Abstract: Open top chambers (OTCs) were used to simulate the elevated CO₂ concentrations (350 and 700 μmol·mol^-1) and changing precipitation (-30%，-15%，0，+15% and +30%). The content of organic carbon and total nitrogen,and its accumulations in shoot and root of Reaumuria soongarica were measured in this study. Results showed that:The responses of organic carbon and total nitrogen contents,organic carbon accumulations in shoot and root and total nitrogen accumulations in shoot of R. soongarica to changes of CO₂concentration and precipitation were significant,and interactive effects were observed. Doubled CO₂ concentration significantly increased organic carbon contents,C/N and organic carbon accumulations in shoot and root,and total nitrogen accumulations in shoot. With increased precipitation,organic carbon contents and accumulations in shoot and root,and total nitrogen accumulations in root increased,shoot and root C/N exhibited a trend of first decreasing and then increasing,shoot total nitrogen contents exhibited a trend of first increasing and then decreasing. These results showed that when CO₂ concentration increases in the future,interaction of elevated precipitation and higher CO₂ concentration would contribute to the accumulation of organic carbon in R. soongarica plants,thus promots the absorption of nitrogen by R. soongarica plants. Decreased precipitation is beneficial for R. soongarica plants to adjust their carbon and nitrogen balance and improving their drought resistance.

Key words: CO₂ concentration, Precipitation change, Organic carbon, Total nitrogen, C/N, Carbon-nitrogen cycle

摘要： 本研究以荒漠优势植物红砂（Reaumuria soongorica） 1年生幼苗为研究对象，采用开顶式生长箱（Open top chambers，OTCs）模拟CO₂浓度变化（350和700 μmol·mol^-1），研究了降水变化（-30%，-15%，0，+15%和+30%）及其协同作用对红砂地上和地下部分碳、氮含量与积累量的影响。结果发现：CO₂浓度倍增和降水对红砂地上和地下部分有机碳、全氮含量和有机碳积累量以及地上全氮积累量影响极显著，并且表现出极显著的交互作用。CO₂浓度倍增下，红砂地上和地下部分有机碳、C/N和有机碳积累量以及地下部分全氮显著增加。随着降水增加，红砂地上和地下部分有机碳含量和积累量以及地下部分全氮均呈增加趋势，地上和地下部分C/N呈先降后升趋势，而地上部分全氮先升后降。综上所述：未来CO₂升高时，降水增加协同高CO₂浓度有助于红砂植株有机碳积累，从而促进红砂植株对氮素的吸收，降水减少则有利于红砂调节自身碳氮平衡从而提高其抗旱性。

关键词: CO₂浓度, 降水变化, 有机碳, 全氮, C/N, 碳氮循环