Changes Of Human Disturbance Intensity In Yunnan,Guangxi And Guizhou Provinces And Its Impact On Vegetation Restoration

Southwest Karst region is the concentrated distribution region of Karst landform in China.Fragile ecosystems,coupled with human disturbance intensity,having made serious rocky desertification and poverty problem in the region.In recent years,in the context of urbanization and ecological engineering construction and so on,the high intensity of human disturbance activities have been alleviated.Clarifying the specific functional characteristics of human disturbance intensity and their effects on vegetation restoration,which is helpful to evaluate the effectiveness of the first phase of the comprehensive control project of rocky desertification and to promote the smooth implementation of the second phase of the project.Based on the theories of geography,ecology and so on,taking 294counties(cities and districts)of Yunnan,Guangxi and Guizhou provinces as research units,the data of human disturbance and vegetation restoration at five time points in 1995,2000,2005,2010 and 2015 are used in this paper,quantifying and characterizing the human disturbance intensity with the methods of hierarchical difference maximization combined weighting,spatial auto correlation and so on.On this basis,the influence of human disturbance on vegetation restoration is analyzed by using geographical weighted regression model,in order to reveal the characteristics of vegetation restoration and human disturbance in Karst region,and to provide a decision reference for further comprehensive control of rocky desertification.The main conclusions are as follows:(1)In 1995-2015,the human disturbance intensity fluctuating decreased in Yunnan,Guangxi and Guizhou provinces,and the rate of decline was first fast and then slow.Before the implementation of the ecological project,the human disturbance intensity in the Yunnan,Guangxi and Guizhou provinces was large,and the human disturbance intensity decreased obviously after the implementation of the ecologicalproject,indicating that the implementation of the ecological project alleviated the high intensity of human activities.According to the level of disturbance intensity and its variation characteristics,the human disturbance intensity in the study area can be divided into five types:stable low type,changed lower type,changed middle type,changed higher type and changed high type.In different karst geomorphological regions,the distribution characteristics of human disturbance intensity are different,but the intensity of each type area is decreased.The human disturbance intensity in Yunnan,Guangxi and Guizhou provinces has significant spatial positive correlation,and the overall concentration degree is relatively stable,while the local auto correlation pattern is mainly in the unsignificant area,followed by high concentration and low concentration.The distribution of high agglomeration varies greatly and is relatively scattered.The distribution of low concentration is relatively stable,mainly concentrated in the southeast of Guangxi,and scattered in other regions.(2)In 1995-2015,the influence of human disturbance factors on vegetation restoration was quite different.In general,the land reclamation rate,multiple cropping index,the proportion of sloping land area and road density in the study area are mainly negative effects on vegetation restoration.The rural residential area,the number of tourists and the afforestation area of ecological engineering mainly played a positive role in vegetation restoration.Similarly,in 1995-2015,the dominant factors affecting the vegetation change in Yunnan,Guangxi and Guizhou provinces are obviously different,and the dominant factors among different karst landforms are quite different.Infrastructure construction and tourism are always the dominant factors affecting vegetation change,among which,tourism is always the dominant factor of vegetation change in middle and high mountain areas.The distribution range of positive and negative dominant effect remains stable all the time,and the negative dominant action is mainly concentrated in the area of peak-clusterdepression,most of karst fault basins,part of karst plateau and karst canyon,and part of non-karst area in the south of Yunnan province,the other regions play a positive role.