| Rural residential area is the main place where rural residents engage in production and live,and its spatial evolution is influenced by location,nature,economic and social factors.Rural residential area in ecologically vulnerable areas of Karst have their regional characteristics.Starting from the scale of natural village in research,it is of great significance for promoting intensive and economical use of rural land in ecologically vulnerable areas to analyze the spatial variation characteristics of rural residential land in karst areas and explore the relationship between influencing factors and spatial evolution of rural residential land and identify the dominant factors that affect its spatial variation.This paper takes Pingguo County in Guangxi Province as the research area,and takes natural villages as research units by dividing the natural villages,and analyzes the characteristics of spatial evolution of rural residential land from 2006 to 2017 in terms of scale,shape,density and distribution by using the landscape index in landscape ecology,and it compares the of spatial variation characteristics of rural residential land between karst villages and non-karst villages;and it analyzes influencing factors of spatial evolution of rural residential land from three aspects of nature,location,economic and social conditions;It is constructed by geographically weighted regression model to explore the direction and the impact of various factors on the spatial evolution of rural residential land in different regions of the county,and identify the dominant factors affecting rural residential areas in karst areas.The main conclusions are as follows:(1)According to the definition of natural villages,remote sensing images,administrative divisions,ridges,rivers and roads are overlapped by using ArcGIS software and natural villages are divided on the basis of administrative villages.The basis for dividing karst village is the proportion of karst landform area,which is karst village when the proportion exceeds60%.The results show that there are 1490 natural villages,in Pingguo County,including 1058 karst villages,and 432 non-karst villages,.(2)The spatial evolution of rural residential land in the county are mainly reflected in:(1)the scale of rural residential land is obviously increased,and the patch shape index of rural residential land changes more smoothly,but its irregular degree is higher,and the density of it shows a growth trend,and it shows the distribution of agglomeration,but the degree of agglomeration is weakened.(2)From the point of view of the smallest research unit,the scale of rural residential land of natural village in Pingguo County has increased,but the scale is mainly small-sized;the irregular degree of the shape of rural residential land in Pingguo County has increased,and the irregular degree of the shape of the central region has changed greatly;the degree of spatial agglomeration of rural residential land of natural village in Pingguo County has gradually increased,and the spatial agglomeration of the south-central region has been significantly enhanced.(3)There are differences in the variation of rural residential land between karst and non-karst villages;the scale of rural residential land in karst villages has increased and is in a small scale;the irregularity of its shape is greater but the evolution of its degree is smaller;its spatial agglomeration has been strengthened and the degree of its agglomeration in the south-central region has been significantly enhanced;the scale of rural residential land in non-karst villages is smaller in a whole,and the scale of rural residential land in the southwest region is smaller and the degree of variation in the southwest region is larger than that in the northwest region.Its shape is irregular and the degree of variation has larger,and the degree of its spatial agglomeration is obviously enhanced.(3)The natural villages and the spatial variation of rural residential land are greatly influenced by natural factors such as elevation,slope and water source which have a low-medium value;the river has a greater impacton non-karst villages than karst villages.The influence of road on the spatial variation shows an increasing trend with the passage of time,and the directivity of road of non-karst villages is stronger.The radiation scope of town is mainly within 7500 meters.The small-scale of rural households and the increase of per capita income of rural residents promote the expansion of farmers' housing demand,which will enhance the impact of spatial variation in rural residential land.(4)Using the geographic weighted regression model,this paper studies the influencing factors and direction of various factors of the spatial variation of rural residential land in different regions of Pingguo County,and identifies the dominant factors affecting the spatial variation of rural residential land in Karst areas.The results showed that:(1)the spatial variation of rural residential land was positively correlated with the low elevation area and the low slope area.The specific manifestation was that the low elevation area gradually declined from the middle to the north and the low slope area in space.The spatial variation of rural residential land is mainly positively correlated with the distance from karst water point,road and town center,and the range of action from karst water point shows the spatial distribution characteristics of "north-high-south-low",while the range of action from road presents the characteristics of "north-high-south-low".The spatial distribution of "high in the South and low in the north" tends to weaken gradually in the south-central area,while its spatial variation is less affected by rivers.(2)The dominant factors of spatial variation of rural settlements in karst areas are elevation,slope and road.Among them,elevation is the most important factor affecting spatial variation of rural settlements in Karst and non-karst areas.Secondly,slope and road have the same impact on its spatial variation in karst areas,while road is the second factor and slope is the third factor in non-karst areas. |
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