That's easy. We can make a simple law stating something to the effect of "for every three trees cut down, four must be planted."
I'm sure that the citizenry would respect that law; It would mean that whenever you set out to cut some trees, you also fill a herbalist table and when you return, plant those sprouts. The imbalance is to ensure that a backlog of growing and grown trees is produced, so that soon the forest will be refilled and resources can be gathered from it.
In the short term, it looks like the road east of brogdor is lined with unwanted cut trees- simply acres of felled timber. Even stumps left in the ground. Someone with a cart or two could collect a lot of that.