Abstract: Global warming seriously affects the carbon and nitrogen cycled ecosystems. Understanding the carbon and nitrogen cycle of alpine grassland ecosystems is extremely important for the rational use of limited grassland resources. To explore the carbon and nitrogen cycle of grassland ecosystems in the context of global warming, this paper uses OTC (Open top champers) warming chambers to simulate warming for four consecutive years, and evaluates the carbon pools of alpine grassland ecosystems (plant biomass carbon pools, soil organic carbon pools) on the Qinghai-Tibet Plateau and soil microbial biomass carbon pool) dynamic changes and nitrogen pool (plant biomass nitrogen pool, soil organic nitrogen pool and soil microbial biomass nitrogen pool) dynamic changes. The results showed that:After the simulated temperature increased, the average annual temperature of the surface soil increased by 2.50℃, and the average annual temperature of the bottom soil increased by 1.36℃. The plant-soil-microbial biomass carbon content under warming treatment was hiher than that of the control, and the soil microbial biomass carbon content was significantly higher than that of the control (P<0.05). The nitrogen content of plants under the simulated warming treatment was significantly higher than that of the control (P<0.05). The soil nitrogen content and microbial biomass nitrogen content were lower than that of the control, although the difference was not statistically significant.

Key words: Alpine meadow, Simulated warming, Carbon cycle, Nitrogen cycle

摘要： 全球变暖严重影响着草地生态系统碳氮循环，了解高寒草地生态系统碳氮循环对合理利用有限的草地资源有着极为重要的意义。为了探索全球气候变暖的背景下草地生态系统碳氮循环过程，本文采用开顶式增温小室（Open top champers，OTCs）连续四年模拟增温，对青藏高原高寒草地生态系统碳库（植物生物量碳库、土壤有机碳库和土壤微生物生物量碳库）动态变化及氮库（植物生物量氮库、土壤有机氮库和土壤微生物生物量氮库）动态变化进行研究。结果显示：模拟增温后，表层土壤年均温度增加了2.50℃，底层土壤年均温度增加了1.36℃。增温处理下植物-土壤-微生物生物量碳含量均高于对照，且土壤微生物生物量碳含量显著高于对照（P<0.05）。模拟增温处理下植物氮含量显著高于对照（P<0.05）。而土壤氮含量与微生物生物量氮含量均低于对照，差异不显著，说明高寒草甸碳氮对温度的响应较为明显。

关键词: 高寒草甸, 模拟增温, 碳循环, 氮循环