A Preliminary intercomparison of micrometeorological and ecological estimates of carbon sequestration in a Mid-latitude Deciduous Forest for 1998 and 1999

The role of mid-latitude forests in the sequestration of carbon (C) is subject to some debate. Net CO2 exchange on an annual basis can be measured using eddy covariance techniques or from ecological inventories of various C compartments. Here we present an inter-comparison of two annual (1998, 1999) estimates of C sequestration in a mixed hardwood forest in the Morgan-Monroe State Forest, Indiana, USA. Eddy covariance estimates were made at 46 m (1.8 times canopy height). For the same time period, ecological measures and model estimates of change in living biomass, sum of above-ground and below-ground detritus production, consumption, and forest floor and soil respiration were made. In 1998, based on eddy covariance measurements, C sequestration was 237 g C m-2 a-1, from ecological inventory methods 263.8 g C m-2 a-1, a difference of ~10%.

The ecological inventory estimate is quite consistent with the eddy-covariance CO2 flux estimate, and can be considered an independent validation. Although these benchmark CO2 flux values are from a single site from a single year, the spatial and temporal representatitiveness of the sampling period and site, allow these results to be viewed as additional evidence that mid-latitude forests of the northern hemisphere serve as a large sink in the global carbon cycle.