土壤碳库研究中土壤数据从矢量到栅格的等精度转换

矢量数据转换成栅格数据是多数区域土壤碳库研究中数据准备的关键步骤。本研究以太湖地区1:5万、1:50万、1:400万3个比例尺土壤矢量数据库为基础,分别转成不同分辨率的栅格数据;基于不同比例尺和栅格分辨率数据,研究水稻土表层(0～20cm)的土壤类型数量、面积、有机碳储量以及有机碳密度变化,并以矢量数据获得的这4个指标为基准,用相对变异百分数(VIV)来判别不同栅格数据与其对应比例尺土壤矢量数据之间的精度差异。结果表明,在4个指标的|VIV|<1%前提下,3个比例尺矢量数据分别转换成0.2km×0.2km、1km×1km、9km×9km的栅格数据,既保证数据转换过程中精度要求,又避免了数据冗余。土壤数据比例尺与栅格分辨率等精度转换对应关系可描述为y=0.0225x-0.01233(R²=0.999),对区域土壤碳循环研究具有重要参考价值。

Study on the transformation from vector to raster for soil data with identical data precision in the estimation of Soil Organic Carbon Stocks

Soil data transformed from vector to raster data is an important step for data preprocessing in most researches on regional soil carbon stocks.Based on 3 scales of soil vector databases,which are 1:50,000,1:500,000 and 1:4,000,000,a series of raster datasets with different resolutions were converted from these soil vector data.Four indices,soil type number,soil area,soil organic carbon stocks and soil organic carbon density of surface paddy soils(0-20cm)were calculated from all these vector and raster datasets respectively.Subjected to the 4indices from vector data,their relative variability(VIV,%)from raster datasets was used to assess soil data identity between the soil vector data in different scales and their responding raster datasets,respectively.Results show that optimal resolutions of raster datasets converted from these three vector data in different map scales are 0.2km×0.2km,1km×1km and 9km×9km respectively,due to the VIV of all the indices less than 1%,in which soil vector data and the responding raster dataset have an identical data precision.The optimal resolution raster data can not only meet the requisements of data precision in SOC stock researches,but also avoid data redundancy and resources wasting.The relationship between soil vector map scale and the optimal raster resolution under an identical data precision can be modeled as follows:y=0.0225x0.01233(R²=0.999),which can provide valuable reference for research on soil organic carbon stocks at regional scale.