This page currently in the process of being written.
The lumber boost attribute affects the amount of logs you get from chopping.
1 = floor(x/25)
So we have to invest 25 points just to get +1 log?
I believe its 25 to get a extra log every time so 12 would be like 50%. You get 1 extra almost every time after upgrading the axe same with pickaxe. Like copper axe.