Modeling hydrological ecosystem services and tradeoffs: a case study in Baiyangdian watershed, China

Policy makers and scientists consider that land use strategies are designed to provide direct benefits to people by protecting vital ecosystem services. However, due to lack of information and evaluation methods, there is no effective and systematic tool for assessing tradeoffs between direct human benefits and ecosystem services. Land use changes influence ecosystem properties, processes and components, which are the basis for providing services. Five alternative land use scenarios (no conversion of agricultural lands, no urban expansion, agricultural expansion, forestry expansion, and riparian reforestation) were modeled for the Baiyangdian watershed, China, a densely populated, highly modified watershed with serious water shortage and pollution problems. The model InVEST (Integrated Valuation of Ecosystem Services and Tradeoffs) is designed to inform decisions about natural resource management, with an aim to align economic forces with conservation. Three ecosystem services (agricultural production, hydropower production, and water quality) were modeled to balance direct benefits and hydrological ecosystem services using InVEST. The results showed that: hydropower production was the greatest in the forestry expansion, but the lowest in agricultural expansion; agricultural production was reduced the most in forestry expansion, while retained the most in riparian reforestation. Riparian reforestation also provided the highest N and P retention and lowest N and P exportation. Riparian reforestation was the optimal land use strategy, since it protected and enhanced the vital ecosystem services without undermining direct human benefits. This research presents an initial analytical framework for integrating direct human benefits and ecosystem services in policy planning and illustrates its application. Although there are important potential tradeoffs between ecosystem services, this systematic planning framework offers a means for identifying valuable synergies between conservation and development.