Based on my other question, here is a simpler hypothetical excerise that isolates that time cosntraint issue all together:
Wood types A and B have the following m3 per ha
Wood types regenerate at the following rate (m3/ha):
wood type A sells for $100/ha while type B sells for $75/ha. Prices will increase 3% per period Optimization: Maximize the revenue of the farm over a 40 year period as well as period over period assuming 5 year periods and at that after 40 years , 70% of the forest is still planted. Attempted solution: Optimization functions:
Constraints:
Question: How can I incorporate the time aspect of yields, regeneration, and optimizing over multiple periods into the problem? asked 18 Jul '13, 08:02 dassouki 
First thoughts/clarifying question:
You can create a variable for the number of hectares indexed on:
as well as the number of hectares harvested in a period. This is a bit redundant, but is probably easier to work with (I'm assuming the model is more complicated than you are saying, so I'd suggest very explicitly modelling everything, even though you could probably just solve this particular problem analytically). With that, you could easily write a single objective for the NPV, and the constraints would say something like "the number of 10 year old type A trees in period 5 is equal to the number of 5 year old type A trees in period 4 minus the number of hectares harvested". answered 18 Jul '13, 18:44 Iain Dunning Thanks, I think you cleared up the problem for me enough to understand what I need to do.
(19 Jul '13, 15:57)
dassouki
