Keeping your forests...

[budweiser]

There is a definite mechanic to how trees will grow. Like if the tile is bordered by trees on more than one side, then the chance to grow a forest is greater.

The best thing to do would be set up sweet spots that have a high re-growth chance and chop that down everytime. I havent been bothered to ex[eriment with that yet.

 

[Iranon]

Grassland forests are still worse than improved tiles initially, but good enough as filler to let you regrow from the whip. Windmill + forests is only slightly behind mine + farm, and ahead once you can build lumbermills.
It can turn into a rather nice hippie economy with Environmentalism-boosted windmills for commerce and lumbermills for production... you can also save considerable investment on cap raisers.

If you don't need to work the tiles constantly and especially if you can do some sustainable chopping in a checkerboard pattern, go for it... and especially leave tiles shared between muliple cities.
Of course, go for whatever helps you in the short term if you're in the danger of falling behind (not getting enough land to compete, not teching enough to equalise by trades).

 

[WCH]

Or, alternatively, download FfH2, play as Ljosalfar, try to keep the AC low or get a lot of mages casting Sanctify, and enjoy having every city at ~30 population.