| The 21st century,the karst landform landscape of the southwest karst area there are certain ecological problems,under the artificial intervention of a long period of time,the ecological environment become very sensitive,accelerates the rocky desertification development,the human-land contradiction between population-resources-environment has a direct impact on ecology,society and economy,and also hinders sustainable development.The state and local governments organically integrate ecological restoration,small-scale water conservancy and soil conservation projects,and environmental governance with the control of rocky desertification,and implement comprehensive control of rocky desertification.After more than ten years of treatment,rocky desertification has been effectively controlled,the ecological environment has gradually improved,and the vegetation coverage has increased significantly,which has promoted the sustainable development of social and economic construction.Rocky desertification sensitivity reflects the degree to which rocky desertification is likely to occur,is a compass to find areas where rocky desertification may occur,and is also the prerequisite and basis for comprehensive control of rocky desertification and related ecological restoration.At present,there are few researches on the sensitivity evaluation of rocky desertification in karst areas and the impact evaluation of combined human intervention,and most of them are one-phase data,and the law of rocky desertification sensitivity and artificial intervention intensity is not significant.In order to accelerate the speed of improving rocky desertification in karst areas and enhance the stability of the ecological environment,the typical karst areas are selected as the research object to conduct research on rocky desertification-related content.Taking Xixiu District of Anshun City as a typical karst area,the study reveals the spatial evolution of rocky desertification in the study area at different times.At the same time,it deeply explores the relationship between the distribution characteristics of rocky desertification in karst areas in various periods and its natural and human key driving factors.Based on the natural environment and humanistic characteristics of Xixiu District,RS and GIS are used for technical processing,combined with remote sensing image data,historical basic geographic data and socio-economic survey statistical data,to construct a rocky desertification sensitivity evaluation and artificial intervention intensity evaluation model.The comprehensive method of"AHP+entropy weight method"calculates the weight of each index,and obtains the sensitivity evaluation of rocky desertification and the evaluation of human intervention intensity with the characteristics of Xixiu District.Analyze the temporal and spatial general trend of rocky desertification sensitivity in this area and the coupling relationship with rocky desertification,analyze the changes in the intensity of human intervention under rocky desertification sensitivity,and provide effective guidance for the comprehensive control of rocky desertification in the future,and also provides a basis for selecting ecological restoration areas in karst areas.The main research results are as follows:(1)During the period from 2008 to 2018,the degree of rocky desertification in Xixiu District gradually decreased,and the ecological environment gradually improved.Excluding non-karst landforms and areas without rocky desertification,mild and moderate rocky desertification are the main ones.In 2008,2013,and 2018,the area of rocky desertification was 583.46km~2,557.74km~2and 256.39km~2,accounting for 37.03%,35.39%and 16.17%of the total area respectively.According to statistics on the area of rocky desertification in all townships in Xixiu District,it was found that the degree of rocky desertification was the most serious in Yanla Township,Yaopu Town and Yangwu Township in 2008 and 2013.After 2018,severe rocky desertification will be transferred to Longgong Town,Xinchang Township and Songqi Town.The proportions of rocky desertification are22.36%,39.25%and 24.83%respectively.Generally speaking,the degree of rocky desertification in the study area has improved faster than its deterioration.At the same time,the analysis of the current distribution of rocky desertification in various periods in the area and the key natural and man-made driving factors found that,among the natural driving factors in Xixiu District,rocky desertification is mainly distributed in areas with medium slopes ranging from 8~o-25~o,vegetation coverage of 60%,and bedrock exposure rate of more than 50%.Among the man-made driving factors,rocky desertification Desertification is mainly distributed in dry land,bare land,and shrubs.The population density is greater than 500people/km~2and less than 200 people/km~2.The per capita GDP is in the middle and low-level areas,and the road density is between1.50-2.15km/km~2.With the promotion of the comprehensive control project of rocky desertification and the expansion of the control scope,the serious degree of rocky desertification gradually shifts to the degree of non-rocky desertification and potential rocky desertification.(2)The sensitivity of rocky desertification is evaluated by selecting five evaluation indicators of whether it is carbonate rock,slope,vegetation coverage,exposed rate of foundation stone,and land use.It is found that the sensitivity of rocky desertification in the study area is mainly mild to moderate,and there is no extremely sensitive area,indicating that the ecological environment is relatively stable and tends to be higher in the west and lower in the east.From 2008 to 2018,the area of the highly sensitive area was reduced from 794.79km~2to 639.4km~2.According to the spatial analysis,the rocky desertification sensitivity of the study area is in a benign development,with monomorphic improvement as the main form.Combining with the distribution of rocky desertification,it can be seen that rocky desertification is in a light to moderately sensitive area,and the area of the medium to high sensitive area gradually decreases with the passage of time after the control of rocky desertification.(3)Through the evaluation of the intensity of human intervention,it can be seen that light intervention is the main focus of comprehensive control of rocky desertification in the early,mid and late stages,accounting for 79.72%of the total area.The scope of human intervention is gradually expanding in terms of spatial distribution,diverging from the urban area as the center.Combined with the sensitivity to rocky desertification,it is found that all levels of sensitivity are mainly light intervention,and mild and moderate are supplemented.With the increase of the range of human intervention,the area of rocky desertification sensitive area decreases gradually.In the comprehensive control of rocky desertification,preventive measures shall be taken in the rocky desertification insensitive areas,and restoration measures shall be taken in the rocky desertification sensitive areas.The area size of the control types is in order as follows:artificial afforestation and planting grass>other infrastructure construction projects>closing hills for afforestation>slope conversion to terraces,effectively controlling the risk of aggravated rocky desertification. |
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