A simple world editor check would do the trick. The object editor has information for that.
Humans actually chop 10 times, and can only store 10 lumber, unless you upgrade lumber harvesting, so do orcs.
Ghouls chop 10 times, and store 20 lumber.
And wisps give you 5 lumber every 5 seconds, then they switch trees.
I'm not sure though, because I don't play melee maps, but I used the info in object editor.