Ecological boundaries and their regional exceedance in China

Planetary boundaries have received considerable attention since they were first proposed, but applying various downscaling methods to the regional scale has certain limitations due to regional heterogeneity. The concept of ecological boundaries (EB) extends and complements planetary boundaries at a regional scale. However, previous studies have not considered the EB of multiple regions and the impact of interregional ecosystem service value (ESV) flows on EB. In this study, we optimized the EB accounting method and quantified the EB of 30 provinces in China from 2002 to 2017, then assessed the ecosystem unsustainability, and determined the impact of demand for goods and services on the consumption of local natural resources by each province in China using an ESV-extended multiregional input-output model. We found that EB increased in all provinces of China. The ecological unsustainability index of all 30 provinces was larger than 1, indicating a serious environmental unsustainability, but the magnitude of the index tends to decrease. Furthermore, the regions that have the greatest impact on exceeding EB in each province were concentrated in Guangdong and Henan. Guangdong had the highest total net imports in 2012 and 2015 (665.08 and 641.70 billion yuan, respectively), while Henan had the highest total net imports in 2017 (611.58 billion yuan). For the role of net exports, the rankings of the provinces differed in terms of the direct ESV and the boundary-exceeding ESV indicators. Our results reveal EB across provinces in China, underscoring the importance of considering the flow of ESV between regions in assessing the impact of exceeding EB. This study can assist policymakers in better allocating ecological resources within EB, which is critical for alleviating ecological pressures.