增温对冻土区泥炭沼泽土壤孔隙水甲烷关联微生物和溶解性有机碳的影响

多年冻土区泥炭沼泽土壤孔隙水甲烷关联微生物及底物的研究有助于深入理解气候变化背景下寒区湿地生态系统甲烷循环过程。选取大兴安岭连续多年冻土区柴桦-泥炭藓和狭叶杜香-泥炭藓两种典型植被群落泥炭沼泽,设置开顶箱(Open Top Chamber,OTC)增温实验。于生长季(6月、7月、8月和9月)采集土壤孔隙水样品,对比分析OTC内外土壤孔隙水中产甲烷菌数量、甲烷氧化菌数量及溶解性有机碳(Dissolved Organic Carbon,DOC)浓度的动态变化特征,并探究土壤孔隙水甲烷关联微生物与DOC浓度的关系。结果表明:增温提高了生长季大兴安岭多年冻土区土壤孔隙水中产甲烷菌数量和DOC浓度,而对甲烷氧化菌数量的影响因月份而异。生长季柴桦-泥炭藓和狭叶杜香-泥炭藓泥炭沼泽土壤孔隙水中产甲烷菌数量的平均增加幅度分别为54.52%和44.97%,DOC浓度的平均增加幅度分别为34.16%和28.33%。增温使得生长季柴桦-泥炭藓和狭叶杜香-泥炭藓泥炭沼泽土壤孔隙水中甲烷氧化菌平均数量分别降低了46.20%和31.42%。一元线性回归分析结果表明,土壤孔隙水中DOC浓度可分别解释柴桦-泥炭藓和狭叶杜香-泥炭藓泥炭沼泽土壤孔隙水中产甲烷菌数量变化的29.00%和24.10%(P<0.01),而对两种植被群落下土壤孔隙水中甲烷氧化菌数量的影响并不显著(P>0.05)。

Effects of warming on abundances of methane-related microorganisms and concentration of dissolved organic carbon in soil pore water of permafrost peat swamp in Daxing'anling

Study of methane related microorganisms and substrates in soil pore water of peat swamp in permafrost regions is helpful to understand the methane cycle process of wetland ecosystem in cold regions under the background of climate change. In this study, the open top chamber (OTC) experiments were set up in two typical vegetation communities of Betula fruticosa-sphagnum and Ledum palustre-sphagnum peat swamp in continuous permafrost region of Daxing''anling. The abundances of methanogens, methane oxidizing bacteria and the concentration of dissolved organic carbon (DOC) in soil pore water inside and outside the OTC were compared and analyzed. The relationship between methane-related microorganisms and DOC in soil pore water was also explored. The results showed that warming increased the abundances of methanogens and the content of DOC in soil pore water in this region during the growing season, while the effect on the abundances of methane oxidizing bacteria varied with month. The average increase of the abundances of methanogens in soil pore water of Betula fruticosa-sphagnum and Ledum palustre-sphagnum peat swamp was 54.52% and 44.97%, and the average increase of DOC content was 34.16% and 28.33%, respectively. Warming reduced the average abundances of methane oxidizing bacteria in soil pore water of growing season of Betula fruticosa-sphagnum and Ledum palustre-sphagnum peat swamp by 46.20% and 31.42%, respectively. The results of one-variable linear regression analysis showed that the DOC content in soil pore water could explain 29.00% and 24.10% of the changes of methanogens in the Betula fruticosa-sphagnum and Ledum palustre-sphagnum peat swamp (P<0.01). However, there was no significant effect on the abundances of methane oxidizing bacteria in soil pore water under two vegetation communities (P>0.05).