A few posts back I mentioned my February 2009 article in Lawn and Landscape Magazine on bare-root tree transplanting using an air spade. That article was preceded by my December 1, 2008 article in American Nurseryman, , in which news of the technique debuted. Both articles describe the workshop at which several trees — a Juniperus virginiana, a couple of Acer palmatum, a couple of Betula pendula ‘Gracilis’, among others — were spaded and moved. Both articles outline how to carry out the process, though the Lawn and Landscape article is a bit more explicit. And they compare the merits of different methods of transplanting (tree spaded, ball & burlap, and air spade), including how cost, speed of operation, and effect on tree health may vary.
The beauty of using an air spade to transplant specimen trees is that so much root mass can be preserved and moved with the tree. The following photos of a dwarf Japanese maple (Acer palmatum dissectum), lent by Matt Foti, illustrate just how effective at saving roots this technique is. Matt and his crews are using an air spade routinely now in transplanting work, because it preserves the tree’s resources so well, minimizing transplant shock and easing re-establishment. They moved this tree in early September of 2008. Take a look:
Acer palmatum dissectum awaiting its move. Soil under the tree has been lightly spaded to check surface roots.
Same tree, roots now exposed by the air spade. Note how far beyond the tree's dripline these roots extend.
Tree being lifted up for the move. The crew has wrapped its trunk and main limbs, to avoid injury; guy lines insure that it won't tip in transit.
Wrapping thoroughly during this kind of move lessens the chance of bark injury.
Tree in its new location, backfilled and awaiting thorough watering. No staking is necessary, as most of the root mass has been preserved and will continue to support the tree in its new home.
Deborah Howe
Taking Place 
Hm. Makes me wish I had one of those for the beautybushes I plan to move this week!
Just saw Matt Foti doing a bare root transplant on Ask This Old House! Very cool.
Hi, Michael — Thanks for your note — I’m glad to know that the new segment is airing; it should help get word out. Remarkable to see what a tree’s nether parts look like, isn’t it?
Hope you’re well — Deb
The root mass looks quite different than I expected. More delicate. Particularly when you see them laying the network of roots back out in the new location, you get a sense of how much root is lost in a common burlap transplant.