摘要：Empirical evidence shows that the expansion of impervious surface threatens soil organic carbon (SOC) sequestration in urbanized areas. However, the understanding of deep soil excavation due to the vertical expansion of impervious surface remains limited. According to the average soil excavation depth, we divided impervious surface into pavement (IS<sub>20</sub>), low-rise building (IS<sub>100</sub>) and high-rise building (IS<sub>300</sub>). Based on remote-sensing images and published SOC density data, we estimated the SOC storage and its response to the impervious surface expansion in the 0–300 cm soil depth in Guangzhou city, China. The results showed that the total SOC storage of the study area was 8.31 Tg, of which the top 100 cm layer contributed 44%. The impervious surface expansion to date (539.87 km<sup>2</sup>) resulted in 4.16 Tg SOC loss, of which the IS<sub>20</sub>, IS<sub>100</sub> and IS<sub>300</sub> contributed 26%, 58% and 16%, respectively. The excavation-induced SOC loss (kg/m<sup>2</sup>) of IS<sub>300</sub> was 1.8 times that of IS<sub>100</sub>. However, at the residential scale, renovating an IS<sub>100</sub> plot into an IS<sub>300</sub> plot can substantially reduce SOC loss compared with farmland urbanization. The gains of organic carbon accumulation in more greenspace coverage may be offset by the loss in deep soil excavation for the construction of underground parking lots, suggesting a need to control the exploitation intensity of underground space and promote residential greening.
