Towards a Full Accounting of the Greenhouse Gas Balance of European Grasslands

Pastures and livestock production systems are extremely diverse. They occur in a large range of climate and soil conditions and range from very extensive pastoral systems, where domestic herbivores graze and browse rangelands, to intensive systems based on forage and grain crops, where animals are mostly kept indoors. On a global scale, livestock use 3.4 billion ha of grazing land, in addition to animal feed produced on about a quarter of the land under crops (Delgado 2005). Grasslands and pastures contribute to the livelihoods of over 800 million people including many poor smallholders (Reynolds et al. 2005). By 2020, this agricultural sub-sector will produce about 30% of the value of global agricultural output (Delgado 2005). Pastures include both grasslands and rangelands. Grasslands are the natural climax vegetation in areas (e.g. the Steppes of central Asia and the prairies of North America) where the rainfall is low enough to prevent the growth of forests. In other areas, where rainfall is normally higher, grasslands do not form the climax vegetation (e.g. north-western and central Europe) and are more productive. Rangelands are characterised by low stature vegetation, due to temperature and moisture restrictions, and found on every continent. Worldwide the soil organic C sequestration potential is estimated to be 0.01–0.3 GtC year on 3.7 billion ha of permanent pasture (Lal 2004). Thus, soil organic C sequestration by the world’s permanent pastures could potentially offset up to 4% of the global greenhouse gas (GHG) emissions. According to remote sensing data (CORINE LandCover and PELCOM; CORINE 1995, 2000), grasslands cover 20% of the area of the European continent and distribute about equally between western Europe (80 Mha) and eastern Europe (60 Mha). Within the area managed by agricultural practices on the European continent, 37% is devoted to grasslands (EEA 2005). Following the new membership of twelve countries, the EU 27 has an enlarged area of grassland of about 20 million ha (Carlier et al. 2004). The GHG budget of European grasslands is still highly uncertain. There are only few continental scale modelling estimates of the GHG budget of grasslands, primarily