| The sensitivity of land desertification can be used as a basis for assessing the likelihood of desertification,and thus provide a strong scientific basis for desertification prevention and control work.This paper takes the Qinghai-Tibet Plateau as the research area,and combines the environmental sensitive area(ESA)evaluation method to construct a desertification sensitivity evaluation system from five aspects:terrain,soil,hydrology,climate,and vegetation.Using spatial distance model(SDM),the desertification sensitivity index(DSI)of the Qinghai-Tibet Plateau from 1990 to 2020 is calculated.Its spatiotemporal change characteristics are studied through a single dynamic degree,transfer matrix,superposition analysis,and center of gravity migration model,Using the Geographically Weighted Regression Model(GWR)to analyze the importance of each driving factor,based on the current situation of desertification sensitivity in the Qinghai-Tibet Plateau,the study area was divided into desertification control zones and prevention suggestions were proposed.The main results are as follows:(1)In the past 30 years,the non-sensitive area,slightly sensitive area,and moderately sensitive area of the Qinghai-Tibet Plateau have increased by 6.61×10~4 km~2,13.77×10~4 km~2,and 20.50×10~4 km~2,respectively.The severely sensitive area and the extremely severely sensitive area decreased by 14.96×10~4 km~2 and 29.00×10~4 km~2,respectively.The desertification sensitivity of the Qinghai Tibet Plateau has shown a fluctuating decreasing trend in the past 30 years,with the fastest improvement rate of desertification sensitivity during the period from 2000 to 2010.The direction of desertification sensitivity transfer is from high sensitivity to low sensitivity.(2)The spatial distribution of desertification sensitivity in the Tibetan Plateau presents a pattern of high in the northwest and low in the southeast.Insensitivity and mild sensitivity are mainly concentrated in the southeast of the Qinghai-Tibet Plateau,while severe sensitivity and extremely severe sensitivity are mainly concentrated in the northwest,and moderate sensitivity is located in the transition zone with a northeast southwest trend.In the past 30 years,except for the extremely sensitive gravity center moving northward,the rest of the gravity centers have moved northwestward.From the perspective of provincial administrative regions,the desertification sensitivity index in Yunnan has decreased most significantly,from 1.21 to 1.06.From the perspective of municipal(county)level administrative regions,except for the increase in the desertification sensitivity index in Huangnan Tibetan Autonomous Prefecture of Qinghai Province and Hotan Prefecture of Xinjiang,other cities(counties)have decreased,with the most significant decrease in the desertification sensitivity index in Nujiang Lisu Autonomous Prefecture of Yunnan Province,from 1.20 to 1.02.From 1990 to 2020,the changes of desertification sensitivity in the Qinghai-Tibet Plateau were mainly"slightly weakened"and"stable",with a small amount of"significantly weakened"and"slightly enhanced".The"significantly weakened type"was mainly distributed in the Nujiang Lisu Autonomous Prefecture of Yunnan Province and the Nyingchi Prefecture of Tibet.The"slightly weakened type"was mainly distributed in the Yushu Tibetan Autonomous Prefecture of Qinghai Province,Tianzhu County of Wuwei City,Gansu Province,Subei County of Jiuquan City,Gansu Province,Naqu Prefecture of Tibet,and Rikaze Prefecture.The"slightly enhanced type"was mainly distributed in the Huangnan Tibetan Autonomous Prefecture of Qinghai Province,Kashgar Prefecture of Xinjiang,and Changdu Prefecture of Tibet,the"significantly enhanced type"is mainly distributed in Kashgar and Hotan regions of Xinjiang.(3)In the past 30 years,the impact of natural driving factors is far higher than that of human driving factors,so natural factors play a leading role.Among the first level indicators,soil factors are the main factors affecting the sensitivity to desertification in the Qinghai-Tibet Plateau.Among the secondary indicators,vegetation coverage and soil erosion intensity are the main influencing factors for desertification sensitivity in the Qinghai-Tibet Plateau.(4)It is recommended to carry out targeted treatment in highly sensitive areas,focusing on combating desertification in the vicinity of residential areas and traffic arteries,mainly through combining chemical and biological measures.For land desertification in uninhabited areas within highly sensitive areas,it is necessary to follow natural laws,respect natural processes,and focus on protection.It is recommended to comprehensively control the moderately sensitive areas.The first step is to focus on controlling mobile and semi mobile sandy lands,mainly by combining biological and physical measures;The second step is to mainly take on-site protection measures for fixed and semi fixed sandy land;Finally,cultivate artificial grassland,and if necessary,prohibit grazing and recuperate.Forest land and grassland are widely distributed in low sensitive areas,and it is recommended to take protective measures,and if necessary,convert farmland to forests for forest land;Generally,grazing prohibition measures are not taken for grasslands,as the possibility of desertification in low sensitive areas is relatively small,and more reliance should be placed on their own ecosystem restoration functions. |
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