上海城市绿地土壤肥力变化分析

Analysis on the Change of Soil Fertility in Shanghai Urban Green Space

城市绿地土壤是城市生态建设的基础,其质量和变化趋势直接影响城市绿地生态和景观效应。以2002、2014和2018年3次大规模的上海绿地土壤调查为基础,研究不同城市绿地土壤肥力的变化特征,旨在为城市绿地土壤的养分管理提供科学指导。结果表明:上海城市绿地土壤呈碱性,2002、2014和2018年土壤pH平均值分别为8.36、8.20和7.79;土壤速效养分(N、P、K)充足,3次取样均达到绿化种植土标准;土壤通气孔隙度较小,3次取样均小于绿化种植土标准阈值(5%)。从时间变化趋势上看,上海城市绿地土壤pH值在逐渐降低,土壤有机质含量在逐渐提高,土壤肥力综合指数也在逐渐提升;但土壤物理性质逐渐退化,容重逐渐增加,通气孔隙度逐渐变小。不同类型绿地间土壤肥力的变化趋势基本一致,其中受人为活动影响剧烈的附属道路绿地土壤容重和通气孔隙度自2002年起严重退化,与2018年无显著差异。

The soil of urban green space is the foundation of urban ecological construction,and its quality and change trend directly affect the ecological and landscape effect of urban green space.Based on three large-scale surveys of green land soil in Shanghai in 2002,2014 and 2018,the changes of nutrients and comprehensive fertility of different green space soil were analyzed,in order to provide scientific guidance for nutrient management of urban green space soil.The results showed that the soil of urban green space in Shanghai was alkaline,and the average soil pH value in 2002,2014 and 2018 were 8.36,8.20 and 7.79,respectively.The soil available nutrients(N,P,and K)were sufficient.The soil porosity was small,and the three samples were lower than the standard threshold of green planting soil(5%).From the point of view of time change trend,the soil pH value of urban green space in Shanghai is gradually decreasing,the content of soil organic matter is increasing gradually,and the comprehensive index of soil fertility is also increasing gradually.However,the physical properties of green space soil degrade gradually,the bulk density of soil increases gradually,and the porosity of soil decreases gradually.Between different types of green space,the change trend of soil fertility is basically the same.The soil of road was severely affected by human activities,and the soil bulk density and porosity had seriously degraded since 2002,which was not significantly different from that in 2018.