湘西州植烟土壤有效铜时空变异特征研究

Temporal and spatial variation characteristics of available Cu in tobacco planting soil in Xiangxi state

以湘西州2000年和2015年两个年份采集的土壤样品有效铜数据为研究对象,其中2000年土壤样品为446个,2015年为1 242个,采用经典统计学和地统计学的方法分析了湘西州烟区土壤有效铜的描述性统计特征、时空变异格局。结果表明,从基本统计特征和分布频率来看,15年间湘西州植烟土壤有效铜含量均值由1.05 mg/kg上升到1.89 mg/kg,上升幅度达80%,不同等级的土壤样品有效铜分布频率变化较大,与2000年相比,2015年土壤有效铜适宜等级的样品比例减少了32.35个百分点。同时,极低、低、高和极高等级的样品比例分别增加了1.93、1.49、12.00和16.93个百分点,表明烟区土壤有效铜含量增加的同时,呈现出两极分化的特点。从时空变异来看,15年间,土壤有效铜块金效应增大,随机性因素对土壤有效铜空间变异影响增强,土壤有效铜分形维数减小,表明有效铜呈现出更多较大尺度上的变异特点。从时空分布的变化来看,2015年土壤有效铜含量高和极高等级的面积增加明显,分别增加了33.94%和10.94%;而适宜等级则大幅下降,比2000年下降了45.01%。

The descriptive statistical characteristics and temporal and spatial variations of available copper in tobacco soils in Xiangxi state(western Hunan)were analyzed by classical statistics and geostatistics based on the data of soil samples collected in 2000 and 2015,and there were 446 soil samples in 2000 and 1 242 soil samples in 2015.The results showed that the average content of available copper in tobacco-growing soils in western Hunan increased from 1.05 mg/kg to 1.89 mg/kg in the past 15 years,with an increase of 80%.However,the distribution frequency of available copper in soil samples of different grades changed greatly.Compared with 2000,the ratio of samples of suitable grade of soil available copper in 2015 was higher.The number of cases decreased by 32.35 percentage points.At the same time,the proportion of extremely low,low,high and extremely high grade samples increased by 1.93,1.49,12.00 and 16.93 percentage points,respectively,indicating that the soil available copper content in tobacco growing areas increased at the same time,showing the characteristics of two-stage differentiation.From the perspective of spatial and temporal variability,the nugget effect of available copper in soil has increased in the past 15 years,and the random factors have enhanced the spatial variability of available copper in soil,and the fractal dimension of available copper in soil has decreased,which indicates that available copper has more large-scale variability characteristics.In terms of spatial and temporal distribution,the area of high and extremely high soil available copper content increased significantly in 2015,increasing 33.94%and 10.94%,respectively,while the suitable soil copper content decreased significantly,by 45.01%compared with 2000.