Fig. 2.

The 2001–2010 mean carbon sink in global forests partitioned between old-growth and regrowth forests, as calculated by LPJ-GUESS forced by GFAD. (A) Total uptake in old-growth and regrowth forest. Dark green shows the fraction of the regrowth sink that would have occurred in the absence of any environmental change since 1870 (CF), while the light green bar shows the additional flux including all environmental forcing (FF). (B) Total forest area in old-growth and regrowth categories. (C) Uptake rate per area. Results from sensitivity studies are illustrated with additional symbols. The blue square shows the sensitivity to assumptions about the fate of cleared material (Methods, S1), the orange square to assumptions about land-use type before forest regrowth (S2) and the red square to the assumed rate of disturbance in spin-up (S3). The downward pointing arrow is forced by the 5% confidence limit of the stand age distribution and the upwards pointing arrow the 95% confidence limit. For regrowth forest, these sensitivity simulations are shown both for CF (left of regrowth bar) and FF (right of regrowth bar). By definition, the sink in old-growth forest is only driven by changes in environmental forcing (FF) and hence has no CF component.