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

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 (g_s) was calculated from the Penman-Monteith equation. F was split into a respiratory CO₂ flux (F_r) and an assimilatory CO₂ flux (F_a). F_r was non-linearly related to air temperature (T_a), revealing a distinct seasonal pattern in its value normalized to T_a. F_a was hyperbolically related to short-wave irradiance, the seasonal pattern of its maximum value compared to that of normalized F_r. T_a proved to be a major factor: F_a tended to maintain a positive response to T_a over much of the actual T_a range. Aerial vapour pressure deficit (D) was generally too low (<1 kPa) to have an effect on F_a.

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