I think, the birch-bark can be more useful in game.
Now it uses only for kuksa and some fishing lure.
In Ancient Russia birch bark was very accessable material and it was used for crafting many useful things like
'tuesok' - a little container for berries and other stuff
'korob' (box|basket) - a bigger container than 'tuesok'
'lapti' (bast shoes) - kind of boots, also can be made from rope, bass etc.
also, birch bark was used for crafting decorations, toys and QUIVERS (!)
and one of the important main roles of 'beresta' (birch bark) was using it for WRITING notes and documents - i think it will be useful in game, because leather parchments are hard and expensive to made.
Thank you,
Sorry for my english.