西安市生态安全的时空变化预测

Spatial and temporal analysis of ecological security of Xi'an City

本文改进了生态足迹方法，提出了生态压力指数的概念，并在此基础上建立了生态安全评价指标体系。利用该指标体系对1991—2003年西安市的生态安全进行了评价。结果表明：1991年西安市的生态安全分为3类，即生态安全区域，生态压力指数为Ⅰ级，包括周至县和蓝田县；生态预警区域，生态压力指数为Ⅱ级，包括户县、长安、临潼和高陵县；生态不安全区域，生态压力指数为Ⅲ级，包括西安市区和阎良区。1991后西安市各县区的生态环境演进态势可分为3种情况：一是生态压力指数下降，生态好转的区域，如周至、蓝田、户县、高陵县；二是生态压力指数上升，生态恶化的区域，如长安和临潼；三是生态压力指数稳定，生态基本没有变化的区域，如西安市区、阉良区。到2003年，周至县、蓝田县依旧属于生态安全区；户县和高陵县由生态预警区变为生态安全区，长安区和临潼区却由生态预警区变为生态不安全区；西安市区和阎良区依旧为生态不安全区。因此，2003年西安市的生态安全分为2种类型，生态安全区和生态不安全区，生态预警区消失。

Based on ecological footprint method, an ecological tension index was put forward and ecological security assessment index established on the ecological security of Xi＇an City from 1991 to 2003. The results show that the ecological state of Xi＇an City in 1991 can be stratified into three： Ecological safety region, including Zhouzhi and Lantian Counties, with grade Ⅰ ecological tension index; ecological warning region, including Huxian, Chang＇an, Lintong and Gaoling Counties, with grade Ⅱ ecological tension index; and ecological insecurity region, including Xi＇an Cantonal and Yanliang County, with grade Ⅲ ecological tension index. After 1991, ecological security change shows three types of trend： Declining ecological tension index type, including Zhouzhi, Lantian, Gaoling and Huxian counties, with improving ecological environment; rising ecological tension index type, including Lintong and Chang＇an Counties, with deteriorating ecological environment; and static ecological tension index type, including Xi＇an Cantonal and Yanliang County. Onto 2003, the ecological state of Xi＇an City can be divided into two strata： ecological safety region and ecological insecurity region. Zhouzhi and Lantian Counties still belong to ecological security region; Huxian and Gaoling Counties have moved up from ecological warning region to ecological security region; yet Chang＇an and Lintong Counties have dropped down from ecological warning region to ecological insecurity region; while Xi＇ an Cantonal and Yanliang County still remain in ecological insecurity region.