δ^(13)C值在羊草草原植物体中的差异和变化及其影响因素分析

Analysis of Differences and Influencing Factors of Plant δ^(13)C in Leymus chinensis Grassland in Inner-Mongolia,China

为了解稳定同位素^(13)C在草原植物体中的分配和变化以及水分和温度对^(13)C组成(δ^(13)C)的影响,在内蒙古羊草草原的生长盛期(7-9月),应用^(13)C脉冲标记技术,测定了^(13)C脉冲标记处理和对照处理下羊草草原植物活体和活根中的δ^(13)C,分析了土壤水分、气温和地温对植物体中δ^(13)C的影响。结果表明:对照处理中羊草草原植物活根δ^(13)C值比活体高1～2‰,标记处理中活体δ^(13)C值显著高于活根,标记处理中活体和活根的δ^(13)C均显著高于对照处理。生长盛期,标记和对照处理中植物活体和活根的δ^(13)C值均表现为先减小再增加,随后再减小的趋势。对照处理中活体和活根以及标记处理中活根的δ^(13)C与0～20cm土壤水分含量之间线性负相关,而标记处理中活体δ^(13)C与0～20cm土壤水分之间存在二次函数关系。标记、对照两处理中羊草草原活体、活根δ^(13)C与温度均呈线性正相关。

In order to understand the distribution and change of stable carbon isotope 13C in grassland plants and the effects of soil moisture and temperature on the stable carbon isotope 13C composition(δ13C),we measured theδ13C of shoots and living roots which both had two treatments,13C pulse labeling treatment and control treatment,and analyzed the effect of soil moisture content,air temperature and ground temperature on theδ13C of plants body during the fast-growing stage(July-September)of the Leymus chinensis grassland in Inner Mongolia.The results showed that theδ13C of the living roots was 1~2‰higher than theδ13C of the shoots in control treatments,and theδ13C of the shoots in13C pulse labeling treatment was significantly greater than theδ13C of the living roots.The variation trends of theδ13C value of shoots and living roots in labeling and control treatments were both in good consistency with time,which showed that the value of13C in shoots and living roots decreased at first,then increased,and then decreased during the growing season of plants.Theδ13C of the shoots and living roots in control group and living roots in 13C pulse labeling treatment had a linear negative correlation with soil moisture content in the layer of 0~20 cm,but theδ13C of shoots in 13C pulse labeling treatment had Quadratic function relation with the soil moisture content in the layer of 0~20 cm,which indicated that theδ13C increased with increasing soil moisture content when it had a low soil moisture content,and theδ13C decreased when there was a high soil moisture content.In13C pulse labeling treatment and control treatment,there were significant positive correlation between temperature and theδ13C of the shoots and living roots,theδ13C of the shoots and living roots increased with increasing the temperature.