Synthesizing greenhouse gas fluxes across nine European peatlands and shrublands – responses to climatic and environmental changes
- 1Centre for Ecosystems and Environmental Sustainability, Department of Chemical and Biochemical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
- 2Centre for Ecology & Hydrology, Environment Centre Wales, Deiniol Rd, Bangor, Gwynedd, LL57 2UW, UK
- 3CREAF, Cerdanyola del Vallés 08193, Catalonia, Spain
- 4CSIC, Global Ecology Unit CREAF-CEAB-UAB, Cerdanyola del Vallés 08913, Catalonia, Spain
- 5School of Science and the Environment, Manchester Metropolitan University, Chester Street, Manchester, M1 5GD, UK
- 6Centre for Ecology & Hydrology, Edinburgh, Bush Estate, Penicuik, Midlothian, EH26 0QB, UK
- 7Department of Earth and Ecosystem Sciences, Lund University, Sölvegatan 12, 22362 Lund, Sweden
- 8Department of Bioscience, Aarhus University, Frederiksborgvej 399, P.O. Box 358, 4000 Roskilde, Denmark
- 9European Commission – DG Joint Research Centre, Institute for Environment and Sustainability, Climate Change and Air Quality Unit, Via Enrico Fermi 2749 I21027 Ispra (VA), Italy
- 10Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1, Tartu 51014, Estonia
- 11Department of Geoscience, Natural Resources and Planning, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg, Denmark
- 12Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands
- *now at: Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Ecological Systems, Station 2, 1015 Lausanne, Switzerland
Abstract. In this study, we compare annual fluxes of methane (CH4), nitrous oxide (N2O) and soil respiratory carbon dioxide (CO2) measured at nine European peatlands (n = 4) and shrublands (n = 5). The sites range from northern Sweden to Spain, covering a span in mean annual air temperature from 0 to 16 °C, and in annual precipitation from 300 to 1300 mm yr−1. The effects of climate change, including temperature increase and prolonged drought, were tested at five shrubland sites. At one peatland site, the long-term (> 30 yr) effect of drainage was assessed, while increased nitrogen deposition was investigated at three peatland sites.
The shrublands were generally sinks for atmospheric CH4, whereas the peatlands were CH4 sources, with fluxes ranging from −519 to +6890 mg CH4-C m−2 yr−1 across the studied ecosystems. At the peatland sites, annual CH4 emission increased with mean annual air temperature, while a negative relationship was found between net CH4 uptake and the soil carbon stock at the shrubland sites. Annual N2O fluxes were generally small ranging from −14 to 42 mg N2O-N m−2 yr−1. Highest N2O emission occurred at the sites that had highest nitrate (NO3−) concentration in the soil water. Furthermore, experimentally increased NO3− deposition led to increased N2O efflux, whereas prolonged drought and long-term drainage reduced the N2O efflux. Soil CO2 emissions in control plots ranged from 310 to 732 g CO2-C m−2 yr−1. Drought and long-term drainage generally reduced the soil CO2 efflux, except at a hydric shrubland where drought tended to increase soil respiration.
In terms of fractional importance of each greenhouse gas to the total numerical global warming response, the change in CO2 efflux dominated the response in all treatments (ranging 71–96%), except for NO3− addition where 89% was due to change in CH4 emissions. Thus, in European peatlands and shrublands the effect on global warming induced by the investigated anthropogenic disturbances will be dominated by variations in soil CO2 fluxes.