Installation of impervious surfaces in urban areas has attracted increasing attention due to its potential hazard to urban ecosystems. Urban soils are suggested to have robust carbon (C) sequestration capacity; however, the C stocks and dynamics in the soils covered by impervious surfaces that dominate urban areas are still not well characterized. We compared soil organic C (SOC) densities and their stabilities under impervious surface, determined by a 28-d incubation experiment, with those in open areas in Yixing City, China. The SOC density (0–20 cm) under impervious surfaces was, on average, 68% lower than that in open areas. Furthermore, there was a significantly (P<0.05) positive correlation between the densities of SOC and total nitrogen (N) in the open soils, whereas the correlation was not apparent for the impervious-covered soils, suggesting that the artificial soil sealing in urban areas decoupled the cycle of C and N. Cumulative CO2-C evolved during the 28-d incubation was lower from the impervious-covered soils than from the open soils, and agreed well with a first-order decay model (C t = C 1+C 0(1-e -kt)). The model results indicated that the SOC underlying capped surfaces had weaker decomposability and lower turnover rate. Our results confirm the unique character of urban SOC, especially that beneath impervious surface, and suggest that scientific and management views on regional SOC assessment may need to consider the role of urban carbon stocks.
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机译:由于其对城市生态系统的潜在危害,在城市地区安装不透水表面已引起越来越多的关注。建议城市土壤具有强大的碳(C)固存能力;然而,仍不能很好地描述主导城市地区的不透水表面所覆盖的土壤中的碳库和动力学。我们比较了在28天的孵化实验中确定的不透水表面下土壤有机碳(SOC)的密度及其稳定性,并将其与中国宜兴市的空旷地区进行比较。防渗表面下的SOC密度(0–20 cm)平均比空旷地区低68%。此外,在开阔土壤中,SOC密度与总氮(N)之间存在显着(P <0.05)的正相关,而在不透水的土壤中,这种相关性并不明显,这表明城市中的人工土壤封闭区域解耦了C和N的循环。在28天的温育过程中,从不透水的土壤中累积的CO2-C低于从开放的土壤,并且与一阶衰减模型(C t = C 1 + C 0(1-e -kt sup>))。模型结果表明,加盖的表面下的SOC具有较弱的可分解性和较低的周转率。我们的研究结果证实了城市SOC的独特性,特别是在不透水的表面之下,并暗示科学和管理观点对区域SOC评估可能需要考虑城市碳储量的作用。
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