Structural pruning is a type of pruning typically performed on young to middle-aged shade and ornamental trees. The objective is to create a strong and healthy structure so that trees are sturdier under wind and other loads, and less prone to failures, and so they can live full and useful lives in the landscape.
Live leaders and lateral limbs are “subordinated” or reduced, to slow their growth, so that the main stem can develop dominance again.
Similar principles apply to pruning of ornamental trees. They can often grow to become wider than they are tall, and more prone to breakage. Structural pruning can reduce the crown spread so that the likelihood of failure under wind or storm loads is reduced. It can also shape the tree to fit its place in the landscape, providing desired benefits.
The sooner in the life of the tree that structural pruning is started, the easier and cheaper it is. Waiting until the tree is mature often means bigger pruning cuts, cabling and much greater expense.