Crown reductions can also be a measure when the root system of a mature tree has major decay making it potentially dangerous and unstable. However although it can help reduce the ‘sail’ effect, reducing the crown of a tree should not be used to reduce the chances of the tree blowing over in a storm. In this instance, crown thinning is recommended and professional advice from a trained Arboriculturalist, should be sought to ensure suitable measures are taken to mitigate the hazard presented by a defective tree whilst maximising retention.
There can be a limit to the extent the crown of an individual tree may be reduced. This is dependent on the habit of the particular tree species and its location. These as well as other factors can influence the amount of growth points that may be available when pruning. Removal of all foliage during crown reduction is not good practice as this can shock the tree into growing back faster and from additional points along branches creating future defects. Crown reductions should be carried out by a trained Arboriculturalist and not exceed reasonable amounts, conforming to BS3998:2010