采用高度分别为0.4 m(OTC-1)和0.8 m(OTC-2)的开顶式增温小室(open top champers,OTCs),对青藏高原高寒草甸生态系统进行模拟增温处理,研究了高寒草甸生态系统的CO2排放强度及过程对气温升高的响应。结果表明:在平均气温分别提高1.25℃(OTC-1)和3.68℃(OTC-2)的条件下,对照及2种不同幅度增温处理高寒草甸生态系统 CO2排放通量表现出明显的季节变化特征,并同时在植被生长旺盛期(78月)达到峰值,分别为2.31、2.35和6.38mumol·m-2·s-1;CO2排放通量在不同季节都表现出随增温幅度的升高而逐渐增大的趋势,表明随着气温升高,CO2排放通量逐渐增大;不同处理CO2排放通量与气温、5 cm土壤温度和5 cm土壤含水量之间表现出显著的相关关系,CO2排放通量与气温及5 cm土壤温度之间均符合指数关系,而与5 cm土壤含水量之间则符合二次多项式关系。

Two open-top chambers(OTCs)with height 0.4 m(OTC-1)and 0.8 m(OTC-2)were used to simulate the global warming and to study the effects of elevated temperature on the CO2 flux during growth season in an alpine meadow ecosystem in Qinghai-Tibetan Plateau.The OTC-1 and OTC-2 had an increased mean annual temperature 1.25℃and 3.68℃,respectively,compared with the control.In the control,OTC-1 and OTC-2,the CO2 fluxes all showed an evi-dent seasonal variation,and peaked at vigorous growth stage(from July to August),being 2.31,2.35,and 6.38mumol·m-2·s-1,respectively.At different growth stages,the CO2fluxes all showed an increasing trend with the increment of temperature,indicating that global warming could cause the increase of CO2 flux in alpine meadow.The CO2 fluxes in the control,OTC-1 and OTC-2 all had significant correlations with air temperature and the soil temperature and moisture at the depth of 5 cm.The correlations between the CO2 emission fluxes and the air temperature and soil temperature were exponential,and those between the CO2 emission fluxes and soil mois-ture were quadric multinomial.