叶尔羌河流域土地生态脆弱性差异评价

综合评估叶尔羌河流域土地生态脆弱性，为流域重点治理、恢复绿洲生机提供决策依据和理论支持。以叶尔羌河流域作为研究区，获取2008—2018年各时期不同指标层数据，利用ArcGIS 10.5的栅格计算功能与自然间断分类法，综合计算研究区生态脆弱性指数，并将其划分为5种脆弱等级并表征其时空分布。结果表明：在空间分布上，研究区以微度、轻度脆弱区为主，面积占比分别为35.67%、33.63%，主要分布在叶尔羌河中下游冲积扇平原；中、重度脆弱区比重次之，分别占比为14.89%、12.93%，主要分布在叶尔羌河上游山地丘陵区；极度脆弱区面积占比最小，仅为2.89%，但面积亦有3 000 km²，主要分布在叶尔羌河中下游人口密集区，对流域整体生态环境起着“木桶效应”。局部地区生态环境持续恶化，致使流域整体生态压力与生态“阈值”的平衡受到影响。在时间分布上，2008—2011年整体评价指数下降0.04324，2010—2014年整体评价指数下降0.005 41，2014—2018年整体评价指数下降0.056 86。虽然各时期土地生态脆弱指数不同程度降低，流域整体生态环境呈改善趋势，但中、重、极度脆弱区依旧分布广泛，亟需研究其分布规律，针对不同脆弱区提出具体调控对策。

Evaluation on the difference of land ecologicalvulnerabilityin the Yarkant River Basin

A comprehensive evaluation of the characteristics ofland ecological fragility in the Yarkant River Basin,Xinjiang,China provides adecision making basis and theoretical support for river basin key managementand the restoration of oasis vitality.In this study,the Yarkant River Basin isthe research area.By obtaining the relevant data of different index layers ineach period from 2008 to 2018,we usedthe grid computing function of ArcGIS 10.5 and the natural discontinuous classification method tocomprehensively calculate the ecological vulnerability index of the studyarea.We divided the vulnerability into five levels and presented itsspatiotemporal distribution.Results show that in the spatial distribution,thestudy area is dominated by micro and lightly vulnerable areas,with an arearatio of 35.67% and 33.63%,respectively,distributed in the alluvial fan plainin the middle and lower reaches of the Yarkant River.The proportion ofmoderately and severely vulnerable areas was secondary,accounting for 14.89% and 12.93%,respectively,distributedin the hilly areas of the upper reaches of the Yarkant River.Although theproportion of extremely vulnerable areas is only 2.89%,which is 3 000 km²,distributedin densely populated areas in the middle and lower reaches of the YarkantRiver,it plays a role of the cask effect on the overall ecological environmentof the basin.The local ecological environment continues todeteriorate,resulting in a balance between the overall ecological pressure ofthe basin and the ecological threshold.Regarding the time distribution,theoverall evaluation index decreased by 0.043 24 from 2008 to 2011,and theoverall evaluation index decreased by 0.005 41 from 2001 to 2014.The overall evaluation index decreased by 0.05686 from 2014 to 2018.Although the ecological vulnerability index of each perioddecreased to varying degrees,the overall ecological environment of the basinimproved.However,the moderately,heavily,and extremely vulnerable areas arestill widely distributed.Based on the representative SRP model and fieldsurvey,this study proposed some methods.In the micro and lightly vulnerableareas,basic pollution control is needed.In moderately and severely vulnerableareas,ecotourism should be developed,and food crops should be converted toexport-oriented forestry and fruit growing.The sustainable development oforchards,farmhouses,and other rural plain ecotourism resources should bepromoted.In extremely vulnerable areas,strict control of space use andecological immigration should be implemented.