To prune out dead, diseased and damaged branches in trees (pruning back to sound growth point or source where possible.) Excellent for trees that are prone to trunk/branch failure caused by wind and trees which have established too many branches within the crown.
Crown lifting is the removal of branches lower down on the tree, which effectively “lifts” the under canopy of the tree away from the ground. This is often done by removing branches which may be impacting on paths, roads, or structures. Crown lifting lets more light pass beneath the tree and may help create a more aesthetically pleasing shape.
For most types of trees, the best practice is to avoid clearing more than one third of a tree’s height as the lower branches assist with the trees stability in strong winds. Most tree structures tend to have larger lower branches which require like any other tree parts require correct pruning techniques to minimize wounds which are entry points to pathogens and disease, ie; fungal infections, disease or rot.
Crown thinning aims to keep the general shape of the tree, whilst reducing the weight/load of branches in the crown. This lets more light into the canopy and allows air to circulate more freely. Light and air are beneficial to a tree, allowing the leaves to make more food (photosynthesis) and reducing constant moisture, increasing the risk of rot and fungal infections setting in.
Skillful crown thinning, as performed by a qualified arborist, gives the tree renewed growth and vigour, whilst managing the weight and structure of the tree. Unsympathetic crown thinning however can be damaging to a tree. Removing too much foliage, and too many branches from the centre could de-stablise a tree and make it more prone to damage or collapse in high winds.
Crown reduction is an overall minimisation of the crown by shortening branches from the top all the way down. Crown reduction is usually carried out when the tree has outgrown the space available for it to continue to grow. Because of the scale of this operation, crown reduction can be stressful and sometimes damaging to a tree. It should only be performed as a last resort, and only by a skilled arborist. Effective crown reduction is not tree topping or tree lopping. These practices harm trees and are not effective at making trees healthier or more safe.
Weight reduction involves shortening over-extended, end-heavy lateral branches throughout the canopy. This is done for the same reasons as crown reduction, but is limited to just lateral branches and does not include reduction of the height of leading stems in the upper canopy. This is the primary pruning method to improve safety and reduce the risk of falling branches.