Greenhouse Gas Exchange of a NW German Peatland, 18 Years After Rewetting

Abstract

Peatlands cover only 3% of the Earth's land surface, but they store about 25% of the global carbon (C) pool (Leifeld & Menichetti, 2018;Page & Baird, 2016). They play a major role in the global biogeochemical cycles (Gorham, 1991) and the Earth's climate system, because they act as sources and sinks of greenhouse gases (GHG) such as carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). Undisturbed, growing peatlands under natural conditions usually act as long-term C and GHG sinks, that is, following the first centuries to thousands years after initiation, the cooling effect of CO 2 sequestration outweighs the warming effect of short-lived CH 4 emissions (Frolking & Roulet, 2007;Mathijssen et al., 2017). In Europe, including the European part of Russia, still a fraction of 54% of the peatlands are undisturbed. Focusing on Germany, the fraction of peatlands that still accumulate peat (mires) is only ∼2% (Joosten et al., 2017;Tanneberger et al., 2017). The high percentage of degraded peatlands in Germany and other aeras of western Europe puts these ecosystems into the focus of global climate research. When peatlands are drained, this leads to peat oxidation and mineralization and turns peatland ecosystems from a net sink to a net source of GHG (

Variation in the Mercury Concentrations and Greenhouse Gas Emissions of Pristine and Managed Hemiboreal Peatlands

“…Peatlands provide many important ecosystem services, including water supply regulation and flood risk mitigation, global biodiversity preservation, climate change mitigation and material for energy production and recreation [4]. Peatlands play an important role in the control of atmospheric greenhouse gases (GHGs) such as carbon dioxide (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) and thus affect global climate change [7][8][9]. The dynamics of C balance and GHG flux in peatlands depend greatly on peatland hydrology [3].…”

“…The dynamics of C balance and GHG flux in peatlands depend greatly on peatland hydrology [3]. Peatlands usually act as long-term C and GHG sinks [3,[9][10][11]. In the anaerobic Land 2022, 11, 1414 2 of 19 zones of submerged soils, CH 4 is produced by methanogens and substantial quantities of C are emitted as CH 4 in the terminal step of anaerobic organic matter mineralization [3,5,12].…”

Carbon and climate implications of rewetting a raised bog in Ireland

“…Clearly, the shallow flooding of the living vegetation layer prior to drain blocking and subsequent rewetting has proven an issue in terms of CH 4 emissions, with other peatland rewetting studies reporting similar findings following inundation (Hahn‐Schöfl et al, 2011; Huth et al, 2021). While the NECB in the drained area was primarily dominated by the CO 2 component (90%), the contribution of CH 4 was considerably greater in the rewetted area, a feature noted in other peatland rewetting studies (e.g., Schaller et al, 2022; Wilson, Blain, et al, 2016) and modelling exercises (e.g., Tanneberger et al, 2020).…”

Long-term flux measurements suggest dynamic emission factors are needed for rewetted peatlands

“…However, due to large uncertainties, countries are encouraged to develop more detailed and dynamic EFs that fully capture the transient nature of C fluxes in the time since rewetting and at national level (Tier 2). Few peer-review studies have published results of long-term annual C exchange in peatlands, particularly temperate rewetted peatlands with modified water table regimes 9,26,27,28,29 , using the eddy covariance (EC) technique. In view of more frequent extreme events, such long-term collection of in-situ measurements following rewetting is also needed to understand the impact of drought in temperate peatlands 26,30,31,32 .…”