不同高寒草甸土壤碳氮稳定同位素和密度的差异  

Variations in soil carbon and nitrogen stable isotopes and density among different alpine meadows

作　　者：全小龙 段中华[1,2] 乔有明[1] 裴海昆[2] 陈梦词 何桂芳[1] 

机构地区：[1]青海大学生态环境工程学院,青海西宁810016 [2]青海大学分析测试中心,青海西宁810016 [3]青海畜牧兽医职业技术学院农林科学系,青海西宁812100

出　　处：《草业学报》2016年第12期27-34,共8页Acta Prataculturae Sinica

基　　金：国家自然基金项目(31260573);青海省科技厅国际合作项目(2012-H-806);教育部创新团队(IRT13074)和教育部美大项目(2014)资助

摘　　要：为了解不同类型高寒草甸土壤碳氮稳定同位素和密度的差异,采用稳定同位素质谱仪Isoprime100对采自黄河源区不同高寒草甸覆被条件下0~30cm土壤进行了碳氮稳定同位素组成特征和密度分析。结果表明,高寒草甸土壤δ13 C值介于-25.42‰^-24.20‰之间,δ15 N值介于3.37‰~4.69‰之间,显著高于大气δ15 N值。δ13 C值和δ15 N值均随土壤深度加深而增大。人工草地土壤δ13 C值显著低于轻度和重度退化草甸(P<0.05),而δ15 N值显著高于轻度和重度退化草甸(P<0.05)。土壤碳氮比最小值为7.89,最大值为9.97,平均碳氮比为8.71。土壤有机碳含量和全氮含量呈正相关(P<0.01),二者的回归方程为y=0.0963x+0.0336(R2=0.9619)。轻度退化草甸、严重退化草甸和人工草地0~30cm土壤碳密度依次为7.14、6.67和6.46kg/m2;全氮密度依次为0.83、0.77和0.75kg/m2。植物吸收、生长有利于12 C和14 N的输出,而将较重的13 C和15 N留在了土壤中。人工草地植物生长势强,形成的地上生物量多,吸收了较多的土壤氮素14 N,导致土壤15 N升高。植被退化或种植人工草地均可导致土壤碳氮密度的显著降低,这种变化主要发生在0~20cm土层。As a new technology,stable isotope analysis has developed rapidly in the field of ecology in recent decades.However,this technology has not been used widely in studies on alpine meadows.The abundance of stable isotopes and the densities of carbon and nitrogen in soils（0-30cm）of different alpine meadows at the headwater region of the Yellow River were measured with Isoprime100.The soilδ^13 C ranged from-25.42‰to-24.20‰.The soilδ^15 N ranged from 3.37‰ to 4.69‰,which is significantly higher than that in the atmosphere.The abundance of bothδ^13C andδ^15 N in soil increased with soil depth.The soilδ^13C abundance was significantly lower in mix-seeded pasture soil than in soils of heavily and lightly degraded meadows（P〈0.05）,while the abundance ofδ15 N was significantly higher in mix-seeded pasture soil than in soils of heavily and lightly degraded meadows（P〈0.05）.The soil C∶N ratio ranged from 7.89 to 9.97.There was a significant（P〈0.01）positive correlation between soil organic carbon content and total nitrogen content,and the relationship could be expressed by the following regression equation：TN（%）=0.0963×SOC（%）＋0.0336（R^2=0.9619）.The soil organic carbon density in the 0-30 cm soil layer in the lightly degraded meadow,severely degraded meadow,and mix-seeded pasture was 7.14,6.67,and 6.46kg/m^2,respectively,and the total nitrogen density was 0.83,0.77,and 0.75kg/m^2,respectively.Plant absorption and growth facilitated the outputs of 12 C and 14 N,leaving the heavier ^13 C and ^15 N isotopes in the soil.Vigorous growth and higher above ground biomass in the mix-seeded pasture consumed more soil^ 14 N,resulting in higher concentrations ofδ^15 N in the soil.Alpine meadow degradation and establishment of mix-seeded pastures may significantly reduce the soil carbon and nitrogen density,and this change will be mainly restricted to the 0-20 cm soil layer.

关 键 词：黄河源区 草甸土壤 稳定同位素 碳氮密度 

分 类 号：S812.2[农业科学—草业科学]