Comparison of soil greenhouse gas fluxes from extensive and intensive grazing in a temperate maritime climate

[摘要] Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep-grazeddrained moorland and intensively sheep-grazed fertilised grassland inSouth East (SE) Scotland were compared over 4 yr (2007–2010). Nitrousoxide (N₂O) and methane (CH₄) fluxes were measured by staticchambers, respiration from soil plus ground vegetation by a flow-throughchamber, and the net ecosystem exchange (NEE) of carbon dioxide (CO₂)by eddy-covariance. All GHG fluxes displayed high temporal and interannualvariability. Temperature, radiation, water table height and precipitationcould explain a significant percentage of seasonal and interannualvariations. Greenhouse gas fluxes were dominated by the net ecosystemexchange of CO₂ at both sites. Net ecosystem exchange of CO₂ andrespiration was much larger on the productive fertilised grassland (−1567and 7157 g CO_2eq m⁻² yr⁻¹, respectively) than on the seminaturalmoorland (−267 and 2554 g CO_2eq m⁻² yr⁻¹, respectively). Largeruminant CH₄ (147 g CO_2eq m⁻² yr⁻¹) and soil N₂O(384 g CO_2eq m⁻² yr⁻¹) losses from the grazed grasslandcounteracted the CO₂ uptake by 34%, whereas the small N₂O (0.8 g CO_2eq m⁻² yr⁻¹) and CH₄(7 g CO_2eq m⁻² yr⁻¹) emissions from the moorland only impacted the NEE flux by3%. The 4-yr average GHG budget for the grazed grassland was −1034 g CO_2eq m⁻² yr⁻¹ and −260 g CO_2eq m⁻² yr⁻¹ forthe moorland.

[学科分类] 地球化学与岩石