Integrated ecosystem services-based calculation of ecological water demand for a macrophyte-dominated shallow lake

Abstract

Macrophyte-dominated shallow lakes are one of the commonest freshwater wetlands in plain area, and composed of lake, marsh, and terrestrial land. They are, however, facing great ecological risks of serious pollution and wetland degradation caused by the shortage of ecological water demand. Baiyangdian is the largest shallow lake in northern China. It is of great importance to ecosystem services in Xiongan New Area, China, providing food production, climate regulation and other functions. Water storage in Baiyangdian comprises components of lake, marsh and terrestrial land, each of which supplies a different ecosystem service value (ESV). As a result, the total ESV of a macrophyte-dominated shallow lake changes according to water storage fluctuation. In this study, we estimated the total and individual land ESVs (lake, marsh, and terrestrial land) of the Baiyangdian. We also quantified the relationship between ESV and water storage in the macrophyte-dominated shallow lake, taking water level as the indicator. The optimum water level varied, corresponding to the highest ESV of each type of land, and an optimum water level of 8.2 m was identified as achieving the highest total ESV of the Baiyangdian (6.697 billion yuan). We also divided ecosystem services into four functional categories: provisioning, regulating, supporting, and cultural and found these components also changed with water storage changes in the macrophyte-dominated shallow lake. Fluctuation in the total ESV was attributed mainly to the marshland because of its huge supply capacity for support and cultural services. An optimum water level range of 7.9–8.5 m existed where ESV was most balance among different functional categories. After considering the functional and land cover components of total ESV of the Baiyangdian, we recommend an optimum water level of 8.2 m, and emphasize the importance of including ESV in calculations of ecological water demand.