Impacts of impervious surface expansion on soil organic carbon – a spatially explicit study

The rapid expansion of impervious surface areas (ISA) threatens soil organic carbon (SOC) pools in urbanized areas globally. The paucity of field observations on SOC under ISA (SOC(ISA)), especially in dryland areas has limited our ability to assess the ecological impacts of ISA expansion. Based on systematically measured SOC(ISA) (0–80 cm depth) of a dryland city, and land-use and land-cover change data derived from remotely sensed data, we investigated the magnitude and vertical/horizontal patterns of SOC(ISA) and mapped the impact of ISA expansion on SOC storage. The mean SOC(ISA) in the city was 5.36 ± 0.51 kg C m(−2), lower than that observed in humid cities but much higher than that assumed in many regional carbon assessments. SOC(ISA) decreased linearly as the soil depth or the horizontal distance from the open area increased. SOC(ISA) accounted for over half of the city’s SOC stock, which decreased by 16% (primarily in the converted croplands) because of ISA expansion from 1990 to 2010. The impacts of the ISA expansion varied spatially, depending on the land- use and converted land-cover type.