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In-situ Observations
Abstract:
The eddy-covariance (EC) micro-meteorological technique and the ecology-based biometric
methods (BM) are the primary methodologies to quantify CO2 exchange between terrestrial
ecosystems and the atmosphere (net ecosystem production, NEP) and its two components,
ecosystem respiration and gross primary production. Here we show that EC and BM provide
different estimates of NEP, but comparable ecosystem respiration and gross primary
production for forest ecosystems globally. Discrepancies between methods are not related to
environmental or stand variables, but are consistently more pronounced for boreal forests
where carbon fluxes are smaller. BM estimates are prone to underestimation of net primary
production and overestimation of leaf respiration. EC biases are not apparent across sites,
suggesting the effectiveness of standard post-processing procedures. Our results increase
confidence in EC, show in which conditions EC and BM estimates can be integrated, and
which methodological aspects can improve the convergence between EC and BM.
