Oak trees can be chopped for timber with use of the Lumberjacking skill. You can attempt to lumber at 55.0 skill - a higher skill grants a much better chance at succesfully harvesting the recource. You gain skill from all lumberjacking and your chance rises until the tree type becomes "trivial". A Trivial tree doesn't give skillgain any more and has a 100% success chance when lumberjacking.
First time I got Wood was at skill 38, but fail-chance is like 90%
Quality: 0.90 and 1
Gives 25 wood per tree