中文摘要：

在人类活动和气候变化的双重影响下,青藏高原高寒湿地生态系统发生巨大变化,尤其是引起地气间水能循环过程发生改变.基于高寒沼泽草甸布置的3处样地（OTC-1、OTC-2和Control）一年的观测数据,分析短期增温对活动层土壤温度变化过程的影响.结果表明：OTC-1和OTC-2年均气温分别增加了6.7℃和3.5℃,日间气温增加显著,而夜间气温基本保持不变,从而加大了气温日较差.增温促进植物的生长发育,使OTC内地上生物量要显著高于室外.OTC-1年平均地温要明显高于室外,而OTC-2地温与室外基本相当,这些主要受到OTC结构及植被热隔绝作用的影响.OTC-1总积温随着深度的增加不断降低,且在5cm、20cm深度总积温为正值,而OTC-2和Control在土壤浅层略有降低,65cm深度以下基本趋于一致.该研究结果将对研究高寒生态系统水热过程和碳排放具有一定的参考价值.

英文摘要：

Climate change is now evident in the Tibetan Plateau,with impacts on the alpine ecosystem,particularly on heat-water processes within the active layer,due to the effects on water and heat balance between the permafrost surface and the atmosphere.For this reason,the influence of global warming on heat-water processes was studied through one-year observation in three sample plots,OTC-1,OTC-2 and Control.OTC-1 and OTC-2 were open-top chambers,manipulated with the mean annual air temperature increment of 6.7 ℃ and 3.5 ℃,respectively,and Control without manipulation as a contrast.The relative humidities of OTC-1 and OTC-2 were 8.0% and 6.2%,less than that of Control.Day temperature increased sharply whereas night temperature unchanged in OTC,causing much large diurnal temperature amplitude.Warming promoted plant growth and development,resulting in a significantly higher aboveground biomass in OTC-1 and OTC-2.The beginning date of active layer freezing postponed and the beginning date of thawing occurred earlier,shortening the durations of entirely frost period and frozen days.The fully thawed period extended and the thawed days increased too.Annual mean soil temperature of OTC-1 was obviously higher than that of Control,whereas there was no significant difference between OTC-2 and Control.The main reason is the effects of OTC structure and vegetation isolation.Moreover,the total cumulative temperature under all manipulations is negative,except for that at 5 cm and 20 cm depths in OTC-1.The total cumulative temperature of OTC-1 decreased with the depth.However,the total cumulative temperature of OTC-2 and Control decreased in a shallow layer only.These results are useful to studying water-heat process and carbon emission of alpine cold ecosystem.