Biotic, Abiotic, and Management Controls on the Net Ecosystem CO2 Exchange of European Mountain Grassland Ecosystems |
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Authors: | Georg Wohlfahrt Margaret Anderson-Dunn Michael Bahn Manuela Balzarolo Frank Berninger Claire Campbell Arnaud Carrara Alessandro Cescatti Torben Christensen Sabina Dore Werner Eugster Thomas Friborg Markus Furger Damiano Gianelle Cristina Gimeno Ken Hargreaves Pertti Hari Alois Haslwanter Torbjörn Johansson Barbara Marcolla Celia Milford Zoltan Nagy Eiko Nemitz Nele Rogiers Maria J Sanz Rolf TW Siegwolf Sanna Susiluoto Mark Sutton Zoltan Tuba Francesca Ugolini Riccardo Valentini Roberto Zorer Alexander Cernusca |
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Institution: | 1. Universit?t Innsbruck, Institut für ?kologie, Sternwartestr. 15, 6020, Innsbruck, Austria 2. Centre for Ecology and Hydrology, Bush Estate, EH260QB, Penicuik, United Kingdom 3. Department of Forest Environment and Resources, University of Tuscia, Via S.C. de Lellis, 01100, Viterbo, Italy 4. Department of Forest Ecology, University of Helsinki, Viikinkari 7, P.O. Box 27, 00014, Helsinki, Finland 5. Department of Biological Science, University of Quebec at Montreal, P.O. Box 8888, Montreal, Quebec, Canada, H3C?3P8 6. Fundacion CEAM, c/Charles Darwin 14, Parque Tecnológico, 46980, Paterna, Spain 7. Centro di Ecologia Alpina, Viote del Monte Bondone, 38040, Trento, Italy 8. European Commission—DG Joint Research Centre, Institute for Environment and Sustainability, 21020, Ispra, Italy 9. Department of Physical Geography and Ecosystems Analysis, Lunds University, S?lvegatan 12, 223 62, Lund, Sweden 10. Swiss Federal Institute of Technology ETH, Institute of Plant Sciences, Universit?tsstr 2, 8092, Zürich, Switzerland 11. Institute of Geography, Copenhagen University, ?ster Voldgade 10, 1350, Copenhagen, Denmark 12. Laboratory of Atmospheric Chemistry, Paul-Scherrer Institute, 5232, Villigen, Switzerland 13. Department of Botany and Plant Physiology, Szent István University, Páter Károly u. 1, 2103, Godollo, Hungary 14. Institute of Geography, University of Bern, Hallerstr 12, 3012, Bern, Switzerland 15. Istituto Agrario di S. Michele all’Adige, Via Edmondo Mach 1, 38010 S, Michele all’Adige, Italy
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Abstract: | The net ecosystem carbon dioxide (CO2) exchange (NEE) of nine European mountain grassland ecosystems was measured during 2002–2004 using the eddy covariance method.
Overall, the availability of photosynthetically active radiation (PPFD) was the single most important abiotic influence factor
for NEE. Its role changed markedly during the course of the season, PPFD being a better predictor for NEE during periods favorable
for CO2 uptake, which was spring and autumn for the sites characterized by summer droughts (southern sites) and (peak) summer for
the Alpine and northern study sites. This general pattern was interrupted by grassland management practices, that is, mowing
and grazing, when the variability in NEE explained by PPFD decreased in concert with the amount of aboveground biomass (BMag). Temperature was the abiotic influence factor that explained most of the variability in ecosystem respiration at the Alpine
and northern study sites, but not at the southern sites characterized by a pronounced summer drought, where soil water availability
and the amount of aboveground biomass were more or equally important. The amount of assimilating plant area was the single
most important biotic variable determining the maximum ecosystem carbon uptake potential, that is, the NEE at saturating PPFD.
Good correspondence, in terms of the magnitude of NEE, was observed with many (semi-) natural grasslands around the world,
but not with grasslands sown on fertile soils in lowland locations, which exhibited higher maximum carbon gains at lower respiratory
costs. It is concluded that, through triggering rapid changes in the amount and area of the aboveground plant matter, the
timing and frequency of land management practices is crucial for the short-term sensitivity of the NEE of the investigated
mountain grassland ecosystems to climatic drivers. |
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Keywords: | biomass Carbomont ecosystem respiration eddy covariance green area index grazing light response mowing |
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