Assessment of physical quantity and value of natural capital in China since the 21st century based on a modified ecological footprint model.

Natural capital accounting is an essential prerequisite for the harmonious development of human beings and nature and benign interactions between economy and environment. Although the ecological footprint has significantly contributed to sustainability evaluation for many years, the traditional ecological footprint model is limited by lack of value accounting, incomplete account content, neglect of multi-functions of land, and geographical spatial heterogeneity. These limitations reduce the universality of this model. To improve the value accounting of the ecological footprint model, this study takes national hectares (nha) as the measurement unit and includes the freshwater and pollution footprints. The dynamic changes of natural capital from 2000 to 2018 were calculated and analyzed in 31 Chinese provinces. The main findings are summarized here. China's physical quantity of ecological footprint, ecological carrying capacity, and ecological deficit in 2018 was 4.03, 0.79, and -3.24 billion nha, respectively. The energy account contributed most of the physical quantity in the ecological footprint (72.12% of the total). From 2000 to 2018, the physical quantities of the per capita ecological footprint and the per capita ecological deficit increased at 5.49% and 10.08% per annum, respectively, while the physical quantity of the per capita ecological carrying capacity decreased by 0.55% per annum. The physical quantities of the per capita ecological footprint and per capita ecological deficit were spatially distributed, reducing in the order of East > Central > West. The spatial distribution of the physical quantity of the per capita ecological carrying capacity showed the opposite trend. By 2018, China's ecological footprint, ecological carrying capacity, and ecological deficit were valued at 18.09, 12.44 and CNY -5.65 trillion, respectively. Over the 2000-2018 period, the per capita ecological footprint and ecological carrying capacity increased by 495 and CNY 370 per annum, respectively, while the per capita ecological deficit expanded at CNY -125 per annum. The biological account contributed approximately 59.53% of the value quantity of the ecological footprint. Since the twenty-first century, the cumulative effect of excessive consumption has placed increasing pressure on China's ecosystems. On mainland China, only Tibet showed an ecological surplus in 2018. The ecological pressure index decreased in the order of East > Central > West. As Western China has developed extensively and its ecological deficit is rapidly expanding, this region deserves special attention. The most ecologically challenging regions in China are Shanghai, Tianjin, and Beijing. In contrast, Jilin, Qinghai, and Tibet impose low ecological pressure in China. These findings contribute to the standardization and localization of the ecological footprint model in China and provide a reference for regional resource management and ecological construction.