Combining paleolimnological proxies to understand the long-term social-ecological interactions: A case study in the Erhai basin, Southwest China.

Understanding social-ecological interactions is a major research priority for sustainable management. However, the scarcity in multi-decadal records represents a big gap in information that hinders the development of above research. In this paper, we propose a framework to explore the long-term dynamic mechanisms between social and ecological systems, and present a case study in the Erhai basin, southwest China. Using paleolimnological proxies to reconstruct the long-term trends of ecological changes, the social-ecological system (SES) framework links the variations of ecosystem services (ESs) and ecosystem functions with social policies. According to the results of the Erhai basin, there were increasing social demands and wanted provisioning ESs but degraded ecosystem functions over the last 70 years. Typically, the introduction of four major Chinese carps since the 1950s, the construction of hydropower stations on the Xi'er river since the 1970s, and the development of tourism since the 1990s, have been implemented to meet the social demands for wanted fish provisioning, hydroelectricity provisioning, and culture services respectively. Although there were temporary benefits in above desired services, improper strategies have gradually impaired the functions of native fish diversity, hydrodynamic forces, and nutrient cycling. Degraded ecosystem functions threatened the sustainable provision of wanted ESs, which motivated the implementation of subsequent social policies, such as the fishing ban after the 1950s, water level control after the 1970s and restoration projects after the 1990s. By rounds of renewed social drivers/policies, the social system and ecosystem in the Erhai basin are tightly connected in the form of a feedback loop in the SES, rendering dynamic changes in wanted ESs. The current social-ecological trap in the Erhai basin emphasizes the significance of SES framework and advantages of a paleolimnological approach in revealing the long-term SES dynamics, which can help tailor proper management measures in the future. [ABSTRACT FROM AUTHOR]