城市绿地年龄对土壤有机碳积累的影响

Effects of green space age on organic carbon accumulated in urban soils

为了了解城市土壤有机碳积累的空间变化规律,从杭州市采集了48个点的绿地土样,采用化学和生物学分析方法研究了城市绿地土壤有机碳全量、颗粒状有机碳、黑碳、微生物生物量碳含量和代谢熵等随城市绿地年龄的变化。结果表明:与其他陆地生态系统相似,城市环境下人为的强烈干扰一旦停止和成土条件相对稳定后,绿地土壤将向一定方向发展;随着城市绿地年龄(即保持相对稳定的绿地景观的持续时间)的增加,土壤容重下降,有机碳全量和黑碳逐渐积累,并趋向稳定,土壤微生物生物量碳及其占有机总碳的比例逐渐增加,而代谢熵(qCO2)明显降低;表明作为成土因素之一的时间因素在城市绿地土壤演变和性质空间变异上起着重要的作用;随着人为干扰停止及城市绿地景观形成时间的增加,土壤受人为干扰的影响也逐渐减弱。

In order to understand the spatial pattern of organic carbon accumulated in urban soils, 48 different age green spaces in Hangzhou City were selected, and their soil total organic C, particulate organic C, black C, microbial biomass C, and metabolic quotient （ratio of basal respiration to microbial biomass） were determined. Once the anthropogenic activities ceased or the soil-formation conditions were stable, the urban soils developed toward a certain direction, similar to other terrestrial ecosystems. With the increase of green space age, the accumulation of soil organic C, particulate organic C, microbial hiomass C and black C increased, while the soil bulk density and metabolic quotient decreased, indicating that as one of the soil-formation factors, time played an important role in the spatial variation of the physical, chemical, and biological properties of urban soils. It was recognized that with the cessation of human disturbance and the increase of green space age, the impact of urbanization on urban soil properties was gradually weakened.