Partitioning European grassland net ecosystem CO2 exchange into gross primary productivity and ecosystem respiration using light response function analysis

T. G. Gilmanov, J. F. Soussana, L. Aires, V. Allard, Christof Ammann, M. Balzarolo, Z. Barcza, C. Bernhofer, C. L. Campbell, A. Cernusca, A. Cescatti, John C. Clifton-Brown, B. O. M. Dirks, S. Dore, W. Eugster, Jurg Fuhrer, C. Gimeno, T. Gruenwald, L. Haszpra, A. HensenA. Ibrom, A. F. G. Jacobs, M. B. Jones, G. Lanigan, T. Laurila, A. Lohila, G. Manca, B. Marcolla, Z. Nagy, K. Pilegaard, K. Pinter, C. Pio, A. Raschi, N. Rogiers, M. J. Sanz, P. Stefani, M. Sutton, Z. Tuba, R. Valentini, M. L. Williams, G. Wohlfahrt

Research output: Contribution to journalArticlepeer-review

287 Citations (SciVal)

Abstract

Tower CO2 flux measurements from 20 European grasslands in the EUROGRASSFLUX data set covering a wide range of environmental and management conditions were analyzed with respect to their ecophysiological characteristics and CO2 exchange (gross primary production, Pg, and ecosystem respiration, Re) using light-response function analysis. Photosynthetically active radiation (Q) and top-soil temperature (Ts) were identified as key factors controlling CO2 exchange between grasslands and the atmosphere at the 30-min scale. A nonrectangular hyperbolic light-response model P(Q) and modified nonrectangular hyperbolic light–temperature-response model P(Q, Ts) proved to be flexible tools for modeling CO2 exchange in the light. At night, it was not possible to establish robust instantaneous relationships between CO2 evolution rate rn and environmental drivers, though under certain conditions, a significant relationship rn=r0 ekTTs was found using observation windows 7–14 days wide. Principal light-response parameters—apparent quantum yield, saturated gross photosynthesis, daytime ecosystem respiration, and gross ecological light-use efficiency, = Pg/Q, display patterns of seasonal dynamics which can be formalized and used for modeling. Maximums of these parameters were found in intensively managed grasslands of Atlantic climate. Extensively used semi-natural grasslands of southern and central Europe have much lower production, respiration, and light-use efficiency, while temperate and mountain grasslands of central Europe ranged between these two extremes. Parameters from light–temperature-response analysis of tower data are in agreement with values obtained using closed chambers and free-air CO2 enrichment. Correlations between light-response and productivity parameters provides the possibility to use the easier to measure parameters to estimate the parameters that are more difficult to measure. Gross primary production (Pg) of European grasslands ranges from 1700 g CO2 m−2 year−1 in dry semi-natural pastures to 6900 g CO2 m−2 year−1 in intensively managed Atlantic grasslands. Ecosystem respiration (Re) is in the range 1800 <Re <6000 g CO2 m−2 year−1. Annual net ecosystem CO2 exchange (NEE) varies from significant net uptake (>2400 g CO2 m−2 year−1) to significant release (
Original languageEnglish
Pages (from-to)93-120
Number of pages27
JournalAgriculture, Ecosystems and Environment
Volume121
Issue number1-2
Early online date22 Jan 2007
DOIs
Publication statusPublished - Jun 2007

Keywords

  • grassland ecosystems
  • eddy covariance-measured CO2 flux
  • net CO2 flux partitioning
  • gross primary production
  • ecosystem respiration
  • nonrectangular hyperbolic model

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