青藏高原高寒湿地温室气体释放对水位变化的响应

为了探究水位变化对青藏高原高寒湿地温室气体释放的影响,以高原东部若尔盖典型高寒湿地为研究对象,采用“中型实验生态系”的技术手段,研究了两种不同水位情形 稳定水位(SW,0 cm)和波动水位(DW,从0 cm下降到45 cm,再复原到0 cm)] 对高寒湿地二氧化碳(CO₂)、甲烷(CH₄)和氧化亚氮(N₂O)三种温室气体释放的影响。结果表明,1)高寒湿地水位变化对土壤(0~10 cm)可溶性有机碳(DOC)没有显著影响;水位从0 cm下降到45 cm,再复原到0 cm,对铵态氮(NH4+-N)和硝态氮(NO3--N)的转化起到了促进作用;2)水位变化对高寒湿地CO₂释放影响不显著,SW和DW处理下CO₂累积释放量分别为235.2和209.7 g/m²;3)水位变化对CH₄释放有显著影响,CH₄累积释放量从SW处理的1.79 g/m²下降到DW处理的0.86 g/m²,下降了52.18%;4)水位波动处理抑制了N₂O的释放,其在SW和DW条件下的累积释放量分别是6.72和-7.36 mg/m²;5)高寒湿地土壤温度在10 ℃以上,CO₂和CH₄释放量与其呈显著正相关性,水位下降提高了CO₂和CH₄释放与温度的拟合度。

Responses of greenhouse gas emissions to water table fluctuations in an alpine wetland on the Qinghai-Tibetan Plateau

A mesocosm experiment was conducted to study the effect of water table level on greenhouse gas (CO2 ,CH4 ,N2 O)emissions in alpine wetland on the Qinghai-Tibetan Plateau.Two treatments were adopt-ed;stable water table (SW;about 0 cm or at soil surface)and dynamic water table (DW;0 cm reducing to 45 cm and returning to 0 cm).The results showed that alpine wetland water table changes had no significant effect on soil dissolved organic carbon (DOC),but promoted transformations of ammonium (NH4 +-N)and nitrate (NO3 --N).The cumulative emissions of CO2 were 235.2 and 209.7 g/m2 for SW and DW treatment,respec-tively but were not significantly different.However,there was a significant treatment difference on CH4 emis-sions.Cumulative emission of CH4 for DW (0.86 g/m2 )decreased by 52.18%,compared with SW (1.79 g/m2 ).The cumulative emission of N2 O for SW (6.72 mg/m2 )was significantly higher than that for DW (7.36 mg/m2 ).There was a positive correlation between CO2/CH4 release and soil temperature in the alpine wetland with soil temperatures below about 10 ℃.The drop in the water table increased the sensitivity of CO2/CH4 release to soil temperature.Models of the response of CO2 ,CH4 and N2 O emissions to water table chan-ges were different in alpine wetland on the Qinghai-Tibetan Plateau.