There are several factors that have to be evaluated before a fixed price can be given for felling or dismantling a tree. Size is the main consideration along with the location and the access.
For example a small tree at the bottom of a long garden, overhanging a neighbours greenhouse or Koi Carp pond that has to be dismantled and carried in small pieces through a recently redecorated house with a cream carpet may cost more than a larger tree in a rough patch of lawn in a front garden where the vehicle can park alongside.
Usually, straight felling a tree is not an option owing to space restrictions. Straight felling trees can be a hazardous operation and the damage to the ground is often unacceptable. Felled trees have their own hazards too as there are a typical stresses on the limbs and trunk The forces contained in stressed branches are very large and can cause serious injuries or death if not dealt with correctly.
There is a procedure for dismantling both felled and standing trees. Both need high levels of training to carry out safely and certification is a prerequisite for commercial operators.
Care must be taken to ensure that the debris falls to the ground in a controlled fashion to minimize damage to the ground. The team leader has to be led by the client and experience as to the amount of tolerable disturbance to ground surfaces as this will vary from client to client.
It is very difficult to carry out tree operations without some disruption to a garden or other open space. Lasting or permanent damage is to be avoided as this will be costly to rectify and may damage the reputation of the company.
A qualified arborist will usually require time and guidance to gain the experience needed to judge how and where to drop debris causing the least disruption. This aspect of operations is a little subjective. Different species of tree portray different characteristics when in bits.
Relatively small sections of oak, beech and ash cordwood will easily dent road surfaces if dropped from above 8-10 metres. Similar sized sections of poplar, willow, lime or conifer may readily cover twice this distance before there is a risk of damage to a tarmac highway surface.
Using lowering techniques or creating a mat from branch debris will protect surfaces from damage. Branches of any length, but with a diameter at the cut point of 35mm or less should be able to be dropped on all but the most delicate surfaces without causing damage. In most tree operations there will be an area under the tree or very close by into which the debris may be directed where either there is little risk of damage occurring or damage is acceptable or easily rectified, (thick concrete or bare ground for example).
The delicacy of the area around the tree to be worked on will have a direct bearing on the cost of the job and therefore the amount of time allocated to carrying it out.
From an arborists position within the tree, wherever the tree happens to be, the canopy should be segmented both mentally and physically. The dismantling of the canopy of most trees will begin at the lowest part and above the assigned drop-zone. A quadrant of the canopy will be removed back to the main stem. The extent of this quadrant will depend on the size of the canopy.
A small tree <10m may have a quadrant of 180 degrees or more as the climber can easily access the branches and control their decent into the drop-zone. A large tree may have a quadrant of 30-60 degrees. The climber will then ascend the tree removing all the limbs from within the quadrant. Visually it's a bit like taking a slice from a wedding cake.
Once the quadrant is opened up the climber can move up and down the edges of the quadrant removing limbs as he goes. Again, these may be removed entire or in sections. When using rigging gear to lower sections of large limbs the principles are the same. Sometimes it is possible to removeentirelarge limbs owing to the manpower available and/or no worries about damage to the ground around the tree.
Great care should be taken when doing this as the tensile and compressive forces involved are very large and the risks associated with this are amplified. There are advantages to dismantling a large tree over straight felling. A young tree will typically have upright growth and by virtue of the fact it is young will fit into most spaces.
Upright growth means that as the tree falls, its collapse to the ground is cushioned by the limbs, which tend to give rather than break or shatter, and the tree lies roughly horizontally and is low to the ground.
Large or very large trees are very exciting to fell in one but the delight is short lived as the clear up process tends to take longer and can be quite hazardous and unpredictable. The debris is spread over a larger area and there are always branches stuck in the ground that have to be removed. There is a standard methodology to dismantling a felled tree.