坡耕地黑土有机碳空间异质性及其格局

Spatial Heterogeneity and Pattern of Black Soil Organic Carbon of Sloping Field

在250m×100m研究区域上以10cm间隔网格采样,用地球同步技术卫星自动聚焦水准仪测定采样点位置及坡度,用重铬酸钾—硫酸容量法测定SOC含量。用地统计学理论(半方差函数及Kriging插值)对SOC数据进行分析,结果表明坡耕地SOC在不同方向上存在很大的空间异质性。不同土层SOC的空间相关性存在很大的差异,随着土壤深度增加空间相关性减弱,主要原因是土壤发生因素,尤其是地形因素起着决定性作用。施肥,纵向打垄及耕翻等土壤管理方式降低了SOC空间的相关性,使其随机性增强,SOC呈均一化方向发展。用克立格(Kriging)插值法绘制坡耕地SOC含量分布图,发现SOC含量与地形及土壤发生过程尤其是土壤再分布过程密切相关。坡肩部位侵蚀最为严重,SOC含量最低;坡度相似的坡顶和坡背SOC含量相近。就整个研究区来看,高含量的SOC转变为中等含量和低含量的SOC,充分揭示SOC在量上的变化机理。

<Abstrcat> We collected soil samples from an area of 250 m×100 m and detemined location of sample and slope using Geostationary Technology Satellite Auto focus, the content of SOC were analyzed by method of K2CrO7-H2SO4 capacity. The data were analyzed based on Geostatistics method (Semivariance and Kriging interpolation) and the conclusion showed that SOC of sloping field had strong spatial heterogeneity at different aspect. There were an obvious spatial correlation among SOC of different soil layers, and the correlation weaken with soil depth increase. The reason may be soil-forming factors especially landform play a crucial role; soil management such as fertilization, ridge vertical to contour line and cultivation decreased this correlation and increased its randomicity, which made SOC tend to uniformity. The content of SOC had a strong relationship with landscape units and soil forming process especially soil redistribution based on distribution maps of SOC produced by Kriging interpolation. The content of SOC at shoulder-slope was lowest because of serious erosion; summit and back-slope had similar content of SOC due to similar slope. The mechanism of SOC change at the whole study area was put forward, namely SOC with high content was changing into SOC of middle and low content.