Exploring the formulation of ecological management policies by quantifying interregional primary ecosystem service flows in Yangtze River Delta region, China.

Ecosystem services (ESs) play an important supporting role in the development of human society and the economy. Despite the increasing number of ESs quantitative evaluation studies that have been conducted at different scales, the assessment of ESs flows between different administrative regions, which provides valuable implications for ecological protection and compensation, has drawn little attention. The aim of this study is to fill in this gap by providing a comprehensive ES interregional flow analysis method that evaluates ecosystem service values (ESVs) and quantifies the interregional flows in the Yangtze River Delta (YRD), which is home to one of the largest urban agglomerations in China. The results showed that the total ESV of the YRD increased from 2.02E+12 Chinese Yuan (CNY) in 2000 to 2.33E+12 CNY in 2019, a 15.23% increase rate. All types of ESVs displayed an increasing trend during the 20 years. According to the analysis of interregional ES flows in the YRD, Zhejiang province played a crucial role as a service providing area (SPA) for the spatial value transfer at the provincial level in both 2000 and 2019. Anhui province was the largest service benefitting area (SBA) of water conservation and CSOP, while Jiangsu province was the largest SBA of soil retention. The recognition of interregional ESV flows can provide valuable information for environmental planning and management to help improve China's ecological compensation policies for different administrative divisions.