You did not specify what you mean by 'forest deficit'. Wood for shipbuilding was a finite and important resource. Many places had royal forests that were reserved for the king, specifically for shipbuilding, which required planing over decades-long time frames and vigilance against timber thieves.
Even when there were not reserved forests, legislation, restrictions and privileges related to cutting wood were much common.
Here a reference with many little details about Portuguese law:
Some scattered translated points from this document, you can find much more if you read everything and follow the references:
XV c. common formula in letters patent for privileges "lá onde mais lhes apraz" to indicate permission to cut wood in determined places
1471: prohibits export of wood to Castile and africa
1474: shipbuilders get privileges: they can cut wood anywhere, including royal forests, and do not pay taxes over wood
Shipbuilders in Vianna had many difficulties in obtaining wood. In the XV c., massive quantities of wood were imported without dizima (tax). (from Galiza and Asturias)
wood was needed for building vines, and there competition with shipbuilders. Farmers were obliged to plant oaks, etc. Prohibition of new shipbuilding companies for lack of wood
Almodovar people ask the king to cut woods to have more agricultural land (after the war is over). Their request is denied.
the leiria Council complains that many farmers stop working and go cut and transport wood, and this is why their crop yields are bad.
although there were vigilance and fines, the woods of alcobaça had many trespassers who cut wood.
To finish with an example from personal hearsay: in Quiaios, Portugal, local people tell that some of their woods were artificially planted and managed by the navy, and this is why they have so many big trees. They also tell that some of them were planted after a 'timber deficit'. (but this is local people talking and not hardcore documentation)
I guess that it were easier/cheaper to plant a forest with the correct species for shipbuilding in an accessible place, and to care for this forest (heavy criminal penalties for timber thieves) for some decades, than to search for the right species scattered in natural forests, or to buy timber elsewhere at wartime prices.
for a modern conservationist it may be frustrating to discover that a forest is not "native" or "natural". But it is common in european shipbuilding countries. It was also a relevant issue in England too.
PS: remember that import/export tax were the main taxes at that time (no income tax). To import/export something without tax was a huge privilege.