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Abstract. Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep-grazed drained moorland and intensively sheep-grazed fertilised grassland in South East (SE) Scotland were compared over 4 yr (2007–2010). Nitrous oxide (N2O) and methane (CH4) fluxes were measured by static chambers, respiration from soil plus ground vegetation by a flow-through chamber, and the net ecosystem exchange (NEE) of carbon dioxide (CO2) by eddy-covariance. All GHG fluxes displayed high temporal and interannual variability. Temperature, radiation, water table height and precipitation could explain a significant percentage of seasonal and interannual variations. Greenhouse gas fluxes were dominated by the net ecosystem exchange of CO2 at both sites. Net ecosystem exchange of CO2 and respiration was much larger on the productive fertilised grassland (−1567 and 7157 g CO2eq m−2 yr−1, respectively) than on the seminatural moorland (−267 and 2554 g CO2eq m−2 yr−1, respectively). Large ruminant CH4 (147 g CO2eq m−2 yr−1) and soil N2O (384 g CO2eq m−2 yr−1) losses from the grazed grassland counteracted the CO2 uptake by 34%, whereas the small N2O (0.8 g CO2eq m−2 yr−1) and CH4 (7 g CO2eq m−2 yr−1) emissions from the moorland only impacted the NEE flux by 3%. The 4-yr average GHG budget for the grazed grassland was −1034 g CO2eq m−2 yr−1 and −260 g CO2eq m−2 yr−1 for the moorland.

Abstract. Land–atmosphere exchange of carbon dioxide (CO2) in peatlands exhibits marked seasonal and inter-annual variability, which subsequently affects the carbon (C) sink strength of catchments across multiple temporal scales. Long-term studies are needed to fully capture the natural variability and therefore identify the key hydrometeorological drivers in the net ecosystem exchange (NEE) of CO2. Since 2002, NEE has been measured continuously by eddy-covariance at Auchencorth Moss, a temperate lowland peatland in central Scotland. Hence this is one of the longest peatland NEE studies to date. For 11 years, the site was a consistent, yet variable, atmospheric CO2 sink ranging from −5.2 to −135.9 g CO2-C m−2 yr−1 (mean of −64.1 ± 33.6 g CO2-C m−2 yr−1). Inter-annual variability in NEE was positively correlated to the length of the growing season. Mean winter air temperature explained 87% of the inter-annual variability in the sink strength of the following summer, indicating an effect of winter climate on local phenology. Ecosystem respiration (Reco) was enhanced by drought, which also depressed gross primary productivity (GPP). The CO2 uptake rate during the growing season was comparable to three other sites with long-term NEE records; however, the emission rate during the dormant season was significantly higher. To summarise, the NEE of the peatland studied is modulated by two dominant factors: - phenology of the plant community, which is driven by winter air temperature and impacts photosynthetic potential and net CO2 uptake during the growing season (colder winters are linked to lower summer NEE), - water table level, which enhanced soil respiration and decreased GPP during dry spells. Although summer dry spells were sporadic during the study period, the positive effects of the current climatic trend towards milder winters on the site's CO2 sink strength could be offset by changes in precipitation patterns especially during the growing season.

Abstract. Land–atmosphere exchange of carbon dioxide (CO2) in peatlands exhibits marked seasonal and inter-annual variability, which subsequently affects the carbon sink strength of catchments across multiple temporal scales. Long-term studies are needed to fully capture the natural variability and therefore identify the key hydrometeorological drivers in the net ecosystem exchange (NEE) of CO2. NEE has been measured continuously by eddy-covariance at Auchencorth Moss, a temperate lowland peatland in central Scotland, since 2002. Hence this is one of the longest peatland NEE studies to date. For 11 yr, the site was a consistent, yet variable, atmospheric CO2 sink ranging from −5.2 to −135.9 g CO2-C m−2 yr−1 (mean of −64.1 ± 33.6 g CO2-C m−2 yr−1). Inter-annual variability in NEE was positively correlated to the length of the growing season. Mean winter air temperature explained 87% of the inter-annual variability in the sink strength of the following summer, indicating a phenological memory-effect. Plant productivity exhibited a marked hysteresis with respect to photosynthetically active radiation (PAR) over the growing season, indicative of two separate growth regimes. Ecosystem respiration (Reco) and gross primary productivity (GPP) were closely correlated (ratio 0.74), suggesting that autotrophic processes were dominant. Whilst the site was wet most of the year (water table depth <5 cm) there were indications that heterotrophic respiration was enhanced by drought, which also depressed GPP. NEE was compared to 5 other peatland sites which have published long-term NEE records. The CO2 uptake rate during the growing season was comparable to 3 other European sites, however the emission rate during the dormant season was significantly higher.

Greenhouse gas (GHG) fluxes from a seminatural, extensively sheep grazed drained moorland and intensively sheep grazed fertilised grassland in SE Scotland were compared over 4 yr (2007–2010). Nitrous oxide and CH₄ fluxes were measured by static chambers, respiration from soil including ground vegetation by a flow through chamber and the net ecosystem exchange of CO₂ by eddy covariance. All GHG fluxes displayed high temporal and interannual variability. Temperature, radiation, water table height and precipitation could explain a significant percentage of seasonal and interannual variations. Greenhouse gas fluxes were dominated by the net ecosystem exchange of CO₂, emissions of N₂O from the grazed grassland (384 g CO_2eq m^&minus;2 yr^&minus;1) and emissions of CH₄ from ruminant fermentation (147 g CO_2eq m^&minus;2 yr^&minus;1). Methane emissions from the moorland were small (6.7 g CO_2eq m^&minus;2 yr^&minus;1). Net ecosystem exchange of CO₂ and respiration were much larger on the productive fertilised grassland (−1624 and +7157 g CO_2eq m^&minus;2 yr^&minus;1, respectively) than the seminatural moorland (−338 and +2554 g CO_2eq m^&minus;2 yr^&minus;1, respectively). Large CH₄ and N₂O losses from the grazed grassland counteracted the CO₂ uptake by 35%, whereas the small N₂O and CH₄ emissions from the moorland did only impact the NEE by 2%.The 4 yr average GHG budget for the grazed grassland was 1006 g CO_2eq m^&minus;2 yr^&minus;1 and 331 g CO_2eq m^&minus;2 yr^&minus;1 for the moorland