Note that this is not the wood of an oak, but a woods of oak trees.  this concept has its own entry in OED, but it is always two words with a space or one single word, never hyphenated.  I am giving this spelling the JRRT tag.

• 07.023 in an oak-wood
• 08.042 a butterfly that loves the tops of oak-woods,

“oak, n.” OED Online, Oxford University Press, June 2017, http://www.oed.com/view/Entry/129461. Accessed 19 September 2017.