Edited by Len Phillips

Moving large trees is a specialty that requires experience and the proper equipment. Before modern heavy equipment was available to handle the weight of large root balls, trees 15 inches (38 cm) DBH and greater were moved bare root and eventual survival was low. Today large trees are moved with a soil ball that requires extensive knowledge of both arboriculture and heavy equipment. Mature size trees have been moved successfully, but the cost is very high, and it may take decades for larger trees to fully establish at the new site. Root balls can weigh from 100 to 500 tons and crowns can be up to 80 ft (53 m) tall and just as wide. There are very few specialists that are capable of moving trees of this size. Also, because of the size and weight, very large trees are best moved when the ground is dry or frozen. The rigid boxes and sophisticated lifting systems result in little root ball shifting, but add significant weight to the root ball.

Start the moving process by performing an inspection of the tree and site to determine the likelihood for survival and performance after relocation. The tree must be healthy and vigorous. Trees must be inspected for pests and disease, included bark, girdling roots, as well as cavities and decay. Structural integrity is also important since many trees are relocated to areas where targets may be different. Species must also be considered, as there are several that do not respond well to relocation.

Moving Trees
Special procedures must be used to minimize water stress in large trees. Proper root pruning prior to transplanting can help along with thinning the crown to reduce transpiration. Some contractors install sprinkler heads throughout the crown after planting to cool the foliage and reduce transpiration. Research suggests this practice may be necessary for only the few weeks before new root development begins. Watering will be essential during periods of actual drought. The use of treatments to prevent the spread of disease can also be beneficial. It is preferable to replant a tree to its original compass orientation in order to reduce the risk of sunscald on the bark.

B&B Moving
Trees small enough to use standard B&B root ball procedures of 12 in (30 cm) DBH are moved with commonly available tree spades mounted on winch trucks and cranes. The largest tree spade can dig a 14 ft (4.25 m) diameter root ball but because of the difficulty and cost of transporting this machine, it is probably only realistic to use this machine on large jobs with many trees to move.

Box Moving
Trees too large to move B&B can be moved in boxes constructed around a square root ball. First an over-sized square root ball is dug with a trencher or backhoe. After final shaping and root pruning with hand tools, the sides of the box are constructed with hardwood planks. Next comes the dangerous phase of digging underneath the root ball to install planks for the bottom.

The top of the root ball may also be covered with planks, especially if the tree has to be tilted to go under wires or a bridge. Large boxed trees are usually transported in the upright position because of their great size and weight. Utility wires and light poles may have to be moved and road permits obtained. When the tree is planted, the sides of the box will be removed, but the bottom will remain in place.

Box size
Determining the box size requires consideration of the species, trunk and canopy size, structure and size of roots, and site conditions. Under competitive bidding pressure, tree-moving companies may tend to put trees in boxes that are too small. Some tree species may be very sensitive to box size. The recommendation for these sensitive species is to use the largest box possible.

Cranes are used to lift the largest trees by both the root ball and the branches. Tensions must be even on all cables to avoid damaging the tree in one location. Experienced contractors use the sound made by the cable when struck with a hammer to judge cable tension (like tuning a piano string).

The method preferred in sandy soils where root balls may break is to lift the tree by one or two heavy steel pins inserted in holes drilled through the trunk. These pins are used to lift the tree in the upright position by both the pins and the root ball at the same time. The drawback of this method is the injury to the trunk, and the potential to introduce decay through these wounds in the trunk.

Once lifted, special trailers with over 100 wheels are used to distribute the load. Each wheel has a separate hydraulic leveler to keep the tree perfectly level at all times and a separate independent steering to maneuver in difficult places. Large trees may be too wide for roadways or too heavy for bridges and cannot be moved very far. Extremely large trees (up to 500 tons) can be moved with a crawler-transporter.

New Technique
A fairly new technique has been developed to move very large trees for short distances. The following digging procedure will ensure transplanting success:

• Root prune the tree and monitor its health for two months prior to the move.
• Cut a deep trench 30 feet (9 m) long on two sides of the tree and a 30 feet (9 m) long sloping trench on the opposite two sides.
• On one of the sloped sides, use a horizontal boring unit to drill 6 holes, 5 feet (1.9 m) apart underneath the tree's root ball.
• Then pass a steel cable through the bored hole to the other side of the root ball and attach it to a 5 ft. wide by 30 feet long sheet of steel, 5/16" (7 cm) thick.
• Attach the cable to a D-8 Caterpillar bulldozer via a cable and pulley system being anchored to a second D-8 bulldozer. The first dozer will pull the sheets of steel, one at a time under the tree. Repeat this process until all six sheets are under the tree.
• All the cables are connected to one bulldozer.
• The entire tree is then pulled on this steel sled to its new location where the steel sheets are removed one at a time.

