Surface CO2 exchange in an intensively managed peat pasture

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).