tree conversion

[The_Sun]

2 part question

do birch trees convert back into broadleaf forest

and how big is the radius that it converts? how long does it take? these guys asre doing it, I think, just slowly.

[Arcanist]

2 part question

do birch trees convert back into broadleaf forest

and how big is the radius that it converts? how long does it take? these guys asre doing it, I think, just slowly.

Yes

3x3 small grids (11x11 grids) where the birch is in the centre grid.

Yes, they do a few tiles each growth stage.
If you want to convert it fast, plant lots of trees (any q)