Management rules and external factors - INRA Montpellier

Economic criterion : NPV agroforestry no longer increases. d(NPV)/dt =0, or

NPV year n =NPV year n-1

Questions **and** comments

Is it playable to have a rotation duration under control of a rule This will

lead to different rotation length at each run of the model, which means that

the comparisons between the scenarii will be more complicated. Is it worth

doing

Is the economic criterion rule playable

At a given year, only the NPV time series of the preceding years is

available. It is not possible to predict the NPV of the next years without

running the model. It seems therefore not possible to use the rule, unless

the NPV variation is smooth, **and** we can infer that the optimum is reached

from the dNPV/dt study. (no local maximum required…)

We could suggest to run the model for more years than the possible

optimum, **and** do the analysis afterwards. Then, the model would find the

best time for tree harvesting from the whole time series.

Such an approach implies that the tree-tree competition is correctly

described by the model