2005年1~5月在青藏高原北麓河附近的高寒干草原、高寒草甸和高寒草原3种典型草地上进行了不同深度土壤气体采样和CO2浓度分析.结果表明:土壤剖面的土壤气体CO2浓度呈现出上低下高的分布特征.在动态变化上,土壤中CO2浓度在多年冻土活动层春季升温过程中出现一个峰值,经过短暂的降低后随夏季融化过程开始而升高.土壤剖面CO2浓度与土壤有机碳、重组有机碳、轻组有机碳、水溶性有机碳、植物残体有机碳、微生物碳贮量和土壤温度呈明显的相关关系,在100cm以上深度与土壤水分呈负相关关系.在整个观测期间,高寒干草原、高寒草原和高寒草甸植被下3种土壤剖面土壤气体CO2浓度变化范围分别为1052-3050mL·m^-3、3425-39144mL·m^-3和984~12250mL·m^-3,高于我国壤土CO2浓度变化范围,也远远高于青藏高原五道梁地区高寒草原土壤气体CO2浓度变化范围.石灰简育寒冻雏形土和石灰寒冻砂质新成土CO2浓度变化范围低于国外报道的草地和农田CO2浓度变化范围;石灰草毡寒冻雏形土CO2浓度变化范围明显高于国外报道的草地和农田CO2浓度变化范围.活动层冻结期,土壤CO2的闭蓄作用比较明显.由于微地形导致土壤水分条件的差异,夏季融化过程各观测点土壤CO2浓度开始升高时间存在差异.
To estimate the dimension of CO2 producing and letting in permafrost regions of the Tibetan Plateau, alpine dry grassland (Cab-Gel-Sandic Entisols), alpine meadow grassland (Cab-MatCryic Cambisols) and alpine grassland (Cab-HapCryic Cambisols) in Beiluhe Region were chosen for study. The distribution characteristics of CO2 conceration in soil profiles and the CO2 concentration in the soils at different times were studied in three sites. The results showed that there existed similitude for the distribution characteristics of CO2 concentration in the three soil profiles, decreasing gradually from top to bottom. The soil CO2 concentration has a peak in the spring warming, with a short dropping afterwards, and then rises with summer melting. But the time of rising has difference, which maybe caused by the dissimilarity of water condition. The CO2 concentration in soil profile has significant correlativity with the total organic carbon (TOC), the heavy form of organic carbon (HFOC), the light form of organic carbon (LFOC), carbon in debris, water--deliquescent organic carbon (WDOC), the microbe carbon (MB--C) and the soil water (0-100 cm). The ranges of CO2 concentration changed successively from 1052 to 3050 mL · m^-3 in Cab-Gel-Sandie Entisols, from 3425 to 39144 mL · m^-3 in CabMat-Cryic Cambisols and from 984 to 12250 mL · m^-3 in Cab-Hap-Cryic Cambisols. These are larger than the range of CO2 concentration in Chinese Loutu soil and the soil under alpine grassland in Wudaoliang region of the Tibetan Plateau, and differ from the range of CO2 concentration in soil of farmland and grassland that has been reported. With global warming, the CO2 concentration in permafrost active layer will change the CO2 concentration of atmosphere, to which more attention should be pay.