Reference
Bellassen, V., Viovy, N., Luyssaert, S., Le Marie, G., Schelhaas, M.-J. and Ciais, P. 2011. Reconstruction and attribution of the carbon sink of European forests between 1950 and 2000. Global Change Biology 17: 3274-3292.
Background
The authors write that "several parties to the United Nations Framework Convention on Climate Change (UNFCCC) are calling for 'forward-looking baselines'," so that country-specific scenarios based on forest age structure could be used "to credit only the part of the forest sink going beyond business-as-usual practices." And they thus proceed to derive such a baseline for all of Europe.
What was done
Using ORCHIDEE-FM - a process-based vegetation model that differs from earlier versions of ORCHIDEE by "its explicit representation of stand growth and idealized forest management" - Bellassen et al. applied the model on a grid across Europe to "simulate changes in the net ecosystem productivity (NEP) of forests with and without changes in climate, CO2 and age structure."
What was learned
The six scientists report, first of all, that the model they used "simulates carbon stocks and volume increment that are comparable … with inventory-derived estimates at country level for 20 European countries," providing "an upwards trend of forest NEP of 1 ± 0.5 g C/m2/year between 1950 and 2000 across the EU 25," ending with "a mean European forest NEP of 175 ± 52 g C/m2/year in the 1990s." And they say that "61% of the change in NEP [over the last half of the 20th century] was attributed to changes in CO2, 26% to changes in climate, and 13% to changes in forest age structure."
What it means
Once again - see Greening of the Earth in our Subject Index - we have more compelling evidence for the powerful aerial fertilization and transpiration reducing effects of atmospheric CO2 enrichment and what they can do for both the managed and unmanaged biosphere in terms of enhancing biological prodctivity.