The current note responds to the critical contribution of Dr. Eastaugh on Chiesi et al. (Chiesi et al. 2011). That paper did not aim at applying BIOME-BGC to simulate stand growth, which requires a thorough modification of the model functions. In contrast, only a parameter setting was changed in order to adjust the predicted carbon storages during the simulation of quasi-equilibrium conditions. The adjustment was calibrated on volume statistics derived from the Tuscany forest inventory and is suitable for regional scale applications.
The critical contribution of Dr. Eastaugh is welcome and testifies to the widespread interest in this important research field (
BIOME-BGC, at least in its original configuration, is not a growth model, since it does not simulate stand development and ageing, and trees are not individually represented (
This property is maintained in our approach. The BIOME-BGC versions used still simulate forests in steady state conditions. The modification proposed is only aimed at reducing long-term carbon accumulation in stems and coarse roots, which was found to be unreasonably high for some forest species (see also
Consequently, the new BIOME-BGC versions obtained are almost identical to the original ones, with the exception of the carbon accumulated in more stable tree compartments. These versions work with the same logic of the original model, and are therefore unsuited to simulate actively growing stands.
The strategy to account for departures from these potential conditions is based on a different rationale, which is fully exposed and discussed in