顾及空间自相关的地理国情信息统计格网尺度选择——以植被覆盖信息统计为例

Scale Selecting of Geographic National Conditions Information Statistical Grids with Spatial Autocorrelation ——A Case Study of Vegetation Cover Information Statistics

统计格网尺度的不同会带来统计结果的差异,如何选择统计格网是地理国情信息统计的重要工作。本文提出了一种顾及空间自相关的地理国情信息统计格网尺度选择方法。采用地理国情普查数据,在50 m、60 m、70 m、80 m、90 m、100 m、250 m、500 m和1000 m几个尺度下,以植被覆盖信息统计为例,利用面积占优法和中心点归属法两种方法分别进行格网化,得到了不同尺度的植被格网数据;计算植被覆盖面积统计误差,分析不同尺度下植被覆盖信息的空间自相关的变化特征,并利用Moran’s I系数差值进行尺度选择,得到了植被覆盖信息统计格网的适宜尺度。以龙沙区和清涧县作为研究区域,结果表明,在地理国情植被覆盖信息统计时,不同地区的格网统计适宜尺度是不一样的,植被覆盖度中低的龙沙区的适宜尺度为100 m,而植被覆盖度高的清涧县的适宜尺度为250 m。

The difference in statistical grid scales will bring different statistical results, so it is important to select statistical grids for the geographical conditions information statistics. A method of choosing statistical grids scale of geographical conditions information with spatial autocorrelation being taken into account is proposed. By using geographic conditions census data and taking vegetation cover information statistics as an example, the study gets vegetation cover girds data, under the rule of maximum area and the rule of centric cell in scales of 50 m, 60 m, 70 m, 80 m, 90 m, 100 m, 250 m, 500 m and 1000 m, and meanwhile calculates vegetation cover statis- tical errors, analyzes changes of spatial autocorrelation of vegetation cover gird data at different scales to make scale selection, and then uses vegetation cover statistical errors to obtain an appropriate statistical grid scale of vegetation cover information statistics. The results show that for vegetation cover information statistics of geographic national conditions, the suitable scale is 250 m in areas with high degree of vegetation coverage, and 100 m in areas with low degree of vegetation coverage.