Evaluation and analysis of ecological security based on the improved three-dimensional ecological footprint in Shaanxi Province, China

The increase in human activities has led to a series of ecological issues such as ecological imbalance, environ-mental pollution and resource depletion. Developing a comprehensive, applicable and simple ecological security assessment system is critical for determining the current state of the regional ecological environment and formulating sustainable development strategies. Therefore, an integrated ecological security index was estab-lished in this study based on entropy method by incorporating the ecological pressure index (EPI), ecological utilization efficiency (EUE), ecological and economic coordination index (EECI) and utilization ratio of capital stocks to flows (Rstock flow ). The ecological security of Shaanxi Province from 2000 to 2019 was analyzed from single and comprehensive perspectives. The results showed that (1) during 2000-2019, the per capita ecological deficit of Shaanxi first increased at an average annual rate of 105.75 %, and then decreased at an average annual rate of 3.26 %, reaching a peak of-1.815 nha/cap in 2016. And the sequence of ecological deficit of three regions in Shaanxi was Guanzhong > Northern Shaanxi > Southern Shaanxi. Only Hanzhong, Shangluo and Ankang had an ecological surplus in 2019, whereas the remaining cities were in deficit. (2) Shaanxi's ecological footprint depth increased from 1.52 to 2.86 in 20 years, indicating that capital flow is insufficient to meet the ever-increasing consumer demand, and the capital stock has been continuously consumed. In 2019, the ecological footprint depth of the cities in Shaanxi ranked from high to low as Weinan (12.69) > Xianyang (9.98) > Tongchuan (7.39) = Yulin (7.39) > Xi'an (4.50) > Baoji (3.01) > Yan'an (2.08) > Hanzhong (1.34) > Shangluo (1.21) > Ankang (1.11). (3) Although Shaanxi's EUE continued to improve, the EPI, EECI and Rstock flow indicated that the ecological situation of Shaanxi was gradually deteriorating. (4) From 2000 to 2019, Shaanxi's IESI increased by 54.55 %, exhibiting the spatial distribution of Guanzhong > Northern Shaanxi > Southern Shaanxi. Only the IESI of Hanzhong, Ankang and Shangluo showed a downward trend, indicating that the level of ecological security was strengthening in these regions. The findings will help local governments develop and implement regional character-based policies in support of regional sustainable development. Moreover, this study provides a framework for evaluating ecological security with broad coverage, simple operation and comparable results.