I believe you need to have GM lumberjacking to get the fragments, but I could be wrong and you just need a certain skill level. I usually get about 4-5 for every pack full of logs, so they are fairly abundant. That said, if you still need them, I have some for you, although I will be going back to bed in a few minutes (only insomnia brings me here now). I'll actually drop 10 fragments into one of the chests in Luna (the one that is by itself), so if you get this soon enough, they should still be there (unless someone has more of a packratting problem than me and thought they needed 10 bark fragments!!!). Anyway, good luck finishing the quest!