Kyushu Danji wrote:
That makes complete sense, but could the air layer still work by cutting back on foliage and unwanted branches, thereby reducing the amount of roots necessary to properly support the tree? I'm only asking because I have a few going at the moment and I just want to be safe and make sure they survive. (Sorry for getting off topic!)

Most gardening practice is common sense.. and its right on topic ...
Depending on the piece being layered, I often reduce the growth when removing. As you have them going already, if your worried about them not surviving you could leave them & remove during late winter. The vines are dormant then so there is nothing taking up resources, meaning less need for a big root system.
How long have they been on the parent tree for?
If theres roots showing you could unwrap & sort them out, removing those growing down or at the wrong level, then rebag, or better still use a pot/box & replace the sphagnum with your usual growing medium. When you do finally remove they will have a great nebari in the making & a bigger root system to allow for more wood to be kept. I have seen layers left in place for 2-3yrs with root work being done each season as per a normal bonsai, that was on large mature trees which needed a new nebari grown. They still need more care when finally removed but less reduction in the plant is needed.
If you can get hold of a copy check BT 48 & 49 for the story of a large mature beech that was layered over the course of 2yrs, #48 also has a great article on layering, with lots of examples to show the possibilities with numerous species. I had done more than a few before seeing those articles but since then they have contributed greatly to my successes... doesnt mean i always follow my own advice or experience (
viewtopic.php?f=104&t=4245 and
viewtopic.php?f=131&t=6331)
Any chance we can see some pics?
Matt