Post: #2

If I understood your question right, it is in sphere_region, you can assign the chance of getting each resource:
[REGIONRESOURCE mr_tree]
AMOUNT=9,30
REAP=i_log
REAPAMOUNT=1,3
SKILL=1.0,80.0
REGEN=60*60*10

this says the skill needed to chop this kind of log, the amount and time it takes to respawn

[REGIONTYPE r_default_tree t_tree]
// All trees produce wood by default.
RESOURCES=60.0 mr_nothing
RESOURCES=40.0 mr_tree

this says you have 40.0% of chance when you hack a tree to spawn a mr_tree instance and 60.0% of chance to spawn a mr_nothing (which will get you the message "fail to produce any useable wood")