中亚跨境流域生态脆弱性评价及其时空特征分析——以阿姆河流域为例

生态脆弱性（EVI）的定量评估和长期分析,对于了解区域生态环境动态变化与指导生态环境保护与修复极为重要。但以往研究很少对跨境流域这一特殊单元进行生态脆弱性评价。以阿姆河流域为例,选择反映研究区植被、水文、气候、地形、土壤以及人类活动等方面的11个指标,通过共线性诊断分析,构建了阿姆河流域生态脆弱性评价体系,利用主观权重与客观权重相结合的方法确定指标权重,对1990-2015年研究区EVI进行了定量评价及时空特征分析。结果表明：（1）研究区生态环境呈恶化趋势,大部分区域处于重度脆弱状态,研究时段内重度脆弱性比例的平均值为46.40%;极度脆弱性占比在过去25年内呈增加趋势,从1990年的2.58%增加至2015年的16.97%,增幅为14.39%。（2）生态脆弱性在不同土地覆被类型之间差异巨大,其中草地的EVI值变化最大,裸地的生态环境最为脆弱,林地的生态脆弱性最小;研究区生态脆弱程度整体表现为裸地>灌丛>草地>耕地>城市用地>林地的规律。（3）EVI与地形因子的关系表明生态环境最为脆弱的区域主要位于低海拔地势平坦与高海拔坡度大的地区,而低脆弱性主要分布在海拔2500~3500 m或坡度15~25°的区间上。

Ecological vulnerability assessment for a transboundary basin in Central Asia and its spatiotemporal characteristics analysis: Taking Amu Darya River Basin as an example

Quantitative assessment and long-term analysis of ecological vulnerability (EVI) are greatly important for understanding the dynamics of regional ecological environment and guiding ecological environmental protection and restoration. However, in the previous studies, there was rare assessment for ecological vulnerability of the special area of a transboundary basin. In this paper, the Amu Darya River Basin was used as the study area and 11 indicators were selected to reflect the vegetation, hydrology, climate, topography, soil and human activities. After the collinearity diagnostics, an ecological vulnerability assessment system for the study area was constructed. Further, subjective weight method and objective weight method was combined to determine the weight of all indexes, and quantitative estimation for the ecological vulnerability and the spatiotemporal characteristics analysis of the study area from 1990 to 2015 were conducted. The results showed that: (1) The ecological environment of the study area showed a deteriorating trend, and most of the areas were in a heavy vulnerable situation; the average proportion of heavy vulnerability during the study period was 46.40%. The proportion of extreme vulnerability also increased from 2.58% in 1990 to 16.97% in 2015, an increase of 14.39% over the past 25 years. (2) The ecological vulnerability of the study area varied greatly among different land cover types. The EVI value of grassland changed the most, the ecological environment of bare land was the most vulnerable, and the ecological vulnerability of forest was the lowest. In all, the ecological vulnerability levels among different land cover types were in an oreder of bare land > shrub > grassland > cropland > urban land > forest. (3) The relationship between EVI and topographical factors indicated that the area with lower elevation and smaller slope or higher elevation and larger slope was the most vulnerable regions, while the area with low vulnerability was mainly distributed in the regions at an altitude of 2500-3500 m or on a slope of 15-25°.