S.H.
Get a table top sized tree, and put it up on a table he can't reach.
This will only be for this year probably, then when he gets older, a regular tree is fine.
Another option is to get a "fake" tree, a small one perhaps 2' tall or something.... that you put in another corner of the house, and THIS one, he CAN touch.
You just teach him that that is "his" and the other one is "not" to touch.
And yes, you just teach them not to touch the tree... and they do learn. Or, you put the tree in a room which has a door...and then you can close the door so that he can't go in there and touch the tree in case you are not able to eyeball him every single second of the day. Yes, the tree can topple over even like anything else that is tall. So it's a safety thing too. Or you just put "safe" ornaments on the bottom half of the tree that you don't mind if he touches it or "breaks" it by accident.
This is what we have done and it worked.
Good luck,
Susan