Air-tool transplant: Norway Spruce Part 2
November 22, 2009 by Deborah Howe
To continue yesterday’s post on the bare-root transplanting of a Norway spruce at the Perkins School for the Blind in Watertown, MA:
The crew uses a heavy canvas strap wrapped securely (more than once) around the trunk, and pads the Bobcat fork bracket. This tree's flat back meant it could be pulled securely up onto the forks without tying up branches; other trees would need to be tied up for easier spading and transport. Here, the forks are poised to push under the root ball, just below the wire basket.
Rolando prunes thin fibrous roots from under the basket, to release the root ball from the ground. Most of the root mass has already been blown out.
Spruce on the move. With almost all the soil blown off the root mass, it is light enough for the Bobcat to carry the tree easily across campus. Canvas straps secure the tree to the Bobcat; Rolando rides along just in case.
Closeup of the root mass. Virtually all of the roots on this tree were quite thin, and they made a dense mat that extended about nine feet out from the tree's trunk on several sides.
Mynor had dug out the hole with the Bobcat while Sonia and Rolando blew out the soil from around the tree. This site, next to a busy campus parking lot, challenged the crew to place the tree carefully. Cars were parked just to the right of the orange barrier in this photo, and other relocated trees ringed the dish on two other sides, so maneuvering to get the tree in place was a bit tricky. It's relatively easy to spin at least a small B&B tree to the right orientation; turning an air-spaded tree requires a bit more forethought. In this situation, a bit of three-dimensional visualization was necessary to be sure that the flat side faced away from the parking lot.
Sonia and Rolando used a rake handle and tape measure to determine the root mass's depth before adjusting soil depth in the new hole.
Additional native soil is added and compacted to make a pad under the trunk. When in doubt, it's better to place the tree slightly higher in its new location than to risk it settling deeper once it has been backfilled and watered in; tamping the soil firmly under and around the roots right at the tree's base helps insure both that the soil won't subside and that air pockets are eliminated.
Rolando guides Mynor in setting the tree in the right spot. Good communication is key through this entire project, and these guys were excellent in coordinating their work with each other.
Rolando and Santo shovel native soil under the rolled-up root mat, to secure and level the tree before its roots get spread out.
Sonia and Rolando spread soil under and over the roots as they unroll them from the bundle. Note that they are using soil excavated from the site, with no amendments. Bare-root transplanting eliminates the difficulties associated with moisture transfer between two types of soil (root ball soil and soil outside the root ball), which makes establishment in its new site less stressful for the tree.
With backfilling complete, the crew builds a berm.
With the berm in place, Sonia waters the backfill thoroughly. Some crews shovel in the backfill and water simultaneously, "mudding in" the tree for extra stability and the complete elimination of air pockets. Mulch will go on this new planting next, and then more water. Note that you can see the root flare, now that the tree has been excavated from its original root ball and planted at the proper depth.
Project site: The Perkins School for the Blind, Watertown, MA
Project manager: Sonia Baerhuk
Project crew: Rolando Ortega, Mynor Tobar, Santo Masciari