Abstract: A study was made to investigate the contents of soil organic carbon(SOC)and its relations with soil physic-chemical properties in three age-group Chinese fir plantations in Fushou Forest Farm of Hunan Province.Results showed that the contents of SOC declined with the increase of soil depths in the soil of three forests.The contents of SOC in 0~15 cm soil layer was from 1.6 to 3.9 times as much as those in 15～30cm,from 2.4 to 4.6 times as much as those in 30～45cm and from 2.7 to 6.5times as much as those in 45～60cm,respectively.In 0～45cm soil layer,with the increasing age of Chinese fir plantations,changes of SOC contents varied in the order of mature>juvenile>middle aged forests in 0～45cm soil layer.A very significant positive correlation was found between soil SOC contents and the contents of total nitrogen,the contents of total phosphorous and C/N ratio showed significant positive correlations with soil SOC contents,while soil bulk density had a significant negative correlation with soil SOC contents.But the contents of soil total potassium and soil pH value had no significant correlations with soil SOC contents.

Key words: age-group, Chinese fir plantation, soil organic carbon, physic-chemical properties