Importance of methane and nitrous oxide for Europe's terrestrial greenhouse-gas balance

Abstract

Climate change negotiations aim to reduce net greenhouse-gas emissions by encouraging direct reductions of emissions and crediting countries for their terrestrial greenhouse-gas sinks. Ecosystem carbon dioxide uptake has offset nearly 10% of Europe's fossil fuel emissions, but not all of this may be creditable under the rules of the Kyoto Protocol. Although this treaty recognizes the importance of methane and nitrous oxide emissions, scientific research has largely focused on carbon dioxide. Here we review recent estimates of European carbon dioxide, methane and nitrous oxide fluxes between 2000 and 2005, using both top-down estimates based on atmospheric observations and bottom-up estimates derived from ground-based measurements. Both methods yield similar fluxes of greenhouse gases, suggesting that methane emissions from feedstock and nitrous oxide emissions from arable agriculture are fully compensated for by the carbon dioxide sink provided by forests and grasslands. As ! a result, the balance for all greenhouse gases across Europe's terrestrial biosphere is near neutral, despite carbon sequestration in forests and grasslands. The trend towards more intensive agriculture and logging is likely to make Europe's land surface a significant source of greenhouse gases. The development of land management policies which aim to reduce greenhouse-gas emissions should be a priority

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

“…The fractions of OM derived from peat and recent inputs and their decomposability in drained organic soils may, however, sub-stantially vary with land use, site conditions and time since land use conversion. Schulze et al (2009) reported that inputs of fresh organic matter residues were smaller in croplands than in grasslands or forests, suggesting that SOM might be on average more aged and thus less decomposable. In situ measurements of CO 2 fluxes from managed organic soils reveal slower decomposition of peat under forest (IPCC, 2014).…”

Evaluation of cropland maximum light use efficiency using eddy flux measurements in North America and Europe

“…Regionally, this fraction can increase to 33% in Europe and 20% in the United States [Ramankutty et al, 2008]. Schulze et al [2009] suggested that croplands are a net source of greenhouse gasses to the atmosphere in Europe. In contrast, croplands were identified as a sink in the United States [West et al, 2010].…”

Recent advances and future directions in soils and sediments research

“…Significantly, more C is stored in the world's soils than in the above-ground biomass and atmosphere (Davidson and Janssens 2006;Fontaine et al 2007;Gruber and Galloway 2008;Heimann and Reichstein 2008;Piao et al 2009). Soil C dynamics and N cycling are closely linked, important biogeochemical processes underpinning the positive feedbacks between terrestrial ecosystems and global warming (Davidson and Janssens 2006;Gruber and Galloway 2008;Heimann and Reichstein 2008;Schulze et al 2009;Xu et al 2009). In the past decade, there have been significant and exciting developments in testing and applying advanced chemical and bio-molecular techniques for unravelling soil C and N cycling processes in terrestrial ecosystems, such as those of stable isotope methods (Blumfield et al 2004;Bengtson and Bengtsson 2007;Burton et al 2007;Strand et al 2008;Xu et al 2009), nuclear magnetic resonance (NMR) spectroscopy (Mathers et al 2000;Mao et al 2002;Chen et al 2004;Fontaine et al 2007;Xu et al 2009), and bio-molecular approaches (He et al 2005(He et al , 2006(He et al , 2007Bastias et al 2007;Di et al 2009).…”

“…Recent literature reviews on greenhouse gas emissions (Liu and Greaver 2009;Schulze et al 2009) and terrestrial C and N cycles (Gruber and Galloway 2008;Heimann and Reichstein 2008;Xu et al 2009) have highlighted that soil microbial populations (Mitchell et al 2009) play a central role in regulating the major greenhouse emissions of CO 2 (Bond-Lamberty et al 2007;Arnone et al 2008;Bowman et al 2009;Dorrepaal et al 2009), methane (CH 4 ) (Raghoebarsing et al 2006;Dunfield et al 2007;Kennedy et al 2008;Megonigal and Guenther 2008), and nitrous oxide (N 2 O) (Horz et al 2004;Leininger et al 2006;Di et al 2009;Erguder et al 2009;Martens-Habbena et al 2009), particularly in the context of climate change and management options for reducing greenhouse gas emissions (Di et al 2009;Ravishankara et al 2009;Schulze et al 2009) and increasing C sequestration in terrestrial ecosystems (Magnani et al 2007;Houlton et al 2008;Lewis et al 2009;Reich 2009;Rotenberg and Yakir 2010). Labile soil C and N pools and dynamics are more sensitive to climate change (Davidson and Janssens 2006;Fontaine et al 2007;Arnone et al 2008;Trumbore and Czimczic 2008;Dorrepaal et al 2009) and management regimes (Mao et al 2002;Magnani et al 2007;Di et al 2009), and closely linked to the greenhouse gas emissions …”