低丘红壤有机碳库的密度及变异

DENSITY OF SOIL ORGANIC CARBON POOL AND ITS VARIATION IN HILLY RED SOIL REGION

在中国科学院红壤生态实验站,采样分析了不同利用方式下土壤有机C 库的密度及其变异.结果表明,低丘红壤有机C 的密度0～20cm为(2.09 ± 0.69) kg/m2,0～100 cm为(5.01 ± 1.46) kg/m2; 全N密度0～20 cm为(0.20 ± 0.07) kg/m2, 0～100 cm为(0.59 ± 0.14) kg/m2.从裸地到稀疏荒草地,0～20 cm和0～100 cm土壤有机C 密度可以提高1.0 kg/m2和1.7 kg/m2;而从稀疏荒草地到人工林地或园地,0～20 cm和0～100 cm土壤有机C 密度可以提高0.7 kg/m2和0.9 kg/m2;稀疏荒草地如果开垦利用为水田,经长期培肥达到高度熟化,则0～20 cm和0～100 cm土壤有机C 密度可以提高2.3 kg/m2和4.4 kg/m2.即使不同类型的人工林地和园地之间,0～20 cm和0～100 cm土壤有机C 的密度差异也可达到1.0 kg/m2和3.5 kg/m2.不同地形部位之间0～20 cm和0～100 cm土壤有机C 密度差异达到1.3 kg/m2和2.9 kg/m2,全N密度差异达0.1 kg/m2和0.3 kg/m2;不同肥力水平之间0～20 cm和0～100 cm土壤有机C 密度差异达到1.5～2.2 kg/m2和2.8～4.1 kg/m2,全N密度差异达0.07～0.11 kg/m2和0.20～0.23 kg/m2; 强烈侵蚀可以降低0～20 cm和0～100 cm土壤有机C 密度1.4 kg/m2和2.2 kg/m2.因此,通过调整土地利用方式,可以提高土壤有机C 库密度,增加固定大气CO2潜力.

Density of soil organic C pool and its variation in the soils under different types of landuse were investigated through field sampling and chemical analysis at the Ecological Experimental Station of Red Soil, Chinese Academy of Sciences. Results showed that in hilly red soil organic C density was (2.09 0.69) kg/m2 and (5.01 1.46) kg/m2, and total N density (0.20 0.07) kg/m2 and (0.59 0.14) kg/m2, in the soil layer of 0~20cm and 0~100cm in depth, respectively, which varied with the landuse. Soil organic C density in the soil layer of 0~20cm and 0~100cm in depth increased by 1.0kg/m2 and 1.7kg/m2 in sparse grassland compared to that in bare land, by 0.7kg/m2 and 0.9kg/m2 in artificial forest or orchard compared to that in sparse grassland, and by 2.3kg/m2 and 4.4kg/m2 in paddy field of high fertility compared to that in sparse grassland. Differences also existed in organic C density being 1.0kg/m2 and 3.5kg/m2 between different types of artificial forests and orchards. The difference between profiles in organic C density being 1.3kg/m2 and 2.9kg/m2 and in total N density being 0.1kg/m2 and 0.3kg/m2, and between soils different in fertility in organic C density being 1.5~2.2kg/m2 and 2.8~4.1kg/m2 and in total N density being 0.07~0.11kg/m2 and 0.20~0.23kg/m2. Intensive erosion could decrease soil organic C density by 1.4kg/m2 in the soil layer of 0~20cm and by 2.2kg/m2 in the soil layer of 0~100cm in depth. Therefore, rationalization of land use could increase the density of soil organic C pool and enhance the potential of sequestrating atmospheric CO2 in soil.