民勤县生态承载力动态趋势与驱动力分析

Dynamic trend of ecological carrying capacity and driving force in Minqin,China

在全球变暖的大气候背景下,自然与人文因素的双重驱动下,民勤县的生态环境急剧恶化,民勤县生态承载力动态趋势的定量评价和驱动力分析对于促进该地区生态环境保护和可持续发展具有重要意义。文中利用基于生态足迹方法的生态承载力时间动态趋势评价方法,建立了民勤县1990-2007年18年间生态承载力供给与需求的时间动态趋势模型,对其趋势的变化速率与剪刀差进行了定量评价,预测了各项指标2008-2017年10年间的发展趋势,并分析了导致该趋势变化的自然与人文因素驱动力。研究结果表明:民勤县过去18年间人均生态承载力供给和需求呈差异不断增大的反向发展趋势,其中人均生态承载力需求加速增长,而人均生态承载力供给加速降低,供求趋势的剪刀差呈持续增大趋势,年均增长率达7.12%;其间,全县可载人口数持续降低,至2007年,民勤县可载人口数降至16.5万人,超载人口数增至14.7万人;未来10年内民勤县的生态承载力供求矛盾将呈不断加剧的态势,不可持续发展的状况将日趋严重。导致民勤县生态承载力供求矛盾不断加剧的主要驱动力包括水资源日益匮乏、土地生产力不断降低、人口压力持续增大,人口消费量急剧增长,消费结构和土地利用方式的不合理等等。

The dynamic trends and driving factor analysis of Ecological Carrying Capacity （ECC） are the hot question in the field of ecolgocal security and sustainable development research. Using the temporal dynamic estimation methodology of regional Ecological Carrying Capacity （ECC） which quantificationally describe the development trends of EF and ECC and their differences to reflect the state of ecological sustainability in a long time series based on Ecological Footprint （EF） methodology,we calculated the EF and ECC change rate per capita, scissors difference and some relating indices of Minqin county during 1990 - 2007 and forecasted them during 2008 - 2017. As the results shown,from 1990 to 1994,the EF per capita was greater than the ECC per capita, which indicated that the ecological state of Minqin county was the ecological surplus; from 1995 to 2017,the EF per capita was less than the ECC per capita,indicating that Minqin has been in the ecological deficit; from 1990 to 2017,the EF per capita will increase with the increase of the change rate; the ECC per capita decrease with the descending change rate; the scissors difference between the both of trends increased by 7. 12% per year. The ecological carrying-pressing index also increase rapidly during the period,and the overshooting population index started in 1995 and increased from 1995 to 2007. All results showed Minqin has been in the state of unsustainable development and its unsustainability has been increasing after 1995. There are main natural driving forces and man-made driving forces accelerating the dynamic of ECC in Minqin,including lack of water resource,irrational water and land use,declining ecological productivity,increasing population and its natural capital consumption.