The role of Sphagnum mosses in the methane cycling of a boreal mire
The role of Sphagnum mosses in the methane cycling of a boreal mire
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DOI：
10.1890/09-1343.1
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发表时间：
2010-08-01
期刊：
影响因子：
4.8
通讯作者：
Fritze, Hannu
中科院分区：
文献类型：
--
作者：
Larmola, Tuula;Tuittila, Eeva-Stiina;Fritze, Hannu
泥炭地是大气甲烷（CH 4）的主要天然来源。泥炭藓为主的沼泽排放量低于其他沼泽类型的测量。这一观察结果可能部分是由于甲烷营养型（即，与泥炭藓有关的甲烷消耗）细菌。芬兰的41种泥炭藓中有23种可以在拉卡索的泥炭地找到。为了更好地理解泥炭藓-甲烷氧化菌系统，我们测试了以下假设：（1）所有这些泥炭藓物种支持甲烷氧化菌;（2）水位是不同生境甲烷氧化差异的关键环境决定因素;（3）在干燥条件下，泥炭藓物种不会宿主甲烷氧化菌;（4）甲烷氧化菌可以在水生环境中从一个泥炭藓芽移动到另一个。为了解决假设1和假设2，我们测量了Lakkasuo所有泥炭藓物种的地下水位和CH 4氧化，每个物种重复1-5次。使用这种系统的方法，我们包括泥炭藓属。有窄的和宽的生态容忍度。为了估计甲烷对苔藓碳的潜在贡献，我们测量了以甲烷或溶解在水中的二氧化碳形式提供的δ C-13的吸收。为了验证假设2-4，我们将不活跃的苔藓斑块移植到活跃的地点，并在移植前后测量了它们的甲烷氧化菌群落。所有23种泥炭藓都表现出甲烷氧化活性，证实了假设1。我们发现，水位是调节泥炭藓甲烷营养的关键环境因子（假设2）。以前没有表现出CH 4氧化的藓类植物在移植到对照藓类植物中的微生物正在积极氧化CH 4的环境中时变得活跃（假设4）。新的活性移植物具有甲基孢囊菌的特征，也发现在对照泥炭藓属物种。不活跃的移植也支持甲基孢囊菌的签名与活跃的移植和对照苔藓，拒绝假设3。我们的研究结果表明，泥炭藓属之间的松散共生。甲烷氧化菌可能占泥炭藓碳的10-30%。
Peatlands are a major natural source of atmospheric methane (CH4). Emissions from Sphagnum-dominated mires are lower than those measured from other mire types. This observation may partly be due to methanotrophic (i.e., methane-consuming) bacteria associated with Sphagnum. Twenty-three of the 41 Sphagnum species in Finland can be found in the peatland at Lakkasuo. To better understand the Sphagnum-methanotroph system, we tested the following hypotheses: (1) all these Sphagnum species support methanotrophic bacteria; (2) water level is the key environmental determinant for differences in methanotrophy across habitats; (3) under dry conditions, Sphagnum species will not host methanotrophic bacteria; and (4) methanotrophs can move from one Sphagnum shoot to another in an aquatic environment. To address hypotheses 1 and 2, we measured the water table and CH4 oxidation for all Sphagnum species at Lakkasuo in 1-5 replicates for each species. Using this systematic approach, we included Sphagnum spp. with narrow and broad ecological tolerances. To estimate the potential contribution of CH4 to moss carbon, we measured the uptake of delta C-13 supplied as CH4 or as carbon dioxide dissolved in water. To test hypotheses 2-4, we transplanted inactive moss patches to active sites and measured their methanotroph communities before and after transplantation. All 23 Sphagnum species showed methanotrophic activity, confirming hypothesis 1. We found that water level was the key environmental factor regulating methanotrophy in Sphagnum (hypothesis 2). Mosses that previously exhibited no CH4 oxidation became active when transplanted to an environment in which the microbes in the control mosses were actively oxidizing CH4 (hypothesis 4). Newly active transplants possessed a Methylocystis signature also found in the control Sphagnum spp. Inactive transplants also supported a Methylocystis signature in common with active transplants and control mosses, which rejects hypothesis 3. Our results imply a loose symbiosis between Sphagnum spp. and methanotrophic bacteria that accounts for potentially 10-30% of Sphagnum carbon.