Pruning ornamental trees with the tree climbing technique

This technique is used, in particular, for pruning tall trees that cannot otherwise be reached. Tree climbing involves a suitably equipped operator climbing the trunk to reach the crown and perform the necessary work

Pruning performed with the tree climbing technique came into use in the USA at the beginning of the last century and then spread to Europe and Italy. Operators use special harnesses and support ropes to reach the tree crown and move about inside it, carrying out the necessary pruning and maintenance operations. Unlike working from aerial platforms that can only perform work on the outside of the canopy, the tree climbing technique allows operators to reach different points inside of it.

This technique is used to perform pruning on tall trees that cannot be reached with the bucket of a lifting platform, on trees overhanging slopes or river banks and, more generally, where there is no space to access with lifting platforms. But tree climbing is also used to fell tall trees in positions where their fall cannot be controlled, to shore up trees damaged by snow or affected by diseases, to monitor trees at risk of falling, and to thin out the foliage inside them. It is important to keep in mind that tall trees need to be pruned periodically, both to maintain their proper shape and improve their aesthetics, as well as to eliminate unneeded and dry branches (which can also be a danger to people) in order to facilitate the penetration of light and the circulation of air within the crown. In defining urban trees as ornamental trees, it must be said that the adjective ornamental is reductive. In fact, the urban tree not only serves an aesthetic function but also performs a whole series of ecosystem functions, from reducing pollution to protecting against climatic events and heat waves. This is why their care and proper management are important.

Arborist and tree grimper. It has been demonstrated that tree climbing pruners make great efforts to scale trees and operate inside the crown, experiencing both elevated cardiac activity and joint and muscular stress. Furthermore, there is a high risk of accidents, including serious ones, as they work high up with equipment that involves the use of cutting tools. To reduce these risks, operators are provided with training and both the equipment used for climbing and that to perform the work required is constantly evolving. Since 2006, Legislative Decree 2035/2003 has come into force (later merged into Legislative Decree 81/2008), which requires workers in high places on ropes to be certified by accredited trainers. Thus these operators must obtain certification through the completion of specialized training courses which essentially give instruction on arboriculture in order to learn the science and technique of tree management, on basic and advanced tree climbing techniques using ropes, on the use of the chainsaw and other tools used in tree climbing, and the felling of trees in particular hazardous situations by making successive cuts in order to control the fall of each individual piece of the plant.

Tree climbing operators are thus qualified professionals who, in addition to being in good physical shape, have excellent knowledge and skills not only with regard to tree climbing but also to arboriculture. During operations there are at least two operators: one on the tree, and one on the ground. Personal Protective Equipment (PPE) is important. In addition to a helmet, ear protection and glasses, when working with a chainsaw all clothing, jacket, trousers, gloves and boots, must be cut-resistant. All PPE must bear the European CE marking, which certifies its suitability for the use for which it is employed. The PPE and all the equipment discussed here and used in tree climbing should be regularly and periodically checked to verify its suitability for use.

Tree Access. There are three possible ways to access the inside of the tree canopy: with a lifting platform, with a ladder, with a rope directly from the ground. When possible to install, lifting platforms can be used when the height of the trees is greater than 15 meters in order to reduce the effort of the pruner making the climb. The first operation is to attach the rope anchor to the tree. The operator should never climb over the basket, exiting it only when fully hooked. The platform operator should also be a person specially qualified for this job. The ladder can facilitate climbing medium-sized trees. It is important that the ground is sufficiently firm and flat and the ladder is placed at the proper inclination.

Free climbing with a rope directly from the ground can be performed using different techniques with suitable equipment. This method involves the greatest energy expenditure. For this reason it is recommended that when making ascents greater than 15 meters, at least two breaks be taken to allow for energy recovery. Foot locking is a climbing technique used with double rope. It involves blocking the rope during the ascent by making a Figure-8 around the feet in order to obtain a support point. The climber uses his/her hands to grab the rope at a higher point, so as to lift up and repeat the operation with his/her feet. Alternating the movement of hands and feet makes it possible to climb quickly. However, it is a very exhausting technique, and there are alternative methods that can be used with foot locking systems to make the climb less tiring.

Equipment for access and movement within the canopy. In recent years, there has been a notable evolution in the equipment needed to safely perform tree climbing. The basic equipment is listed here.

A climbing harness is worn around the body to provide support when suspended and a safe stop in the event of a fall, an attachment belt is connected to the harness. A Big Shot launcher is the tool used to launch the line and bag (filled with lead balls) over tree limbs for attachment. The launcher is normally used for trees over 15 meters tall. Otherwise, the launch can be made manually. The ropes used are of different types and are made and designed for specific uses and to meet certain requirements, such as the stopping force and the breaking load in the event of a fall. The lanyard is a piece of rope connected to the rings of the harness. It is made adjustable by a locking system, and is used for movement within the canopy. Carabiners or belay rings, used to connect ropes to the harness and the tree, provide additional anchor points. Obviously the operator also has a tool backpack in which to place the various pruning tools.

Pruning Tools. The tools normally used by tree climbers for pruning are a saw, a telescopic pole with a saw, and a chainsaw. The manual hacksaw usually has a curved blade that allows cutting in both directions (forwards and backwards), has a soft, non-slip rubber grip and is equipped with a case with a safety catch to prevent automatic release. Chainsaws must be light, preferably battery-powered, and have a short blade. Top handle chainsaws, used with one hand, are ergonomically designed to be specifically used on lifting platforms and in tree climbing.