基于PSR的长江口生态系统的健康评价

ASSESSMENT OF ECOSYSTEM HEALTH OF THE YANGTZE RIVER ESTUARY BASED ON THE PRESSURE-STATE-RESPONSE MODEL

以长江口生态系统作为长江流域的终端影响受体,基于压力-状态-响应(press-state-response, PSR)概念模型,构建了长江口生态系统健康评价指标体系,确立了生态系统健康等级及标准,通过层次分析法确定了指标权重。采用建立的评价方法体系,对2001—2017年长江口生态系统健康进行评价,结果显示:长江口生态系统压力指数为0.08~0.47,总体呈波动下降的趋势,状态指数先上升后下降,数值分布于0.40~0.88,响应指数为0.45~0.94,呈波动上升的趋势。长江口生态系统健康评价指数为0.40~0.65,经历了先下降再上升的变化过程,多数年份生态系统健康等级为"中",2012,2013,2015年生态系统健康达等级达到"良",2006年健康等级为"差"。2001—2017年,长江口来沙量减少,长江口氮磷浓度高位振荡,浮游生物结构不稳定,赤潮频发是影响长江口生态系统健康评价指数的主要因素。

A health assessment method for the Yangtze River estuary ecosystem, which was considered as the terminal receptor of the Yangtze River basin, was established based on the conceptual framework of PSR(press-state-response). The main contents included: an ecosystem health assessment indicators system in which pressure, state and response parameters was taken into consideration;the weight of the indicators was determined by the analytic hierarchy process(AHP) method;the health of the Yangtze River estuary ecosystem was divided into five grades, “excellent” “good” “medium” “bad” and “poor”. The health status of the Yangtze River estuary ecosystem from 2001 to 2017 was evaluated by this method. The results of ecosystem health of the Yangtze River estuary during 2001—2017 showed that the pressure index values were between 0.08 and 0.47 and showed a trend of fluctuating downward, the state index showed a trend of falling after rising first with the values fluctuated between 0.40 and 0.88, the response index values fluctuated between 0.45 and 0.94 and showed a trend of fluctuating upward. The EEHI value was between 0.40 and 0.65 during the 17 years, 2001 to 2017. The EEHI dropped from 2001 to 2006, then rise slowly. According to the EEHI value, although the grade of the health of Yangtze River estuary ecosystem in 2012, 2013 and 2015 achieve “good” level, and the health of the Yangtze River estuary ecosystem was graded as “medium” level in most of the years. The main factors affecting the health assessment index of the Yangtze River estuary were the decrease of sediment inflow, the high shock of nitrogen and phosphorus concentration in the Yangtze River estuary, the instability of plankton structure and the frequent occurrence of red tides.