The Evolving Interrelationships Between Desertification And Rural Residential Areas

At present,the harm of rocky desertification and its control has become one of the hotspots and difficulties in the ecological research of karst areas in China.Only by deeply exploring the evolution characteristics and formation mechanism of rocky desertification can we better guide the ecological restoration of rocky desertification areas.As one of the important factors of rocky desertification,human activities can reveal the driving mechanism of man-made factors by analyzing the relationship between its changing characteristics and rocky desertification.to guide the optimization of the layout of rural settlements in rocky desertification areas and the formulation of a work plan for the control of rocky desertification.In this study,Pingguo County in Guangxi is selected as the study area,as one of the areas with the largest karst area,the most typical karst geomorphology and the widest and most serious rocky desertification area in Guangxi and the whole country.Pingguo County is also a gathering area of poor population and ethnic minorities,as well as a demonstration area for ecological control of rocky desertification.The contradiction among local population,economy and ecology is prominent,which has important representative significance in karst research in southwest China.This study summarized and described the change characteristics of rural residential land scale,patch number,density,shape,coefficient of variation,scale,evolution type,coefficient of variation and severity of rocky desertification in Pingguo County from 1989 to 2017.to find out the law of their spatiotemporal evolution.On this basis,a geographic detector model is constructed to analyze the correlation between the evolution type,coefficient of variation,comprehensive score of rocky desertification and rural residential land scale,patch number,coefficient of variation,landscape shape index and evolution rate.the internal driving mechanism and interaction are found out,and the conclusions are as follows:(1)Affected by traffic trunk lines and rivers,the spatial distribution of rural residential land in Pingguo County is uneven,showing the characteristics of more in Northeast and Southwest and less in Central;and the density is dense in the north and south and sparse in the middle,gathering to both sides of towns,rivers and traffic trunks.and the trend of agglomeration is becoming more and more obvious,the change of lowdensity area is slow,and the density of high-density area increases continuously,from "single-point high value" to "multi-point high value";The landscape shape index is high in the south and low in the north,and decreases from southwest to northwest.During 1989-2017,the landscape index increases continuously,the patch irregularity increases,and the evolution rate shows a slow-fast-slow-fast trend.(2)The order of the scale of rocky desertification in Pingguo county is as follows: intensity > potential > moderate > extreme intensity > mild.Rocky desertification in densely populated areas such as northeast and southwest of the county is more serious.During 1989-2017,the area of rocky desertification in Pingguo county showed a fluctuating trend of increase-decrease-increase-decrease.The area without rocky desertification increased,moderate and intense rocky desertification was relatively stable,and mild and extreme intensity rocky desertification significantly decreased under the control project.The evolution mostly occurs at the junction of rocky desertification of different intensity.The overall fluctuation of rocky desertification area is relatively small,roughly showing the law of fluctuation decreasing in southwest and central part,and increasing in southeast and north;the succession type of rocky desertification is mainly stable,the forward succession and reverse succession are basically the same,and the interannual succession rate is uneven.(3)The evolution rate,coefficient of variation and landscape shape index of rural settlements have strong explanatory power and coordination to the evolution of rocky desertification,which play an important role in the evolution of rocky desertification.The influence of the interaction of any two driving factors of rural residential land on the spatial difference of rocky desertification is greater than that of single driving factor,and the type of interaction is two-factor enhancement or non-linear enhancement.The evolution rate,coefficient of variation and landscape shape index of rural settlements have a strong synergistic effect on other indicators.All the indexes that play an important role in explaining the evolution of rocky desertification have good significance test results,which further confirms that the evolution rate,coefficient of variation and landscape shape index of rural settlements are the leading factors of rocky desertification evolution.it also plays an important role in explaining the changes of each index of rocky desertification.(4)Rational planning and layout of rural residential areas can reduce the unreasonable human activities caused by the construction of rural residential areas and effectively slow down the deterioration process of rocky desertification,and rocky desertification control should be carried out according to its intensity characteristics.according to local conditions to arrange ecological relocation,small watershed management,ecological three-dimensional agriculture,eco-tourism,mountain closure for forest,vegetation management and other management measures;Improving public services and infrastructure construction,guiding the distribution of population and rural settlements,and improving the livelihood of farmers have important auxiliary significance for alleviating the contradiction between people and land in rocky desertification areas.