Reconciling ecological footprint and ecosystem services in natural capital accounting: Applying a novel framework to the Silk Road Economic Belt in China

Natural capital is a constraint on sustainable development goals. There are multiple methods available for natural capital accounting, many of which are inconsistent with each other in accounting items. Another common defect is an inability to represent both physical and monetary quantities. To address these issues, we integrated the ecological footprint and ecosystem service methods by introducing ecosystem service equivalence factors that facilitate the formulation of a standardized and flexible natural capital accounting framework. Adopting the provinces along the Silk Road Economic Belt (SREB) in China as the target research area, this study calculated and analyzed the spatiotemporal evolution of natural capital utilization and ecological pressure from 2000 to 2020. The results revealed that the supply of natural capital in China's SREB cannot meet consumer demands, resulting in the expansion of the ecological deficits. From 2000 to 2020, the physical and monetary quantities of ecological footprint per capita in the SREB increased by 2.51 and 3.66 times and the ecological carrying capacity per capita decreased by 6.81% in physical terms, gradually increasing by 59.93% in monetary terms. The physical and monetary quantities of ecological deficit per capita continued expanding negatively, at rates of -0.133 nha/cap/yr and -299.837 CNY/cap/yr, respectively. Integrating the physical and monetary dimensions, the sustainability of natural capital in China's SREB was weakening, and the ecological pressure was increasing step by step, from the low-relatively low (L-RL) class to the relatively high-relatively high (RH-RH) class. Ningxia, Chongqing, Shaanxi, Guangxi and Xinjiang were the provinces facing the greatest ecological challenges along the SREB in China, while Qinghai faced the least ecological pressure. These findings provide a reference for the scientific utilization and management of natural capital in provinces along the SREB in China. Additionally, the proposed framework enriches the interactive research achievements of ecological footprint and ecosystem service theories, in ways that not only compensate for the lack of monetary quantity in the ecological footprint, but also have the potential to serve the compilation of China's government-mandated Natural Resource Balance Sheet.