DOI: 10.5061/dryad.sn02v6x16
title: Disentangling the effects of methanogen community and environment on peatland greenhouse gas production by a reciprocal transplant experiment

description: 1. Northern peatlands consist of a mosaic of peatland types that vary
 spatially and temporally and differ in their methane (CH4) production.
 Microbial community composition and environment both potentially control
 the processes that release carbon from anoxic peat either as CH4 or carbon
 dioxide (CO2), a less potent greenhouse gas than CH4. However, the
 respective roles of these controls remain unclear, which prevents
 incorporating microbes in the predictions of peatland CH4 emissions. 2.
 Here, a reciprocal transplant experiment was carried out to separate the
 influences of microbial community and environment in CH4 and anaerobic CO2
 production. Peat from an acidic Sphagnum bog and a sedge fen with higher
 pH was enclosed in membrane bags with a pore size of 0.2 µm, preventing
 microbial colonization from the outside, and transplanted in the field for
 two months. 3. Potential CH4 production was primarily controlled by the
 environment. The conditions in the bog suppressed the initially higher
 activity of fen methanogens and reduced CH4 production by 79%. Against
 expectations, the inhibition was not specific to acetate-using
 Methanotrichaceae. Reciprocal transplantation favoured Methanosarcinaceae
 and potentially methylotrophic methanogenesis in general. Bog methanogens,
 mostly hydrogenotrophic Methanoregulaceae, retained their community
 structure and activity in the fen with a slight increase (+37%) in CH4
 production. 4. Anaerobic CO2 production was controlled by both the
 microbial community and the environment. Transplantation led to increased
 CO2 production in both bog (+50%) and fen peat (+57%) with distinct
 bacterial community, showing that the new environment directed more carbon
 to other anaerobic processes than methanogenesis. 5. Taken together, these
 results relate differences in CH4 production of bogs and fens to
 ecophysiology of specific methanogen groups. The sensitiveness of fen
 methanogens to the acidic conditions in Sphagnum bogs can help explain the
 decrease of CH4 emission in the typical boreal peatland succession from
 young fens to older bogs. Increase in anaerobic CO2 vs. CH4 production
 with transplantation shows that disturbances of boreal peatlands can
 activate poorly defined pathways of anaerobic decomposition.
description: This dataset includes data from a reciprocal transplant
 experiment in the field between a bog and a fen in the boreal Lakkasuo
 peatland complex in Finland. Peat was transplanted from the bog to the fen
 and from the fen to the bog for 57 days. At the end of the experiment, the
 transplanted peat samples and control transplants within the bog and
 within the fen were analyzed in the laboratory for methane production
 potential, anaerobic carbon dioxide production potential, pH, number of
 <em>mcrA</em> transcripts by quantitative PCR (file data1),
 and methanogen communities by RNA-based <em>mcrA</em> T-RFLP
 (file data2). In addition, untransplanted native peat at the beginning
 and the end of the experiment was analyzed. For details of the methods,
 please see Juottonen (2020).
description: Variables in the dataset are explained in the readme file.