Abstract: Aiming at the potential catastrophic characteristics of coastal city under rapid urbanization, and based on the P-S-R (pressure-state-response) framework and catastrophe progression method (CPM), this paper developed a catastrophe model for the assessment of urban ecosecurity, and assessed the ecological security status (ESS) of Xiamen City from 1996 to 2006. The results showed that from 1996 to 1998, the ESS had an improving trend, revealing that the rapid urbanization in this period had less effect on the regional ecosecurity. From 1998 to 2001, owing to the largescale and profound ecological disturbances from sea reclamation and rapid population increase that far overstepped the ecological remediation ability of Xiamen City’s ecosystem itself, the ESS declined rapidly. From 2001 to 2006, the ESS improved again, because of the significant strategic transformation of Xiamen City from its original island-based configuration to a new eco-city with larger bay area. In 2006, the security of Xiamen ecosystem pressure remained at grade Ⅲ, suggesting that this city still had a potential risk of ecological security. According to our research results, CPM revealed the catastrophic effects of large development projects on ecosystems when a single index was at extreme, and offset the drawbacks of existing methods in this regard. CPM also had less subjectivity in weight evaluation and less uncertainty in estimating the standard of security, and consequently, could evaluate the status and development trend of urban eco-security exactly.

Key words: lowly efficient Tamarix chinensis shrub, growth index, soil physical and chemical indices, classification, Yellow River Delta.