(a) Percentage reduction of the whole canopy of the tree.
This can be done to increase the light to the house, grass or maybe a ‘veg patch’. A light reduction can also be known to reinvigerate an older tree and give it a new lease of life and a few more years.
(b) End weight/reshape
Trees naturally self optimise, meaning they grow towards the available light. The shedding of limbs is a common, natural mechanism for trees. However in a private, urban environment this can be extremely dangerous for property and public. Dangerously heavy limbs can be reduced in size without the need to loose the whole tree.
If however, the tree is not particularly dangerous but has grown misshapen it can be skillfully pruned to create a more natural amenable shape and preventing the growth of dangerously heavy branches.
(c) Crown raise/thin
Removing some of the lowest branches of the tree and/or selectively thinning the overall canopy evenly. Again this can be done to increase light to the garden/house and can help the over vibrancy of the tree.