Analyzing the major drivers of NEE in a Mediterranean alpine shrubland Reverter, B. R. Pérez Sánchez-Cañete, Enrique Resco, V. Serrano Ortiz, Penélope Oyonarte, C. Kowalski, Andrew Carbon-dioxide exchange Ecosystem CO2 exchange Path Eddy covariance Water vapor Gas analyzers Energy Plants Two years of continuous measurements of net ecosystem exchange (NEE) using the eddy covariance technique were made over a Mediterranean alpine shrubland. This ecosystem was found to be a net source of CO2 (+ 52 ± 7 g C m−2 and + 48 ± 7 g C m−2 for 2007 and 2008) during the two-year study period. To understand the reasons underlying this net release of CO2 into the atmosphere, we analysed the drivers of seasonal variability in NEE over these two years. We observed that the soil water availability – driven by the precipitation pattern – and the photosynthetic photon flux density (PPFD) are the key factors for understanding both the carbon sequestration potential and the duration of the photosynthetic period during the growing season. Finally, the effects of the self-heating correction to CO2 and H2O fluxes measured with the open-path infrared gas analyser were evaluated. Applying the correction turned the annual CO2 budget in 2007 from a sink (− 135 ± 7 g C m−2) to a source (+ 52 ± 7 g C m−2). The magnitude of this change is larger than reported previously and is shown to be due to the low air density and cold temperatures at this high elevation study site. 2014-06-17T08:00:09Z 2014-06-17T08:00:09Z 2010 info:eu-repo/semantics/article Reverter, B.R.; et al. Analyzing the major drivers of NEE in a Mediterranean alpine shrubland. Biogeosciences, 7: 2601-2611 (2010). [http://hdl.handle.net/10481/32274] 1726-4170 1726-4189 http://hdl.handle.net/10481/32274 10.5194/bg-7-2601-2010 eng info:eu-repo/semantics/openAccess Copernicus Publications; European Geosciences Union (EGU)