Long-term measurements of the carbon balance of a boreal Scots pine dominated forest ecosystem

We measured on annual basis the magnitude and relative importance of different components of the carbon balance of a boreal Scots pine dominated forest ecosystem. The continuous 10-year-long measurement period of this study and the miscellaneous measurements of the components of the ecosystem carbon balance carried out at the same site are almost unique. The ecosystem was shown to be a carbon sink in all measured years. The average net ecosystem exchange (NEE) estimated with the eddy covariance (EC) method was (-)206 g C m(-2) a(-1) and the average annual accumulation of carbon into trees was 242 g C m(-2) a(-1). The above-ground litter production was 186 g C m(-2) a(-1) of which 92 g consisted of needles and leaves. The average respiration rates of the soil, canopy and stems were 646, 316 and 62 g C m(-2) a(-1), respectively and the TER deduced from EC measurements was 826 g C m(-2) a(-1). The average rate of the tree and ground vegetation photosynthesis was 982 and 114 g C m(-2) a(-1), respectively. In forest ecosystems the application of biomass equations to measurements of tree dimensions and increment cores can give a reliable and unbiased estimate of carbon accumulation into trees. The chamber based flux measurements are useful in showing short term response to changes in light, temperature and moisture conditions, but the generalization of the results over time and space is difficult.