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CR 13:115-123 (1999)  -  doi:10.3354/cr013115

Surface CO2 exchange in an intensively managed peat pasture

B. O. M. Dirks1,*, A. Hensen2, J. Goudriaan1

1Wageningen Agricultural University, Dept of Theoretical Production Ecology, PO Box 430, 6700 AK Wageningen, The Netherlands
2Netherlands Energy Research Foundation, PO Box 1, 1755 ZG Petten, The Netherlands

ABSTRACT: Aerodynamic measurements of CO2 (F) and latent heat (λE) exchange were made in an intensively managed peat pasture during 2 consecutive years; the fetch was approximately 1.5 km. Surface conductance (gs) was calculated from the Penman-Monteith equation. F was split into a respiratory CO2 flux (Fr) and an assimilatory CO2 flux (Fa). Fr was non-linearly related to air temperature (Ta), revealing a distinct seasonal pattern in its value normalized to Ta. Fa was hyperbolically related to short-wave irradiance, the seasonal pattern of its maximum value compared to that of normalized Fr. Ta proved to be a major factor: Fa tended to maintain a positive response to Ta over much of the actual Ta range. Aerial vapour pressure deficit (D) was generally too low (<1 kPa) to have an effect on Fa.

KEY WORDS: Aerodynamic technique · CO2 exchange · Assimilatory flux · Respiratory flux · Surface conductance · Pasture · Grassland

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