Study on soil organic carbon pool at foreststeppe zone of loess plateau

Forest soil organic carbon (SOC) is the largest organic carbon pool in terrestrial ecosystem. It is of great significance for the carbon balance of the earth. The content of SOC, soil organic carbon density (SOCD) and relationship between influence factors of two naturally grown forests, Pinus tabulaeformis f. shekannesis and Quercus liaotungensis, and an artificially planted forest, P. tabulaeformis, were studied in Ziwuling forest area of the Loess Plateau. The means of SOCD were 10.76, 11.43 and 9.38kg/m2, respectively. SOCD decreased significantly as soil depth increased (P0.05). SOCD in three forests was different significantly. SOCD in the whole soil profile was positive correlated significantly with soil moisture，TN, TP, potassium and AN, but negative correlations with soil pH value.