Crown Reduction 
This is the process used to maintain the size of the trees crown (the foliage bearing portions), laterally and vertically and is measured in metres. This can help increase light into an area or to stop the tree from outgrowing its location. It can also help to reduce mechanical stress on individual branches or the entire tree itself by removing excessive weigh in the canopy. This is not suitable for all tree-types so it’s best to check with a tree specialist before considering.