中文摘要：

采用开顶式生长室（OTC）模拟增温实验,研究了川西北亚高山草甸植物群落碳、氮含量对温度升高的响应。由于OTC的增温作用,在整个生长季内,地温（15cm）、地表温度和气温（30cm）的平均值在OTC内比对照样地分别高0.28、0.46和1.4℃,OTC内土壤相对含水量也明显减少,低于对照样地5.49%。受增温及土壤含水量减少的影响,一年后,植物群落的生物量积累和碳、氮含量发生了明显的改变。除10月份OTC内地上鲜体生物量略高于对照样地外,OTC内地上鲜体生物量和根系生物量与对照样地相比,都出现了不同程度的减少;OTC内植物群落地上活体的碳浓度在整个生长季高于对照样地,而氮浓度低于对照样地;OTC内植物群落地下活根的碳浓度在整个生长季高于对照样地,并且在8月份统计检验显著,而氮浓度却低于对照样地;OTC内植物碳库在整个生长季较对照样地有不同程度的增加,增幅范围为0.90%～5.65%,而OTC内植物氮库较对照样地有不同程度的减少,减幅范围0.40%～1.28%。

英文摘要：

From 2006 to 2007, a total number of 5 open top chamber （ OTC ） experiments were carried out in the sub-alpine meadow of northwestern Sichuan province, and the effects of the OTCs on temperature, soil water content, plant biomass accumulation, and on carbon and nitrogen content were examined. In the growing season, the mean soil temperatures at depth of 15 cm and of ground surface and the air temperature at 30 cm above ground were enhanced by 0.28, 0.46 and 1.4℃, respectively by the OTC facility. However, soil water content in OTC was 5.49% lower than that in the control one. With the warming and drying effect, plant biomass accumulation, carbon and nitrogen content of the sub-alpine meadow obviotisly changed. The above-ground live biomass and below-ground root biomass both decreased in the OTC plots compared to the control plots during the growing season except that the aboveground live biomass increased a little in October. The C concentration of above-ground live in the OTC plots was higher than that in the control plots throughout the growing season, while the N concentration in the OTC plots was lower than that in the control plots. The C concentration of below-ground root in the OTC plots was also higher than that in the control plots throughout the growing season, and a significant difference was detected in August, while the N concentration in the OTC plots was also lower than that in the control plots. The C stock in the OTC plots increased compared to the control plots, and ranged from 0.90% to 5.65%, while the N stock in the OTC plots decreased compared to the control plots, and ranged from 0.40% to 1.28%.