Not going to lie, I tried to mimic this palette as much as I could by eye retinaleclipse.com/treepalettes3.png I didn't really accomplish what I set out to do in the beginning, but I'm happy with the result. Will definitely be doing more trees later on.
Here's a palette comparison if anyone is interested (the 15 colour palette being the one I made)
I think my palette is more stiff, in the sense that I used more of a flat ramp whereas the other one was much more flexible with it's saturation and hue, it also shifts a lot more towards blue.
It was nice taking a break from side-view art though :P
EDIT: WIP gifs for the trunk and tree http://i.imgur.com/DLXlB3T.gif i.imgur.com/yFTnciM.gif