You could.....but I wouldn't recommend it. Growing trees in a container will result in a natural dwarfing process but there is a limit as to how small and compact you will be able to keep it. Unless you were to go fully bonsai but that would require you to start with a much smaller plant initially.

Long term container culture of trees is a lot of work, just so you know :-)

You are right they are work lol. I have 3 sausage trees (kigelia), a longan, and a large Starfruit in containers that have to be in the gh here during winter. The containers are sunk in the ground and stay put and the greenhouse plastic comes down for 9 mos of the year. The trees get topped to 10ft to fit under the gh roof.

The sausage trees have 50ft capacity but not 100 like the birch. The birch would not have to be in the gh though. I have many other trees in pots but they arent huge types. I was just wondering if it was insane to even attempt a 100ft capacity tree.

What other trees have pretty peeling bark that stay smaller and can survive in zn 9a with humidity?

I decided to hold off on the River Birch and got a Foxtail Palm instead lol.