中文摘要：

基于国际冻原计划（ITEX）模拟增温效应对植物影响的研究方法,以高寒矮嵩草草甸4种植物（矮嵩草、垂穗披碱草、棘豆、麻花艽）为实验材料,设置大（OTC1）和小（OTC2）两类增温小室,测定了其叶片碳氮及其稳定性碳同位素（δ^（13）C、δ^（15）N）等指标在增温3年后的变化。结果表明：除矮嵩草在较小增温小室（OTC2）中C/N比值比对照降低了14.1%,其它物种C/N在两个增温处理下都有所增加,但差异均不显著（P〉0.05）。4种植物叶片δ^（13）C值在-24.12‰~-28.34‰之间,矮嵩草叶片δ^（13）C值随增温而升高,棘豆、麻花艽随增温而降低,且矮嵩草在OTC2的δ^（13）C值变化达到显著水平（P〈0.05）。矮嵩草和麻花艽的叶片δ^（15）N值在OTC1和OTC2中均比对照增加,且麻花艽增加较显著（P〈0.05）。垂穗披碱草在OTC1和OTC2的叶片δ^（15）N值比对照分别减少18.7%和26.9%,差异都不显著（P〉0.05）;棘豆叶片δ^（15）N值在OTC2内比对照低11.0%（P〉0.05）,在OTC1的内比对照高2.8%（P〉0.05）。可见,高寒矮嵩草草甸不同功能群植物物种碳氮含量及稳定性碳氮同位素含量对短期增温有不同的响应模式和规律。

英文摘要：

Based on the research methods that simulated warming effect on plants of tundra plan （ITEX）,we used four kinds of plants at alpine Kobresia hurnilis meadow. K. humilis, Elymus nutans, Oxytropis ochrocephala, Gentiana straminea, set a big（OTC1） and a small（OTC2） warming room, to determine the carbon, nitrogen and their stability isotopes（δ13C,δ15N） content changes after three years of warming. The result showed that. in addition to the C/N ratio of K. humilis was reduced by 14.1% in small warming room （OTC2）, the C/N ratios of the other three species were all increased in the two warming rooms than that in the control, while the differences were all not significant（P〈0.05）. The 813C of the four kinds of plant leaves was between --24.12 % -28.34 %, the δ13C of K. humilis leaf was increased with raising temperature, while the 813C of O. ochrocephala and G. straminea was reduced with the raising tempera- ture. The 813C change of K. humilis leaf reached significant level（P〈0.05）. The 815N δ13. humilis and G. straminea were all increased in the two warming rooms than that in the control, the 815N change of G. strarninea reached significant level （P〈0.05） ; the 815N change of E. nutans reduced 18.7% and 26.9% in OTC1 and OTC2 respectively, while the differences were all not significant （P〉0.05） ; the δ13N change of O. ochrocephala was reduced by 11.0% in small warming room （OTC2） than that in control, while in creased by 2.8% in big warming room （OTC1） than that in control. It is observed that the carbon, nitro- gen and their stability isotopes （δ13C,δ15N） of different functional group of plant species have different re- sponse patterns and rules to short-term warming.