It seems to me that birchbark it is a little used in game. Only four possible applications. In this theme I only will list some subjects by which it is possible to do from birchbark.
1) can be used instead of parchment (so it and was used earlier).

2) From birchbark spun baskets and kuzovok, used for gathering of mushrooms and berries. Basket carried in hands, and kuzovok behind the back.


3) As did bast shoes. Convenient, though also unreliable footwear (some days of constant use destroy bast shoes).

4) Similarity of canoe of ancient Indians, only not from skin, and from birchbark.

5) For flexibility increase and consequently also capacities onions turned around birchbark.

6) The Siberian hunters did decoy for hunting for the deer, unmistakably imitating voice excited during the period rut animal.

7) The birchbark handle for knife doesn't allow it to slide on palm, and at the same time doesn't allow to sink.

8) As from birchbark did thuesen, special capacities for storage of liquids, saltings of fish, mushrooms, vegetables.

It only part of that it is possible to produce from birchbark, I hope something from this can be included to game.
Yours faithfully, Doppelganger