Abstract: Strong human activities due to urbanization have led to the spatial differentiation of soil carbon (C), nitrogen (N), phosphorus (P) concentrations and their ecological stoichiometry in green space. With soil samples at the depth of 0-10 cm and 10-20 cm being collected fromseven sites (centered on Wuxing Garden) along an urban-suburb-rural gradient in Nanchong, we analyzed the concentrations and ecological stoichiometry of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP). The results showed that the concentrations of SOC and TP in the green space soil had a decreasing tendency with the increase of distance from the downtown, while TN concentration showed no significant variation. The concentrations of SOC, TN and TP decreased with increasing soil depth in the green space of each site, with stronger trend for SOC and TN. Soil C∶N and C∶P of green space, obviously lower than average value at national level, tended to decrease along the urban-suburb-rural gradient. Soil N∶P of green space, which was lower than the average value at national level, had an increasing tendencyalong the urban-suburb-rural gradient. Compared to the average value of non-urban soil at national level, the stoichiometry of C, N and P were seriously imbalanced in the urban soils of Nanchong.

Key words: urban-suburb-rural gradient, C∶N∶P, ecological stoichiometry, Nanchong.