Abstract: Abstract: 【Objective】 This study aimed to evaluate the effects of urban tree species on the vertical distribution of carbon and nitrogen and soil organic carbon storage, generating basic data for use in the selection of urban tree species in afforestation.【Method】 Soil organic carbon(SOC)and total nitrogen(TN)contents, as well as SOC storage at different soil depths were determined under urban monoculture stands of three tree species(i.e., Metasequoia glyptostroboides, Cinnamomum camphora and Bischofia polycarpa). These indices were compared with those of the nearby farmland.【Result】① SOC and TN contents under tree stands were species specific, they varied from 7.28 to 10.78 g/kg and from 1.03 to 1.43 g/kg, respectively, and were significantly higher under B. polycarpa stand than that under M. glyptostroboides and C. camphora stands. Throughout the three stands, soil C/N ratio varied from 4.78 to 9.56, and significantly differed between M. glyptostroboides and B. polycarpa. ② SOC storage was also species specific, ranging from 60.54 to 89.61 t/hm² among the stands(B. polycarpa > C. camphora > M. glyptostroboides). ③ There was a significantly positive correlation between SOC and TN contents at all sites. In addition, SOC and TN contents were significantly positively correlated with clay content, but negatively correlated with soil bulk density. ④ SOC content, TN content and SOC storage were significantly lower under M. glyptostroboides, C. camphora and B. polycarpa stands compared to those in the farmland; the soil C/N ratio was significantly different between the tree stands and the farmland in the 7^th year after afforestation. Compared to that under M. glyptostroboides stand, the soil C/N ratio value under C. camphora and B. polycarpa stands, was much closer to that under farmland.【Conclusion】 Overall, the SOC and TN contents, as well as SOC storage decreased at different rates during the early period of conversion of farmland to forest. This study showed that B. polycarpa, a broadleaf tree species, is more suitable for the early recovery and sequestration of SOC in response to land use change, compared with other urban species.