Crown lifting/Crown Raising is the removal of selected branches and limbs from the lower part of the tree crown thus lifting the crowns overall height. Depending on the location of the tree, this process is generally performed to ensure vehicles and pedestrians can pass safely underneath avoiding accidents and injury.
This process can also assist in allowing more light to penetrate through the lower crown.
Crown lifting is also a way of preparing lower branches for future removal. Good practice of crown lifting should not normally include the removal of large branches growing directly from the trunk as this can cause large wounds.
These larger wounds can become decayed leading to further long term problems and possible Tree failure in the future.
Crown lifting on older, mature trees should be avoided whenever possible, or at least restricted to secondary branches or shortening of primary branches rather than whole limb removal wherever possible.
Crown lifting is a good additional method of increasing light into areas closer to the tree to allow other plants and shrubs to flourish. It may also be necessary to allow access under the crown for vehicles.
Crown Lifts should be restricted to less than 15% of the overall crown height and leave the crown at least 65% of the total height of the tree.
Crown lifting works should be specified to a fixed point/height, e.g. ‘crown lift to give 5m clearance above ground level’.
Local Council ground clearance heights for Public Areas vary form Council to Council. A good rule of thumb is, Public Highways minimum 5m ground clearance and Public Foot Paths 3m ground clearance.