排水对若尔盖高寒沼泽CO2和CH4排放通量的影响

建立3块标准样地（天然沼泽、1990s和1970s排水沼泽），于2014年生长季期间，采用静态箱-快速温室气体分析仪野外原位观测CO₂和CH₄排放通量.结果表明：沼泽排水增加了土壤温度（5，20，45cm），但降低沼泽水位；1990s（680±329）mg CO₂/（m²·h）]和1970s排水沼泽（973±234）mg CO₂/（m²·h）]生态系统CO₂排放通量分别较天然沼泽增加了200%和330%，但CH₄排放通量（0.78±0.52）mg CH₄/（m²·h）]和（-0.01±0.02）mg CH₄/（m²·h）]较天然沼泽分别降低了90%和100%；综合考虑两者排放通量，1990s（186±89）mg C/（m²·h）]和1970s排水沼泽（265±64）mg C/（m²·h）]生态系统碳（C）排放通量较天然沼泽分别增加了180%和300%.天然沼泽、1990s和1970s排水沼泽生态系统CO₂排放通量与5cm土壤温度存在显著正相关，而仅1990s排水沼泽生态系统CO₂排放通量与水位存在显著负相关.天然沼泽生态系统CH₄排放通量与土壤温度（5，20，45cm）存在显著正相关，但1970s排水沼泽生态系统CH₄排放通量与土壤温度（20，45cm）存在显著负相关，1990s排水沼泽生态系统CH₄排放通量与水位存在显著正相关.沼泽排水显著增加了若尔盖高寒沼泽生态系统C排放通量，降低了沼泽C汇功能，可能增强区域气候变暖.

Effects of drainage on the CO2 and CH4 emission fluxes in the Zoigê Plateau Marsh

The CO₂ and CH₄ emission fluxes in the Zoigê Plateau Marsh were monitored by using the dark static chamber and Fast Greenhouse Gas Analyzer at three typical sampling sites (natural marsh, drainage marshes in the 1990s and 1970s) from May to October in 2014. The results showed that the drainage increased the soil temperature (5, 20 and 45cm depth) and reduced the water level. The ecosystem CO₂ emission fluxes of the drained marshes in 1990s(680±329) mg CO₂/(m²·h)] and 1970s(973±234) mg CO₂/(m²·h)] were 200% and 330% higher than that in the natural marsh. While, the ecosystem CH₄ emission fluxes of the drained marshes in 1990s(0.78±0.52) mg CH₄/(m²·h)] and 1970s(-0.01±0.02) mg CH₄/(m²·h)] were 90% and 100% lower than that in the natural marsh, respectively. Taking into consideration of both CO₂ and CH₄ emission fluxes, the ecosystem carbon (C) emission fluxes of the drained marshes in 1990s(186±89) mg C/(m²·h)] and 1970s(265±64) mg C/(m²·h)] were 180% and 300% higher than that in the natural marsh. Besides, there was a significant positive correlation between the ecosystem CO₂ emission fluxes and the soil temperature of 5cm depth in the three typical sampling sites. Whereas, there was an obvious negative correlation between the ecosystem CO₂ emission flux and the water level in the 1990s drained marsh. In addition, the ecosystem CH₄ emission flux in the natural marsh was notably positively correlated with the soil temperatures at 5, 20 and 45cm depth. However, the ecosystem CH₄ emission flux in the 1970s drained marsh was remarkably negatively correlated with the soil temperatures at 20 and 45cm depth. Meanwhile, we also found that there was a significant positive relation between the ecosystem CH₄ emission flux in the 1990s drained marsh and the water level. This research suggested that the marsh drainage could significantly increase the ecosystem C emission flux from the soil into the atmosphere in the Zoigê Plateau Marsh, subsequently decrease the soil C sink function, and further enhance the regional climate warming.