well as human life and wildlife. Direct effects of climate change on wetlands are likely to be accentuated by human induced changes that will increase stress to wetland ecosystems. The Ramsar Classification System for Wetland Type provides three broad categories: marine/coastal wetlands, inland wetlands, and human-made wetlands. Human-made wetlands are as important as natural wetlands, and the largest human-made wetland is a paddy rice field (130,000,000 ha) taking about 18% of total global wetland, which is second only to natural fresh wetlands. Paddy rice fields provide not only rice production for food, but also diverse multi-functionalities such as flood control, groundwater recharge, soil erosion control, water quality purification, air purification and cooling, wildlife habitat, amenity and social benefits. The economic value of multi-functionalities estimated by contingent valuation method (CVM) and travel cost method was in the range of U$ 9.75–11.46 billion, which is greater than the value of rice production itself in Korea. Unfortunately, there is an indication of decreased area in paddy rice field in Korea after 1990 showing about 20% decrease in 15 years. Another human-made wetland type is a constructed wetland for water purification, and thousands hectares of wetlands are scheduled to be constructed for reservoir water quality improvement in next 5 years in Korea, and their application is expected to be more common in near future. There is a growing consensus that wetlands are critically important ecosystems that provide globally significant social, economic and environmental benefits. Wise use of human-made wetlands is as important as conservation of natural wetlands, which can be a viable element to overall climate change mitigation and can partially compensate for the loss of natural wetlands.