Assessment of nitrogen reduction by constructed wetland based on InVEST: A case study of the Jiulong River Watershed, China.

The Jiulong River watershed (JRW) in southeast China includes livestock breeding and agriculture, leading to large amounts of non-point source pollution. Nitrogen (N) reductions were simulated and mapped using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) under scenarios that were built considered both constructed wetlands (CWs) and climate change, which are not common in the literature on ecosystem services assessments. The results showed that the amount of N exported from non-point sources within the JRW was 12,569 t·yr-1. The areal N load was relatively higher in the north, while more N exported in the southeast. Constructed riparian wetlands can intercept and reduce the N loads that enter water bodies, but climate change may be a factor driving the deterioration of water quality. The methodology can be generalized to reduce other contaminants, and provides a tool for decision-makers to weigh the costs and benefits of urbanization and conservation.