Abstract:

Different forests for water and soil conservation in Simian Mountain of Chongqing were selected for field experiment to study soil organic carbon (SOC) content in 0~20,20~40 and 40~60 cm and SOC density to different soil depths.Results showed that the mean SOC content in 0~20,20~40 and 40~60 cm was 33.09, 7.51 and 3.21 g/kg,respectively.The SOC density to the depth of 20 cm ranged from 4.97 to 14.31 kg/m2,and that to 60 cm ranged from 7.84 to 17.94 kg/m2 with the mean of 12.78 kg/m2 in forest stands for water and soil conservation.With increasing soil depth,SOC content and density decreased significantly,but the decrease varied with tree species composition.Significant differences were found for SOC density to the depth of 60 cm in different forest stands,which decreased in the order of natural secondary forests > plantations for water and soil conservation > agricultural land.The highest SOC density (17.94 kg/m2) was found in the natural broadleaved mixed forest,and the lowest one (7.84 kg/m2) in the agricultural land.Among plantations for water and soil conservation,the highest SOC density was found in the broadleaved mixed plantation.Therefore,broadleaved mixed plantation is suggested to be established to increase SOC