[Ecological security assessment of Tangshan City based on emergy analysis]

Based on 'pressure-state-response' model and by using emergy analysis method, the urban ecological security assessment system and urban ecological security index (EUESI) were constructed, and the variation of ecological security level of Tangshan City in 1995-2005 was evaluated. During this period, the ecological security level of the city increased first and decreased then. The EUESI increased from 0.017 in 1995 to 0.022 in 1996, then dropped yearly, and became unsecure in 2003. The urban ecological security assessment method based on emergy analysis overcame the disadvantages of conventional assessment system, e.g., numerous and repetitive indicators, non-uniform units, and poor comparability, and reflected the urban ecological security state more objectively, being able to provide scientific basis for urban ecological environment management and decision-making.