Crown thinning is the selective removal of internal branches evenly throughout the tree to reduce the density of the crown, whilst at the same time not reducing the overall size or shape of the tree. Crown thinning is designed to reduce damage that could result from crown resistance to strong winds. Crown thinning may be carried out to admit more air and light into and through the canopy
Crown reduction reduces a tree's crown while still maintaining its natural shape. Crown reduction pruning is most often used when a tree has grown too large for its permitted space. This method, sometimes called "Drop Crotch Pruning", is preferred to topping because it results in a more natural appearance, increases the time before pruning is needed again and minimizes stress on the tree.
Crown lifting is the selective removal of the lower branches of a trees crown to increase the distance between the base of the canopy and ground level. This type of pruning should, if possible be carried out before a tree reaches maturity in order to avoid large wounds. This allows more light through and can prevent obstruction.