荒漠草原土壤有机质碳稳定同位素特征研究

Research on Characteristics of Soil Stable Carbon Isotope Composition in Desertification Grassland

应用碳稳定同位素分析方法对内蒙古短花针茅荒漠草原土壤有机质及其δ13 C值垂直分布特征、表土δ13C值与建群种-短花针茅δ13 C值的相互关系进行分析,并测定土壤部分理化性质。结果显示:表土有机质含量变化范围为4.17～20.45g/kg;随深度增加,土壤有机碳(SOC)含量呈指数降低,其变化范围为17.98～1.39g/kg,而δ13C值则随剖面深度增加而明显富集,到75cm深度时δ13C值又迅速降低,变化范围为-26.38‰～-13.72‰,变幅>3‰,说明该地区气候和植被状况可能发生过剧烈变化;表土和植物δ13C值分馏程度较其它地区偏大,二者呈极显著相关(r=0.555,P<0.01),进一步说明地上植被状况是影响土壤有机质δ13 C值垂直分布特征的决定性因素。

Characteristics of soil stable carbon isotope composition and relationship between δ13C value of soil on surface and δ13C value of Stipa breviflora were analyzed by using carbon stable isotope technology in Stipa breviflora desertification grassland in Inner Mongolia,soil physical and chemical properties were also tested.The results showed that the content of soil organic carbon（SOC） of soil on surface changed between 4.17 g/kg and 20.45 g/kg;the content of SOC decreased dramatically with the increase of soil depth,it changed from 17.98 g/kg to 1.39 g/kg.However,an conspicuous enrichment of δ13C value happened with the increase of soil depth until 60 cm,in the depth of 60-75 cm,δ13C value dropped to-26.38‰,and the amplitude 3‰,which suggested that radical changes in climate and vegetation could have happened;the fractionation between plants and soil on surface was lager than it in other areas.Besides,a significant correlation between them was observed,and the result provided further information on that the vegetation was the decisive factor which affected the spatial distribution characteristics of δ13C value of SOC.