基于土地利用变化的区域生态安全评价--以鄂尔多斯市为例

Regional Ecological Security Assessment Based on Land-Use Change——A Case Study in Ordos City

在人类活动导致的生态环境问题中,土地利用变化对区域生态安全起着决定性的作用。选择地处我国北方农牧交错带的鄂尔多斯市作为案例区,以G IS和SPSS软件为平台,通过区域生态安全评价指标体系的构建、指标标准阈值的确定、区域生态安全评价模型的建立,对研究区1988、2000及2008年的区域生态安全状况进行了研究。结果表明:①研究区20 a来整体生态安全状况呈现"先恶化、后改善"的趋势,与2000年后"退耕还林还草"、"禁牧和休牧"政策的实施直接相关;②高覆盖度草地是最安全的土地利用方式,其次是中覆盖度草地,林地的生态安全水平非常稳定,水域和低覆盖度草地的生态安全多处于"临界安全"水平,相比之下,耕地、建设用地和未利用地最不安全;③各旗区生态安全水平差异较大,鄂托克旗"较为安全",鄂托克前旗和准格尔旗为"临界安全",达拉特旗和东胜区的生态安全值最低。研究结果可为当地生态环境管理提供更为有效的理论依据。

The cumulative effects of human activities on regional ecological security have attracted much attention in recent years.Land use/cover change plays a decisive role to regional ecological security.In this research,we chose Ordos which is located in northern agro-grazing eco-tone as the study area.Basing on GIS and SPSS software platform,we constructed indicators system of ecological security assessment,calculated the threshold and constructed model of ecological security assessment in 1988,2000 and 2008.From the studies above,the following conclusions can be drawn： 1）The ecological security situation of the study area got worse at first,but then improved in the year of 2000,which was directly related to the policies of returning farmland to forest（grass） and fencing and delaying grazing.This phenomenon indicates that economic activities such as land use and the enacting of policies affect regional ecological security level significantly.In addition,policies are playing a more and more important role in not only the development of agriculture and livestock,but also guiding the overall ecology.2） Grassland with high coverage rate got the highest level of ecological security among all land-use types,and grassland with middle coverage rate got the second.Ecological security of forestland was very steady.Water and low coverage grassland were often at a critical stage,and could be easily affected by precipitation,saline soil,as well as desertification.In contrast,farmland,built-up land and unutilized land were at the lowest ecological security level.3） Otog Banner was at the level of better security.Otog Front Banner and Jungar Banner were at the level of critical stage of security.Dalad Banner and Dongsheng District were at the lowest ecological security level.During the past 20 years,the ecological security has been getting better in Dongsheng District and Ejin Horo Banner,it first decreased and then increased in Otog Front,Otog,Hanggin,Uxin and Jungar banners to different degrees.The results could be beneficial for providing references to regional ecological management for the local government.