CR 14:57-63 (2000)  -  doi:10.3354/cr014057

ABSTRACT: Eddy correlation measurements of CO₂ exchange were made in intensively managed peat pastures at 2 different groundwater tables during most of a growing season. F was separated into a respiratory and an assimilatory CO₂ flux. The fit of the Arrhenius temperature response to F_r showed that F_r was generally higher at low groundwater tables. The fit of a hyperbolic irradiance response to F_a showed that F_a was also generally higher at low groundwater tables, more than compensating for higher F_r. The daily CO₂ balance suggested that the low groundwater pasture was a larger CO₂ sink or a smaller CO₂ source than the high groundwater pasture during the measurement period. The difference in F_r between the groundwater tables was substantially less than the factor 2 difference in level of soil subsidence. This suggests that oxidization of soil organic matter was a relatively minor factor in soil subsidence.

KEY WORDS: Eddy correlation · CO₂ exchange · Assimilatory flux · Respiratory flux · Pasture · Grassland · Peat · Drainage