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研究局域尺度土壤有机碳空间分布特征,对准确估算大尺度土壤碳库储量和变化具有重要意义。以黄土丘陵沟壑区典型小流域为对象,采集0-10、10-20、20-40、40-60、60-80、80-100cm土层中(898个土壤样品),采用多元线性逐步回归和地理信息系统(GIS)相结合方法,分析了地形(峁顶、峁坡、沟底)、土地利用(农田、果园、川坝地、草地、灌木林、乔木林)等作用下,小流域不同深度土壤有机碳含量的空间分布特征。结果表明:地形因素不仅对表层(0-10cm)土壤有机碳含量空间分布差异影响显著,而且对深层(40-100cm)影响也显著,且空间格局图上40-100cm可以清晰地看地沟底与峁顶和峁坡显著差异。在0-10cm土层,峁顶以中值斑块(50%)和低值斑块(48%)为主;峁坡以中值斑块(62%)为主,其次是低值斑块(22%);沟底中值斑块占70%,其次为低值斑块(23%)。40-100cm均为低值斑块,沟底低值绿色斑块占34%,远高于峁坡(8%)和峁顶(13%)。土地利用对表层(0-40cm)有机碳含量影响显著,对40-100cm土层无影响。在0-10cm土层,乔木林、灌木林、草地上高值斑块分别占18%、47%、10%,川坝地、农田和果园没有高值斑块,中值斑块分别占80%、53%、85%、73%、39%、23%。10-40cm土层,乔木林、灌木林、草地、川坝地、农田和果园中值斑块分别占21%、46%、22%、19%、5%、4%。但在40-100cm土层,各土地利用下有机碳均处于低值斑块区。坡向上0-100cm各层土壤有机碳含量半阴坡(北部、东北、东部)最高,半阳坡(西部、西南、南部)含量较低。
Studying the spatial distribution characteristics of soil organic carbon at the local scale is of great significance for accurate estimation of the large-scale storage and change of soil carbon stocks. Taking typical small watersheds in the hilly and gully regions of the Loess Plateau for example, 898 soil samples were collected from 0-10, 10-20, 20-40, 40-60, 60-80 and 80-100 cm soil layers, and multivariate linear stepwise regression And Geographic Information System (GIS), the effects of topography (top, slope and bottom of ditch), land use (farmland, orchard, chuanba, grassland, shrubbery and arbor) Spatial distribution characteristics of soil organic carbon at different depths. The results showed that the topographic factors not only had a significant effect on the spatial distribution of soil organic carbon in the surface layer (0-10cm), but also had significant effects on the depths of 40-100cm (40-100cm) Significant differences between the top and the slope. In the 0-10cm soil layer, the top of the top is dominated by the median patch (50%) and the low patch (48%). The main patch is the median patch (62%), followed by the low patch (22%). The median ditch was 70%, followed by the low value (23%). 40-100cm are low-value patches, 34% of low-value green patches at the bottom of the ditch are much higher than the slopes of 8% and 13%. Land use had a significant effect on the organic carbon content of the surface layer (0-40cm), but had no effect on the soil layer of 40-100cm. In the 0-10cm soil layer, the high-value patches on the arbor, shrubbery and grassland account for 18%, 47% and 10% respectively. There is no high-value patch in the farmland and orchard, %, 53%, 85%, 73%, 39%, 23%. The median patches of 10-40 cm soil layer, arbor forest, shrubbery, grassland, chuanba, farmland and orchard accounted for 21%, 46%, 22%, 19%, 5% and 4% respectively. However, in the 40-100 cm soil layer, the organic carbon in each land use is in a low-value patch area. Soil organic carbon content in all layers from 0-100 cm in the slope was highest in the semi-shady slope (north, northeast and east) and low in the semi-sunny slope (west, southwest and south).