Relationship between soil organic carbon distribution and soil properties among three woodlands at Ice Valley in the upper reaches of Heihe basin

The experiment was conducted to determine the relationship between soil organic carbon distribution and soil properties among three woodlands at Ice Valley in the upper reaches of Heihe basin, Qilian County of Qinghai Province. This study showed that the average organic carbon density at 0-60 cm layer was sorted as coniferous forest＞forest thicket＞broad-leaved forest. The organic carbon density was 7.18 kg·m-2 in coniferous forest, and was 1.24 times of shrubbery and 1.58 times of broadleaved forest. The soil organic carbon density at 0-10 cm layer was 13.22, 9.49 and 8.62 kg·m-2 in coniferous forest, forest thicket and broadleaved forest, respectively, and was 1.84, 1.63, and 1.89 times of organic carbon density of total soil profile, respectively. The moisture content, aggregate and total nitrogen at 0-60 cm layer was sorted as following order, coniferous forest＞forest thicket＞broadleaved forest, while bulk density, physical grains of sand and pH value was coniferous forest＜forest thicket＜broadleaved forest. The correlation analysis showed that the soil organic carbon content was positively related to natural moisture content, aggregate, and total nitrogen (P<0.05), however, it was negatively related to bulk density, physical grains of sand and pH in three woodlands (P<0.05).