Methane Emissions and Methanogenic Archaea on Pristine, Drained and Restored Mountain Peatlands, Central Europe

Abstract

Natural peatlands are known as an important source of methane (CH4). However, most peatlands in Central Europe were drained for forestry purposes in the past and some of them have been recently restored, both having a strong impact on CH4 emissions. The main aim of our study was to determine the effect of long-term drainage (a few decades) and hydrological restoration (3 years) on CH4 emissions, potential CH4 production and on the methanogenic Archaea community in different types of peatlands under various hydrological regimes. For this purpose, CH4 emissions together with biotic and abiotic variables were measured over three growing seasons, in vitro potential CH4 production was determined, and qPCR and DGGE fingerprinting were used for methanogenic community description in three ombrotrophic bogs (pristine, drained, restored) and two fens (pristine, drained) located in the Sumava National Park within the Bohemian Forest, Czech Republic. The highest CH4 emissions, CH4 potential production, and the highest diversity of the methanogenic community were observed in the pristine fen and bog. In the frame of interannual variability, a drought period seemed to play an important role in seasonal CH4 fluxes. Plant species composition together with water table seemed to be the most important factors controlling CH4 emission. Drainage led to a significant decrease in CH4 emissions, potential CH4 production, and the abundance and diversity of methanogens as compared to pristine sites. These post-drainage changes were more obvious in the fen site than on bog sites. However, none of the measured parameters showed significant changes during the 3 years after rewetting. We assume that the restored hydrology was not the main factor controlling CH4 emissions and other factors such as vegetation composition and input of available substrate for methanogenic community were more important. Therefore it appears that the period necessary for regeneration of CH4 emissions is the result of restoring all of these elementary factors together.