The influence of urbanization on organic carbon sequestration and cycling in soils of Beijing

Using 231 soil sampling sites established during August and September 2012, we investigated the characteristics of soil organic carbon (SOC) in urban soils of Beijing and examined the carbon stocking capability as well as the relationship between urbanization indicators and SOC characteristics. The urban soils of Beijing can be characterized by a shortage of SOC, a weak level of microbial activities but efficient respiration of soil microbes. The capability for carbon stacking is limited, and the process of urbanization has enhanced carbon cycling in the urban soils. The landscape is regarded as the primary factor accounting for the variation of SOC in the urban soils of Beijing. The results of correlation analysis and kinetic fittings show that urbanization presents a positive effect on SOC stocking, and SOC stocks increase with urbanization. SOC characteristics would reach a the stable stage, although urbanization indicators continue to change, meaning that the urban soils of Beijing have a mechanism by which to maintain balance within soil ecosystem.