• The tree is then backfilled and maintained, like any new tree planting.

Bare Root Technique
Using an air spade, an arborist can lift the entire root system when digging a tree and planting it bare root. This method greatly improves the probability that the tree will survive the move. The air spade is especially useful for transplanting specimen trees. The following digging procedure will ensure transplanting success:

1. Before using the air spade, hydrate the trees deeply for 72 hours prior to preparation for the transplanting. Clay soil blows best when it is damp while sandy soil blows best when it is drained, but still moist.
2. The minimum root ball should be at least 20 inches (52 cm) of root mass diameter for every caliper inch (2.5 cm) of trunk diameter.
3. Begin the process by digging a perimeter trench at the end of the roots. The soil from the air spade will be blown into the trench.
4. As the air spaded tree roots are uncovered, they are sprayed with water and covered with wet burlap.
5. When all the roots are exposed, they are gathered and attached by ropes to the trunk, in "pony-tail" fashion.
6. A forklift picks up the tree, under the trunk, and moves it and all the roots to the new location.
7. The roots are released, watered. and spread back in their original position.

8. The planting proceeds as it would with any bare root tree.

This transplanting technique should result in most of the tree's roots being retained. This greatly reduces the transplant shock and speeds the recovery of the tree.

Pruning
Pruning trees for relocation should be limited. The less foliage removed the less adverse impact. Pruning specifications recommend only the removal of damaged, dead, or diseased wood.

Fertilization, Supplements
Excellent post-planting care is always part of such a major project. Fertilizers or supplements provide little difference in the survival of relocated trees anytime before the tree is established. If the tree is transplanted to a site that is sterile, amendments are beneficial. If the tree is healthy before relocation, there will be a favorable level of nutrients and mycorrhizae in the root ball soil, so transplanting into the same type of soil should be okay.

Usually, amending the backfill for tree planting is not needed. Should a soil analysis reveal toxicity or deficiencies, corrective measures would be appropriate. Consideration must be taken when dealing with soils of different types since water percolation and irrigation practices will be greatly affected.

Cabling/guy wires
Due to the major root pruning that takes place when moving a large tree, anchorage is compromised. For this reason, all relocated large trees need to be guy wired while boxed and before planting trees. The cables should remain in place for a period of no less than two to five years. Proper cable installation and maintenance not only insures the safety and well being of property and people but also the tree itself. This rule should also apply to BR technique discussed above.

Planting
The actual planting of relocated trees is usually basic. The compaction of backfill not only increases stability but also affects air pockets that are eliminated by irrigation. When large air pockets are present, irrigation has a high probability of seeking out this space and bypassing the root ball. The compaction should be made with water soaking into the entire root ball excavation. Conduct a percolation test before planting to see if installing a drainage system is needed for the planting hole.

Maintenance and Irrigation
Maintenance and irrigation are critical in the success of relocated trees. If nearly 80% of the tree's root system is left behind during transplanting, the remaining root zone will be extremely sensitive to soil moisture levels. A fine balance must be found between too wet and too dry. Over watering can occur when:

• the tree is planted too deeply or at the base of a slope;
• the soil grade has been increased around the tree;
• irrigation lines are broken;

• the site has poor drainage.

Under watering occurs when the water does not percolate into the root ball. Soil watering basins or saucers can be used to increase percolation provided they are maintained.

Mulching is very beneficial in aiding the regeneration of root growth. Since newly developing hair roots are highly susceptible to desiccation, mulch helps maintain a moist, cool soil condition conducive to new root growth without constant irrigation.

Pest and Disease Problems
There is an increased susceptibility to pests and diseases associated with the relocation and stress to specimen trees. These issues can be dealt with by the use of pesticides for the prevention of insects. The most common disease problem encountered is Phytophthora, a root rot usually associated with over-watering. Irrigation management and applications of fungicide best achieve control of Phytophthora.

Establishment
The establishment period of relocated trees varies widely among species and the root/shoot balance. A minimum of two years or longer is required to establish a transplanted tree, using a standard maintenance program. After two years, maintenance demands are greatly reduced, lessening cost of care. Trees that have been relocated will require some maintenance and monitoring no less than three to four times a year.

Sources

• "BR Planting with an Air Spade", Archive #31, Online Seminars for Municipal Arborists, March/April 2010.
• Himelick, E.B., "Tree and Shrub Transplanting Manual", International Society of Arboriculture, 1991.

• Norman, Kerry, "Tree Moving with Success", TCI Magazine, June 2003

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