Urban ecological security assessment for cities in the Beijing–Tianjin–Hebei metropolitan region based on fuzzy and entropy methods

Based on the pressure–state–response conceptual model, we constructed the urban ecological security evaluation index system for 13 cities in the Beijing–Tianjin–Hebei metropolitan region from 2003 to 2014, where integrated development has occurred up to the national strategic level. The entropy-weight method was used to calculate the index weights to eliminate subjectivity. After the perfection and detailing of the increased half-ladder membership function and the confirmation of the membership standard of urban ecological security evaluation, the fuzzy synthetic evaluation method was used to calculate, analyze and evaluate the ranks of urban ecological security from 2003 to 2012. The overall regional ecological security of the Beijing–Tianjin–Hebei metropolitan region increased during those 10 years. However, as expected for the obvious increase in the ecological state security level, neither the ecological pressure security nor the response security level significantly changed. In addition, urban social and economic indicators contributed more to the ecological security assessment than did the natural resource indicators and environmental indicators.