I think this may simply be a difference between written and spoken Japanese. But I've noticed that 木の皮 kinokawa is used regularly to mean "tree bark," while 樹皮 jyuhi appears to be more accurate but limited to signs or books or other written materials. Is 樹皮 used in daily conversation ever?
This question arises from trying to translate "birch bark canoe" (built by Northeast Native American tribes) and coming up with バーチ樹皮カヌー or something similar.