How do trees repopulate and how long does it typically take? I haven't found any sort of seeds and haven't noticed any saplings around, and I don't want to chop down too many trees at once.
EDIT: Just found a sapling, they seem to be tiny things... still curious on how quickly they repopulate though (mainly talking about birch just to clarify).
So my brother and I set up on the edge of a forest and there was a coastline some distance away. We began logging to build our house, couple of tress sometimes, then five or six, then more and more until we found that we were nearing the coast line. Our house is not at the edge of the forest any longer. Then we decided to take trees from elsewhere to preserve what was left of the forest area around us. Took about 10-12 RL days I think but I finally started seeing some saplings return and it takes about 1-2 RL days for them to become a full grown tree.
Now I don't know if this is part of the game or not but in a different area I noticed saplings appear faster if the stumps were removed. I saw a section regrow in about 3 days. So I immediately went home to our "forest" and took out all the stumps. So I hope they start to grow faster.
And finally here's my biggest tip for you. My brother and I did not have logging efficiency in the beginning, and that is most of the reason our forest got clear cut so dramatically. I recommend get up to level 3 before doing any serious logging. Its amazing, just two or three trees will fill up a whole chest. After level 3 the skill cost is a lot higher so I'd stop there, but even level 3 makes a major difference.
If you don't completely take down most of the trees in the area. Then they will grow back almost over night. If I need to log I tend to do it with breaks. Like I might get the trees near my house, but leave most of them. Then leave them alone for 2 days, and go after another area.
Note it is possible to wipe out all the trees