The object is to preserve rare trees. Use of wood from these trees in manufacture and sale is prohibited unless "grandfathered."

The regulation is strongly enforced by the U. S., but I have not looked at Canada's prohibitions. Many of the same regulations have been enacted.

SRS link is for the U. S., not Canada. Moreover they prohibit Canadian seal furs and seal parts, objects made of walrus ivory, narwhal, some native-made objects, etc.

Also Cuban and other goods allowed into Canada but prohibited in the U. S. cannot be brought into the U. S.