Effects Of Human Activities On Landscape Pattern And Change Process Of Rocky Desertification In Pingguo County

Karst landform concentrated distribution area is mostly fragile ecological environment area.Under the continuous effect of high-intensity human activities,regional rocky desertification problem is more prominent.It is very useful for the rational distribution of population and socio-economic activities,for the evaluation of the effectiveness of comprehensive control of rocky desertification,and for providing scientific reference for future rocky desertification control.In this study,Pingguo County,a widely developed karst area,was selected as the research area.Based on the interpretation of six remote sensing images in 1990,1995,2000,2005,2010 and 2015,the temporal and spatial dimension change characteristics of rocky desertification landscape were analyzed by using quantitative analysis methods such as dynamic degree and landscape index.Based on land use data,population density,GDP density and other data,the comprehensive intensity of human activities is simulated and calculated,and the temporal and spatial variation characteristics and agglomeration characteristics of the comprehensive intensity of human activities are analyzed.At the level of landscape and type,landscape index was selected to analyze the impact of comprehensive intensity of human activities on landscape diversity,connectivity and fragmentation.The main conclusions are as follows:(1)Compared with 1990,the area of rocky desertification in Pingguo County decreased in 2015,and the rocky desertification rate decreased by about 16 percentage points.From 1990 to 2015,the area of light rocky desertification fluctuated little,the area of moderate rocky desertification fluctuated greatly,and the area of severe and very severe rocky desertification decreased gradually in the later stage.The difference of single dynamic degree of different types of rocky desertification is obvious.The single dynamic degree of moderate rocky desertification is the largest,and that of light rocky desertification is the smallest.The comprehensive dynamic degree shows a trend of increase decrease increase.Different types of rocky desertification landscape spatial distribution difference is significant,each type of patch in the landscape evenly distributed,landscape connectivity is good,fragmentation showed a trend of first increase and then decrease.(2)Taking 2000 as the boundary,the comprehensive intensity of human activities in Pingguo County from 1990 to 2015 first increased and then decreased in the early stage,and continued to increase in the later stage.During this period,the number of medium intensity villages decreased,while the number of high and high intensity villages increased.The southwest of Pingguo County showed a trend of high intensity type expansion,the southeast showed a trend of medium intensity type reduction,and the middle showed a trend of low intensity type reduction.The spatial distribution of different intensity types in Northwest and northeast was relatively stable.The overall autocorrelation of the comprehensive intensity of human activities is gradually increasing,and the overall spatial distribution of different agglomeration types is relatively stable at the same time point.The high and high agglomeration types have the strongest agglomeration,mainly distributed in Matou Town,while the low and low agglomeration types are scattered,mainly distributed around and in the central hinterland.(3)The comprehensive intensity of human activities had the most significant impact on the diversity of rocky desertification landscape in Pingguo County,followed by fragmentation and connectivity.From the landscape level,the connectivity of rocky desertification landscape increases with the increase of the comprehensive intensity of human activities,while the diversity and fragmentation decrease with the increase of the comprehensive intensity of human activities.From the type level,the landscape diversity,connectivity and fragmentation of severe rocky desertification are greatly affected by the comprehensive intensity of human activities,while the landscape diversity,fragmentation and connectivity of severe rocky desertification decrease with the increase of the comprehensive intensity of human activities.The results show that the comprehensive intensity of human activities has a significant impact on the rocky desertification landscape.