Inventory and eddy covariance-based estimates of annual carbon sequestration in a Sitka spruce (Picea sitchensis (Bong.) Carr.) forest ecosystem
2007
Black, K. | Bolger, T. | Davis, P. | Nieuwenhuis, M. | Reidy, B. | Saiz, G. | Tobin, B. | Osborne, B.
A comparison was made of annual net ecosystem productivity (NEP) of a closed canopy Sitka spruce forest over 2 years, using either eddy covariance or inventory techniques. Estimates for annual net uptake of carbon (C) by the forest varied between 7.30 and 11.44 t C ha⁻¹ year⁻¹ using ecological inventory (NEPₑcₒ) measures and 7.69–9.44 t C ha⁻¹ year⁻¹ using eddy covariance-based NEP (-NEE) assessments. These differences were not significant due to uncertainties and errors associated with estimates of biomass increment (15–21%) and heterotrophic respiration (12–19%). Carbon-stock change inventory (NEPΔC) values were significantly higher (27–32%), when compared to both NEPₑcₒ- and -NEE-based estimates. Additional analyses of the data obtained from this study, together with published data, suggest that there was a systematic overestimation of NEPΔC -based assessments due to unaccounted decomposition processes and uncertainties in the estimation of soil-C stock changes. In contrast, there was no systematic difference between NEPₑcₒ and eddy covariance assessments across a wide range of forest types and geographical locations.
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