Trees do not grow surplus branches but may be able to tolerate some loss. Any cut creates a
wound which will remain with the tree for the rest of its life, never healing but sealing over.
A good reduction will retain an aesthetically pleasing crown outline, generally mimicking the original. This should be specified using linear measurements e.g. reduce height from 20m to 18m and spread from 7m to 5m. Bringing the height down and spread in is similar to reefing the sails on a yacht. This can: reduce loading on weak sections and therefore reduces risk of failure; reduce shading; and maintains size. However, some of the downsides include: reducing the sugars available to strengthen weakened sections; stressing the tree, potentially leaving the tree more susceptible to pathogens and other stresses; reduces the wind-induced movement necessary to stimulate reaction growth and strengthen weak areas.
A crown lift will remove low branches, frequently carried out where access is required for vehicles beneath trees but can also be carried out for aesthetic reasons. A crown lift should be specified using a vertical measurement from ground level to a specific part of the crown e.g. crown lift will give 4m clearance from ground level to foliage. On mature trees larger branches that carry a significant proportion of crown will likely be retained, even if they originate within the specified measurement, where removing them would result in the loss of a significant part of the crown or would create large wounds on the trunk.
Topping Vs Pollard:
‘Topping and Lopping’ is the indiscriminate internodal cutting of primarily mature trunks (topping) and branches (lopping). This creates large wounds and bundles of dysfunctional vessels, it removes a high proportion of the crown if not all of it, and subsequently results in starvation of the root system with decay entering from the rotting roots. Under certain circumstances the tree may send out masses of shoots in an attempt to regrow the lost crown, which will then grow rapidly but structurally weak. While the tree is slowly dying (assuming it had high energy reserves in the first place and doesn’t die immediately) it has no more aesthetic appeal than a large stick in the dirt, perhaps with an occasional bush of leaf stuck on top. Some species of tree survive this treatment but they survive Despite it, not Because of it. Very occasionally (but rarely) there may be justification for this treatment; for example, where a tree has become so weak it cannot support a crown but is still of some importance, such as providing bat habitat, then topping may be a suitable option. If a chainsaw operator tells you they will ‘top’ or ‘lop’ your tree for you without very good reason then kindly decline their offer and send them in the direction of ArbAdvice Training and we will try to educate them.
Pollarding is not the same as topping. Pollarding differs in that it is relatively young wood that is being cut, creating relatively small wounds, carried out on a regular basis such that the tree adapts growth chemically and anatomically to tolerate the cyclical cutting. Not all species will tolerate pollarding in the same way that not all species will coppice. Pollarding and coppicing are historic forms of management where the intention was to exploit the rapid straight growth that arises from an established tree rapidly regrowing the lost crown. Where the young shoots of coppiced trees may be eaten by browsing mammals the shoots on a pollard are high out of reach.
Carried out usually at a young age to create a good structure and remove any branches which may develop with weaknesses.
Fruit tree pruning:
Where fruit production is the aim then cutting out old and less productive branches can stimulate young and productive shoots. Allowing light to penetrate the crown allows the fruit-bearing branches to photosynthesise more giving more sugars to the fruit.
Where no other option is viable then removal of the tree is the last resort.
The tree is cut down to near ground level with one cut, where there is space to fell safely.
The tree is removed in sections where space is limited to fell, typically using rigging ropes and pulleys to lower sections.