Article

Ecosystems

, Volume 11, Issue 8, pp 1338-1351

Biotic, Abiotic, and Management Controls on the Net Ecosystem CO2 Exchange of European Mountain Grassland Ecosystems

  • Georg WohlfahrtAffiliated withUniversität Innsbruck, Institut für Ökologie Email author 
  • , Margaret Anderson-DunnAffiliated withCentre for Ecology and Hydrology
  • , Michael BahnAffiliated withUniversität Innsbruck, Institut für Ökologie
  • , Manuela BalzaroloAffiliated withDepartment of Forest Environment and Resources, University of Tuscia
  • , Frank BerningerAffiliated withDepartment of Forest Ecology, University of HelsinkiDepartment of Biological Science, University of Quebec at Montreal
  • , Claire CampbellAffiliated withCentre for Ecology and Hydrology
  • , Arnaud CarraraAffiliated withFundacion CEAM
  • , Alessandro CescattiAffiliated withCentro di Ecologia Alpina, Viote del Monte BondoneEuropean Commission—DG Joint Research Centre, Institute for Environment and Sustainability
  • , Torben ChristensenAffiliated withDepartment of Physical Geography and Ecosystems Analysis, Lunds University
    • , Sabina DoreAffiliated withDepartment of Forest Environment and Resources, University of Tuscia
    • , Werner EugsterAffiliated withUniversität Innsbruck, Institut für ÖkologieSwiss Federal Institute of Technology ETH, Institute of Plant Sciences
    • , Thomas FriborgAffiliated withUniversität Innsbruck, Institut für ÖkologieInstitute of Geography, Copenhagen University
    • , Markus FurgerAffiliated withUniversität Innsbruck, Institut für ÖkologieLaboratory of Atmospheric Chemistry, Paul-Scherrer Institute
    • , Damiano GianelleAffiliated withCentro di Ecologia Alpina, Viote del Monte Bondone
    • , Cristina GimenoAffiliated withFundacion CEAM
    • , Ken HargreavesAffiliated withCentre for Ecology and Hydrology
    • , Pertti HariAffiliated withDepartment of Forest Ecology, University of Helsinki
    • , Alois HaslwanterAffiliated withUniversität Innsbruck, Institut für Ökologie
    • , Torbjörn JohanssonAffiliated withDepartment of Physical Geography and Ecosystems Analysis, Lunds University
    • , Barbara MarcollaAffiliated withCentro di Ecologia Alpina, Viote del Monte Bondone
    • , Celia MilfordAffiliated withCentre for Ecology and Hydrology
    • , Zoltan NagyAffiliated withUniversität Innsbruck, Institut für ÖkologieDepartment of Botany and Plant Physiology, Szent István University
    • , Eiko NemitzAffiliated withCentre for Ecology and Hydrology
    • , Nele RogiersAffiliated withUniversität Innsbruck, Institut für ÖkologieLaboratory of Atmospheric Chemistry, Paul-Scherrer InstituteInstitute of Geography, University of Bern
    • , Maria J. SanzAffiliated withFundacion CEAM
    • , Rolf T.W. SiegwolfAffiliated withUniversität Innsbruck, Institut für ÖkologieLaboratory of Atmospheric Chemistry, Paul-Scherrer Institute
    • , Sanna SusiluotoAffiliated withDepartment of Forest Ecology, University of Helsinki
    • , Mark SuttonAffiliated withCentre for Ecology and Hydrology
    • , Zoltan TubaAffiliated withUniversität Innsbruck, Institut für ÖkologieDepartment of Botany and Plant Physiology, Szent István University
    • , Francesca UgoliniAffiliated withCentre for Ecology and Hydrology
    • , Riccardo ValentiniAffiliated withDepartment of Forest Environment and Resources, University of Tuscia
    • , Roberto ZorerAffiliated withUniversität Innsbruck, Institut für ÖkologieIstituto Agrario di S. Michele all’Adige
    • , Alexander CernuscaAffiliated withUniversität Innsbruck, Institut für Ökologie

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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.

Key words

biomass Carbomont ecosystem respiration eddy covariance green area index grazing light response mowing