北方农牧交错带土地利用生态安全评价

土地利用生态安全评价是土地资源可持续利用研究的核心和基础。根据各评价指标对生态环境的影响程度,将其划分为很不安全(Ⅰ)、较不安全(Ⅱ)、临界安全(Ⅲ)、较为安全(Ⅳ)和很安全(Ⅴ)共5个等级。在GIS技术支持下,以北方农牧交错带192个县(旗、县级市)级行政单元作为基本研究对象,采用灰色综合评估方法评价各县土地利用生态安全,得出其综合权系数向量,并使用系统聚类方法将评价结果划归不同生态安全等级。结果表明:(1)1989年和2000年北方农牧交错带各县土地利用生态安全水平都较低,1989年以Ⅰ级为主,2000年以Ⅱ级为主。(2)与1989年相比,2000年各县土地利用生态安全水平普遍有所提高。(3)Ⅲ级区在1989年仅包括4个县,2000年扩大为24个县,并且以大兴安岭山地区和东北冲积平原地区、陕北黄土高原区分布最为集中。(4)1989年没有县达到Ⅳ级,而2000年仅有一个;12年来,没有任何一个县的土地利用生态安全达到Ⅴ级。

The Assessment on the Ecological Security of Land Use in the Farming-Pastoral Zone of Northern China

The assessment of land use is the core and base of the study on sustainable land use.All estimating indices are graded from very insecurity(Ⅰ),relative insecurity(Ⅱ),critical security(Ⅲ),relative security(Ⅳ) and very security(Ⅴ) by given quantitative criterions.Based on GIS technology,the ecological security of land use of 192 counties in the farming-pastoral zone of Northern China was evaluated by using Gray Comprehensive Assessment method.Then comprehensive weight coefficient matrix of objects was acquired.In general,the maximum component can be selected from the comprehensive weight coefficient matrix of objects to determine the evaluated result.The means to determine it follows maximal subjection grade principle.Conclusions indicated that:(1) as a whole,the ecological environment security of land use of every county was inferior in 1989 and 2000.Most counties belonged toⅠ-class regions in 1989,butⅠ-class counties were only five in 2000.the security of most counties was up to Ⅱ-class in 2000.(2) The ecological security of land use of most counties was more superior in 2000 than in 1989,which indicated the ecological environment quality was improved in 2000.(3) Only 4 counties belonged to Ⅲ-class region in 1989,however,they were added up to 24 in 2000 and mainly located in Daxingan mountain and alluvial plain area of northeastern China and Loess plateau of northern Shaanxi.(4) No county reached Ⅳ class in 1989,and only one in 2000.No any counties reached Ⅴ class in 1989 or in 2000.The ecological security problem of land use is still serious in a later period.