Evaluating temporal-spatial variations of wetland ecosystem service value in China during 1990–2020 from the donor side based on cosmic exergy

Abstract

China has pledged to strictly maintain wetland ecosystem services at the COP 14 of the Ramsar Convention on Wetlands that was recently held in Wuhan, highlighting the necessity of measuring wetland ecosystem service value (ESV) in China. Yet existing studies mainly focus on ecosystem service valuation of wetlands from the consumer side, while a donor-side evaluation of the temporal-spatial characteristics of the wetland ESV of China is lacking. This study introduces the thermodynamic concept of cosmic exergy into the evaluation of wetland ESV, which provides an objective evaluation index for the unified measurement and analysis of the ecological value and degradation of resources in the process of material, energy, and information transformation of the ecosystem. By constructing a cosmic-exergy-based accounting framework for wetland ecosystem valuation, this study comprehensively investigated the temporal-spatial variations of China's wetland ESV during 1990–2020 from the donor side. Results showed that from 1990 to 2020, the total wetland ESV in China first decreased and then increased notably, with an overall growth rate of 22%. Meanwhile, the ecological quality of wetlands, as indicated by cosmic exergy intensity, showed an upward trend in the middle and lower reaches of the Yangtze River Basin, but a downward trend in western China. Regions in the Yangtze River Basin, the Qinghai-Tibet Plateau, and Northeast China were demonstrated as the major contributors to the total wetland ESV. In addition, this study identified the vital role of marsh wetlands in ecosystem service supply, contributing nearly 30% to the total ESV, and microclimate regulation was the most prominent service type, accounting for up to 74%. The outcome of this study can offer a new biophysical perspective for the donor-side valuation of wetland ecosystem services and may provide a benchmark reference for policymakers to formulate supporting measures for wetland production and restoration.