Characteristic Scale And Multi-scale Spatial Association Analysis Of Land Components In Hunan Province

Scale is the measure of space or time used to study an object or phenomenon.The spatial hierarchy and autocorrelation of the elements of the land determine the spatial characteristics of each element.Wavelet,as a new multi-scale analysis method,has been applied to multi-scale,multilevel and multi-resolution problems in recent years.Based on the theory of landscape ecology and field survey data,this paper selects Hunan as a mesoscale research area,and Xiangtan as a small scale research area,and selects four elements of terrain,vegetation,soil and human activities as the research object,and construct provincial scale and city scale sample line.Based on ArcGIS,the database of DEM(elevation data model),NDVI(normalized vegetation index),SOM(soil organic matter)content and LUI(land use intensity index)is used to extract the data of various land components on the sample line by multi-scale analysis sample line method.The wavelet analysis method is used to calculate the wavelet variance and the wavelet coherence coefficient between the elements in the MATLAB environment,and the correlation between the characteristic scales and the factors is obtained respectively.By analyzing the characteristics scale of the elements of land composition in the study area and the multi-scale spatial correlation,the hierarchy,regularity and correlation of the spatial distribution of the elements can be revealed,which can provide the scientific basis for improving the classification of land classification levels,the evolution process of land spatial distribution,and the selection of evaluation indexes of land use.It will provide new knowledge and technology for land science.The main results and conclusions are as follows.(1)There are three scales in the spatial distribution patterns of the elements in the mesoscale and small scale research areas: 0-20 km,20-50 km and >50km,0-8km,8-15 km and >15km.(2)The strongest observation scale of the heterogeneity of the elements of the Hunan research area is that the characteristic scales are around 20 km and 50-70 km,and the characteristic scales of the elements of the land components in the Xiangtan research area are distributed around 5km,10 km and 17 km.(3)The spatial distribution of surface vegetation is mainly restricted by human activity and soil organic matter content on the sample line of river crossing river system,and the spatial heterogeneity of the ground surface vegetation on the undulating sample line is more affected by the topography.(4)In the scope of this study,the spatial distribution of the surface vegetation is more influenced by the factors of soil and human activity in view of the terrain factors.(5)The characteristic scale 20 km of each component of the land is consistent with the characteristic scale of the city,which can be used to test the suitability and scientificity of this study,and provide the basis for the research and exploration of the scale.