sublimation of H2O wont take place until pressure is less than .006 atm ( top of Everest is about .34 atm). So the ice wont sublimate much in your average freezer( a tiny bit will). I don't see how freezing would help the wood in anyway, it's more likely to do harm, trees go to great lengths to prevent freezing, and the thereby the ice crystals which destroys cells. Its possible that throwing a stave, cut in the colder months, doesn't even freeze when you throw it in a freezer.