Effects of Land-Use Changes on Sources, Sinks and Fluxes of Carbon in European Mountain Grasslands

Abstract

Mountain regions are important sources of water(Mountain Agenda 1998), centers of biodiversity(Ko¨rner and Spehn 2002) and areas for recreationand tourism, but they are also highly sensitive tohuman (Cernusca and others 1999) and climateeffects (Beniston 1994). Ongoing socio-economicchanges have strongly influenced land use inmountain areas, resulting in patterns of intensifi-cation and abandonment that differ across Europe(Tappeiner and others 2003). During the last dec-ade there have been considerable efforts to assessthe contribution of different ecosystems to theglobal carbon cycle (Baldocchi 2008). There is al-ready substantial information on the carbonsequestration of forest ecosystems (Valentini andothers 2000); however, data on the carbon cyclingof non-forest ecosystems are still underrepresented(Falge and others 2002). Grasslands cover about40% of the global terrestrial ice-free surface, buttheir contribution to local and regional carbonfluxes remains uncertain (but see Gilmanov andothers 2007; Sousanna and others 2007). Further-more, there are no studies that address the carbonbalances of European semi-natural grasslands, asmost of the mountain grasslands are, but studieshave focussed on more intensively managed culti-vated grasslands or semi-arid grassland areas. Thestudies carried out so far suggest that grasslands canbe either a sink or a source of carbon (Novick andothers 2004; Gilmanov and others 2007). Thecauses for the observed variability, in particularinter-active effects of climate and land use on thegrassland CO