Synthesizing greenhouse gas fluxes across nine European peatlands and shrublands – responses to climatic and environmental changes

[摘要] In this study, we compare annual fluxes of methane (CH₄), nitrous oxide(N₂O) and soil respiratory carbon dioxide (CO₂) measured at nineEuropean peatlands (n = 4) and shrublands (n = 5). The sites range fromnorthern Sweden to Spain, covering a span in mean annual air temperature from0 to 16 °C, and in annual precipitation from 300 to1300 mm yr⁻¹. The effects of climate change, including temperatureincrease and prolonged drought, were tested at five shrubland sites. At onepeatland 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 thepeatlands were CH₄ sources, with fluxes ranging from −519 to+6890 mg CH₄-C m⁻² yr⁻¹ across the studied ecosystems. Atthe peatland sites, annual CH₄ emission increased with mean annual airtemperature, while a negative relationship was found between net CH₄uptake and the soil carbon stock at the shrubland sites. Annual N₂Ofluxes were generally small ranging from −14 to42 mg N₂O-N m⁻² yr⁻¹. Highest N₂O emission occurredat the sites that had highest nitrate (NO₃⁻) concentration in thesoil water. Furthermore, experimentally increased NO₃⁻ deposition ledto increased N₂O efflux, whereas prolonged drought and long-termdrainage reduced the N₂O efflux. Soil CO₂ emissions in controlplots ranged from 310 to 732 g CO₂-C m⁻² yr⁻¹. Drought andlong-term drainage generally reduced the soil CO₂ efflux, except at ahydric shrubland where drought tended to increase soil respiration.

In terms of fractional importance of each greenhouse gas to the totalnumerical global warming response, the change in CO₂ efflux dominatedthe response in all treatments (ranging 71–96%), except forNO₃⁻ addition where 89% was due to change in CH₄ emissions.Thus, in European peatlands and shrublands the effect on global warminginduced by the investigated anthropogenic disturbances will be dominated byvariations in soil CO₂ fluxes.

[学科分类] 地球化学与岩石