Multiyear greenhouse gas balances at a rewetted temperate peatland.
Drained peat soils are a significant source of greenhouse gas (GHG) emissions to the atmosphere. Rewetting these soils is considered an important climate change mitigation tool to reduce emissions and create suitable conditions for carbon sequestration. Long-term monitoring is essential to capture interannual variations in GHG emissions and associated environmental variables and to reduce the uncertainty linked with GHG emission factor calculations. In this study, we present GHG balances: carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) calculated for a 5-year period at a rewetted industrial cutaway peatland in Ireland (rewetted 7 years prior to the start of the study); and compare the results with an adjacent drained area (2-year data set), and with ten long-term data sets from intact (i.e. undrained) peatlands in temperate and boreal regions. In the rewetted site, CO2exchange (or net ecosystem exchange (NEE)) was strongly influenced by ecosystem respiration (Reco) rather than gross primary production (GPP). CH4emissions were related to soil temperature and either water table level or plant biomass. N2O emissions were not detected in either drained or rewetted sites. Rewetting reduced CO2emissions in unvegetated areas by approximately 50%. When upscaled to the ecosystem level, the emission factors (calculated as 5-year mean of annual balances) for the rewetted site were (±SD) -104 ± 80 g CO2-C m-2yr-1(i.e. CO2sink) and 9 ± 2 g CH4-C m-2yr-1(i.e. CH4source). Nearly a decade after rewetting, the GHG balance (100-year global warming potential) had reduced noticeably (i.e. less warming) in comparison with the drained site but was still higher than comparative intact sites. Our results indicate that rewetted sites may be more sensitive to interannual changes in weather conditions than their more resilient intact counterparts and may switch from an annual CO2sink to a source if triggered by slightly drier conditions.
Earthy Matters Environmental Consultants, Glenvar, Co. Donegal, F92 HX03, Ireland.
David
D
Wilson
Bord na Móna, Tullamore, Co. Offaly, Ireland.
Catherine A
CA
Farrell
Bord na Móna, Tullamore, Co. Offaly, Ireland.
David
D
Fallon
Justus Liebig University Giessen, Ludwigstraße 23, 35390, Giessen, Germany.
Gerald
G
Moser
Justus Liebig University Giessen, Ludwigstraße 23, 35390, Giessen, Germany.|University College Dublin, Belfield, Dublin 4, D04 V1W8, Ireland.
Christoph
C
Müller
University College Dublin, Belfield, Dublin 4, D04 V1W8, Ireland.
Florence
F
Renou-Wilson
D002245:Carbon Dioxide / Q000032:analysis; D057965:Carbon Sequestration; D057231:Climate Change; D005740:Gases / Q000032:analysis*; D017752:Greenhouse Effect; D007494:Ireland; D008697:Methane / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D012987:Soil / Q000737:chemistry; D014867:Water; D053833:Wetlands
D005740:Gases; D012987:Soil; D014867:Water; D002245:Carbon Dioxide; D009609:Nitrous Oxide; D008697:Methane
carbon dioxide; climate change mitigation; interannual variation; methane; peat soils; rewetting