Cutting of trees and shaping of crowns

Cutting of trees

Trees may have to be cut for various reasons:
– severe damage during a storm;
– old and does not perform its function as an attractive landscape element;
– infected with dangerous diseases, e.g. fire blight;
– tree has decayed and become dangerous;
– tree does not fit in the landscaping plans of owners;
– other reasons.
Trees can be cut in two ways: whole or gradually from the top.

Whole-tree cutting is possible only in places, where there is space on the ground that is equivalent to two lengths of the tree. If a tree is cut in urban areas with intensive pedestrian and vehicle traffic, the felling area should be roped off by means of a special tape. There should be a person in the secured area that communicates with bystanders and prevents unauthorized access, if needed.
In the case of whole-tree cutting, the felling notch and felling cut should be made with extreme precision for the tree to fall in the planned direction. In urban areas, it is often just a narrow strip of land. If needed, the felling direction can be adjusted by means of various aids, for example, ropes, a mechanical winch or tree felling wedges.

Gradual cutting is required in places where whole-tree cutting is impossible. It is possible to rely on various climbing techniques or rent an aerial lift. Cutting should start from lower branches. If needed, the cut parts can be lowered with ropes, winches, cables, pulleys, hooks and other aids. When all the branches are removed, the trunk can be cut using the same method.

Pruning and shaping of trees

Pruning of crowns is mostly required in urban areas, where people strive to mould the environment and landscape to their tastes. Pruning is also needed for safety reasons to remove dry, broken, decayed or other potentially dangerous branches.
Urban trees may have natural or pruned crowns. In the former case, please remember that the purpose of pruning is to have a healthy, vital and aesthetically pleasing tree with a characteristic crown shape. Cutting branches that will deprive the tree of its leaf surface area should be carefully considered, as this may cause stress and undermine the vitality of the tree. It is not recommended to remove more than 20-30% of the leaf surface area in one year.

Natural crowns

Maintenance of crowns

During maintenance of natural crowns, the unwanted competing tops and dry, dying, diseased, scratched, broken, split, inward growing or damaged branches are removed.

Thinning

During thinning of a crown, branches smaller than 5cm are pruned. A tree with a thinner crown allows more sun and air in, becoming safer in storms. Moreover, it does not create excessive shading. If the crowns of new trees are thinned, the spread of primary branches can be optimized to ensure a stable structure.

Raising of a crown

Most natural crowns reach as far as the ground. However, this is not acceptable near roads, streets or pavements, where crowns have to be raised. In green areas, this is accomplished with young trees by regularly cutting lower branches, until their diameter reaches 5 cm. On the road side, branches cannot be lower than 6 m above the ground, and on the pavement side – 2.5 m above the ground.

Reduction of a crown

Crowns are reduced when the branches have grown too long and reach into facades or when the trees are old and a proper reduction would prolong their life. However, every effort should be made to maintain the natural shape. To reduce crowns, the branches are pruned back to internal secondary branches or removed by cutting near the trunk or a larger branch. In the former case, the cut should be made at a smaller branch, whose diameter equals at least one-third of the diameter of the cut stem.

Cabling and bracing

Cabling and bracing are needed if the trees have disproportionate and unstable side branches or several trunks that might split during a storm and endanger people and property. Usually, such branches or trunks are not cut, but secured with a dynamic or a static system for safety purposes. The dynamic system consists of a special cable and cambium protectors that are used to secure dangerous trunks by attaching the cable at a distance equal to 2/3 of the distance from the dangerous area to the end of both trunks allowing for some sag. The tree, unaware of the system, then continues to strengthen its weak point. However, during critical gusts of wind, the system tightens, preventing the branches or trunks from splitting and falling. The static system does not move, for example, like a rod inserted in a trunk. Thus, it should be used only in critical cases, when a dynamic system cannot deliver the desired result. In some cases, both systems can be combined for added security.

Pruning of young trees

Shaping of young trees usually takes place in nurseries. As such trees grow very quickly, with some effort it is possible to shape an aesthetically pleasing, strong and safe tree that will not require a lot of maintenance in the future. Young trees are pruned with scissors or handsaws. Usually, the wounds are small and heal very quickly.

Pruning of old trees

Though old trees are valuable, they are often dangerous. Crowns of old trees are often reduced, the dead and dry branches are removed, and, if needed, cabling or bracing systems are installed, thus extending the life of trees in green areas and reducing the danger that these trees pose to people and property.

Maintenance of pruned and shaped crowns

Quite often in green areas, there is limited space for trees to grow and form a natural crown. In such cases, it is possible to shape the crown for optimal use of the available space.

Shaping and pruning

By pruning unwanted branches, it is possible to create crowns in a desired shape and size that look stunning in flower beds, for example, spheres, tablets, cones, tunnels, cylinders and other shapes. However, when the crown is completed, pruning and shaping should be done regularly. Moreover, not all species of trees or shrubs can be shaped.

Espalier

According to the espalier technique, one-year shoots are pruned and tied horizontally to create the desired pattern. At the beginning, this method was used to shape fruit trees, but now it is also used in green areas, as espaliered trees take only as much space as is planned for them.

Pollarding

Pollarding is one of the friendliest pruning methods of shaping tree crowns. Due to regular pruning of branches at the same place, the tree develops “lollipop” ends that look especially impressive when there is no foliage. The pruning should be done with extreme care and accuracy, and new branches should be pruned once a year, but no less than once every three years. Pollarding is not suitable for all species of trees, but it can be used in linden, elm, willow and other trees with many dormant buds.

Bonsai

A bonsai tree is miniature, but has the same crown shape as a large tree or a crown that resembles a mountain pine. This method is very time-consuming and work-intensive, as the branches and roots should be cut on regular basis. However, the result is well worth it.

Problems

When trees are cut or their crowns are shaped, we often face various problems that result from the lack of knowledge or action that eventually need to be solved.

  • In urban areas, young trees are often not cared for properly or thoughtfully during the first few years after their planting. Most probably, due to limited resources, the required work is done only once every five years. During this period, the tree grows large primary branches that have to be removed to raise the crown, leaving large wounds, stressing the tree, undermining its vitality and increasing the possibility of fungal infections. Also, quite often too many branches are pruned off at the same time (more than 20-30 % of the leaf surface area). Incorrect care of young trees adversely affects their development often resulting in problematic trees and additional future costs.
  • Tree topping is one of the cruellest pruning practices, in which the tops of trees and large branches are cut irrespective of the tree physiology. The tree sustains large wounds, where rot develops and gradually destroys the tree. Tree topping demonstrates a total disregard for the safety and vitality of trees. Topped trees become a liability, and their care and maintenance require extensive work and considerable funds. Furthermore, topped trees lose their appeal and become quite unattractive.
  • Due to urban development, tree roots are often damaged, which becomes visible in their crowns – the branches or even parts of the crown die, the tree withers, the leaves may never open and eventually the tree has to be cut. Most often, the roots suffer during the construction of road, communications and other urban infrastructure, as well as due to coverage with a thick layer of various materials and spraying of materials like sodium chloride.
  • Trunks are damaged due to careless clearing of snow, use of grass and hedge trimmers, as well as the behaviour of dogs. In such cases, it is necessary to change the attitudes and approaches of public and responsible authorities to trees and their care in urban areas by means of extensive awareness raising campaigns, improvement of imperfect laws and the implementation of tree safety measures in green areas.
  • Crowns of trees are pruned in unsuitable weather conditions, when the temperature is below -5 degrees. The wounds freeze and cause splitting that facilitates decay.
Written by: Aigars Priede

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