上海城市绿地土壤有机碳、全氮分布特征

选择上海市中心城区公园、道路、街头等样地,研究了城市绿地土壤有机碳、全氮的分布特征及其在不同利用方式下各土壤剖面的含量变化。结果表明:上海城市绿地土壤有机碳、全氮平均含量分别为11.21、1.06 g/kg,其中有机碳含量以0～10 g/kg和10～20 g/kg为主,分别占全部的47.18%、47.18%,全氮含量以0.5～1.0 g/kg和1.0～1.5 g/kg为主,分别占全部的49.56%和39.80%;与上海市郊区农田土壤相比,中心城区绿地土壤有机碳平均含量低5.68g/kg,幅度为33.63%,全氮平均含量低0.89 g/kg,幅度为45.64%;与第2次土壤普查上海数据相比,上海中心城区绿地土壤有机碳含量下降了10.19 g/kg,降幅为47.62%,全氮含量下降了0.18 g/kg,降幅为14.52%。不同利用方式下城市绿地土壤有机碳、全氮含量从大到小顺序为公园、街头、道路,且差异主要与人为养护水平有关;城市绿地土壤有机碳、全氮含量随剖面深度增加呈下降趋势,且表层均显著高于下层(p<0.05)。回归分析表明,城市土壤有机碳、全氮之间满足显著线性关系,符合方程y=0.056 3x+0.430 5。研究结果表明,提高土壤养护水平,降低人为活动影响强度是增加城市绿地土壤有机碳、全氮的重要途径。

Distribution characteristics of soil organic carbon and total nitrogen in greenbelt soil in Shanghai center city

The distribution characteristics of soil organic carbon(SOC) and total nitrogen of greenbelt soil in Shanghai center city were studied,and the content of urban greenbelt soil under different land use patterns and soil profile were also analyzed.The results showed that the average content of SOC and nitrogen of greenbelt soil in Shanghai center city were 11.21 and 1.06 g/kg in which the content of SOC between 0—10 g/kg and 10—20 g/kg were accounted for 47.18 % and 47.18 %,and the content of nitrogen between 0.5—1.0 g/kg and 1.0—1.5 g/kg were accounted for 49.56 % and 39.80 %.Compared to the farmland soil in Shanghai suburb,the content of SOC and nitrogen in the urban greenbelt soil were decreased 5.68 and 0.89 g/kg,and the decreasing degree were 33.63 % and 45.64 %,respectively.Compared to the second soil survey,the content of SOC and nitrogen in the urban greenbelt soil decreased 10.19 and 0.18 g/kg,respectively,and the decreasing degree were about 47.62 % and 14.52 %.The sequence of SOC and nitrogen under different land use patterns was park soil > street soil > road soil,and the difference was mainly related with the level of soil maintaining;In the soil profile,the content of SOC and nitrogen were decreased along with the increasing of soil layers,and the surface layer was significantly higher than the lower layer;Regression analysis showed that there exited a significant linear relationship between SOC and nitrogen,and fitted to the equation y=0.056 3x+0.430 5.These data illustrated that increasing the level of soil maintaining and decreasing the human impacts on urban greenbelt soil was an important way to increase the content of SOC and nitrogen.