Theor. Appl. Climatol. 80, 187–203 (2005) DOI 10.1007/s00704-004-0099-7 1 Paul Scherrer Institute, Villigen, Switzerland 2 University of Bern, Institute of Geography, Bern, Switzerland 3 Swiss Federal Institute of Technology, Institute of Plant Sciences, Z€ urich, Switzerland Effect of land management on ecosystem carbon fluxes at a subalpine grassland site in the Swiss Alps N. Rogiers 1 , W. Eugster 2;3 , M. Furger 1 , and R. Siegwolf 1 With 9 Figures Received October 27, 2003; accepted July 20, 2004 Published online November 17, 2004 # Springer-Verlag 2004 Summary The influence of agricultural management on the CO 2 budget of a typical subalpine grassland was investigated at the Swiss CARBOMONT site at Rigi-Seebodenalp (1025 m a.s.l.) in Central Switzerland. Eddy covariance flux measurements obtained during the first growing season from the mid of spring until the first snow fall (17 Mai to 25 September 2002) are reported. With respect to the 10-year average 1992–2001, we found that this growing season had started 10 days earlier than normal, but was close to average tem- perature with above-normal precipitation (100–255% de- pending on month). Using a footprint model we found that a simple approach using wind direction sectors was adequate to classify our CO 2 fluxes as being controlled by either mea- dow or pasture. Two significantly different light response curves could be determined: one for periods with external interventions (grass cutting, cattle grazing) and the other for periods without external interventions. Other than this, mea- dow and pasture were similar, with a net carbon gain of 128  17g Cm 2 on the undisturbed meadow, and a net carbon loss of 79  17 g C m 2 on the managed meadow, and 270  24gCm 2 on the pasture during 131 days of the grow- ing season, respectively. The grass cut in June reduced the gross CO 2 uptake of the meadow by 50  2% until regrowth of the vegetation. Cattle grazing reduced gross uptake over the whole vegetation period (37  2%), but left respiration at a similar level as observed in the meadow. 1. Introduction Ecosystem carbon sequestration is a climate change mitigation strategy based on the assump- tion that the flux of carbon from the air to an eco- system can be increased while the release of carbon from the ecosystem back to the atmosphere can be decreased by choosing an appropriate land management strategy. This transformation has the potential to reduce atmospheric concentrations of carbon dioxide (CO 2 ), thereby slowing global warming and mitigating climate change (Batjes, 1999). The Kyoto Protocol establishes the concept of credits for C sinks (IPCC, 2000). It is possible to take carbon sinks into account to a certain extent in calculating national greenhouse gas balances. It is therefore important to have reliable quantitative information on current carbon stocks and poten- tial sinks (Rosenberger and Izauralde, 2001). Baldocchi et al. (1996) emphasized the need for regional networks of flux measurement sta- tions covering a broad spectrum of ecosystems and climatic conditions. Much effort has been put into quantifying these fluxes over forest eco- systems (Aubinet et al., 2000; Houghton, 1996), but not so for other important vegetation types. Here we report on CO 2 exchange of a mountain- ous pastoral grassland ecosystem in Switzerland that we investigated as part of the Europe- an Union’s 5th Framework Program project CARBOMONT.