干旱—半干旱典型生态脆弱区生态脆弱性时空演变及驱动因子分析

Spatial-temporal variations and driving forces of the ecological vulnerability in the typical arid/semi-arid ecologically vulnerable areas

干旱—半干旱区是我国生态系统最脆弱的地区之一,科学评价生态脆弱性有助于掌握其生态系统状况及驱动机制。然而以往研究多以地理或行政区划界线作为研究区划分依据,不能有效反映典型气候区内生态脆弱性演变规律及其机制。综合考虑干旱—半干旱区主要生态问题,基于“暴露—敏感性—适应力”评估模型框架,从气候、水土流失、人为干扰和生态系统服务等层面选取了13个评价因子,结合主成分分析法和层次分析法进行生态脆弱性评价,同时利用地理探测器和逐步线性回归法分析了2000—2015年干旱—半干旱典型生态脆弱区生态脆弱性时空变化及其驱动因子。结果表明:1)干旱—半干旱典型生态脆弱区的脆弱性水平整体较高,中度及以上面积占比超3/4,并呈自东向西先增后减的趋势,且不同土地利用类型的脆弱性水平差异较大;2)研究时段内,生态脆弱性先增后降,整体呈显著下降态势,脆弱度指数由0.92先增加到0.97,再降低到0.87;3)生态脆弱性的空间分布主要受气温、水分及地形起伏状况的影响(q均值>0.76),年际变化主要受植被覆盖和年降水量的影响,解释率最高分别可达45%和17%。强调基于气候分区及其相关生态问题的生态脆弱性评价框架的有效性,研究结果可为我国干旱—半干旱区的生态环境保护提供决策支持。

The arid/semi-arid is one of the most eco-fragile regions in China,and therefore a scientific assessment on the ecological vulnerability can enhance our knowledge on its ecological conditions and driving mechanisms.However,previous studies mostly defined their research areas according to geographical or administrative boundaries,which cannot effectively reflect the variability and drivers of the climate-zone specific ecological vulnerability.Basing on the framework of the“exposure-sensitivity-adaptability”,this study screened 13 factors in multiple terms such as climate,soil erosion,anthropogenic disturbance,and ecosystem services by considering the major ecological issues under arid/semi-arid climate,and evaluated the spatial-temporal variations of the ecological vulnerability in the typical arid/semi-arid ecologically vulnerable areas during 2000—2015 by a combination uses of principal component analysis(PCA)and analytic hierarchy process(AHP)method.The drivers were then explored by Geodetector and stepwise linear regression methods.The results showed that(1)the ecological vulnerability of the typical arid/semi-arid ecologically vulnerable areas were overall high,and the proportion of the area of moderate or above was more than 3/4,with an increasing and then a decreasing trend from the east to the west,and the vulnerability differed greatly by land use type.(2)The ecological vulnerability decreased after an increase,and overall decreased significantly in the study period,with the ecological vulnerability index(EVI)first increasing from 0.92 to 0.97 and then decreasing to 0.87.(3)The spatial variations of the ecological vulnerability are mainly contributed by temperature,moisture,and topography(q mean>0.76),while the inter-annual trends are mainly caused by the changes of vegetation coverage and precipitation,with the highest explanatory rates reaching 45%and 17%respectively.This paper emphasizes the effectiveness of the ecological vulnerability assessment according to the framework considering the climate zones and their ecological problems,and the results can provide insights for policymaking of environmental protection in the arid/semi-arid regions of China.