Pruning is a crucial part of maintaining the health of your trees and, when done properly, can help extend their life span. It involves the removal of dead or undesired limbs. Rather doing the actual pruning, many homeowners who feel that a tree has become too big and want to reduce its size end up topping the tree which is quite dangerous. 

Topping is the indiscriminate chopping of tree tranches to lateral branches or to stubs that aren't large enough to take up the terminal role. The topping practice is also known by other names, such as tipping, heading, rounding-over and hat-racking. However, topping is not a suitable method of reducing the size of a tree and indeed doesn't reduce future threat.  Here are some of the harmful effects of topping.

Stressing the tree

Topping eliminates over half of a tree's leaf-producing crown. You are probably aware that trees produce their food from the leaves. So removing them will certainly starve the tree and activate a number of survival mechanisms. For example, dormant buds are triggered, forcing the quick development of several shoots underneath each cut. This is because the tree needs to produce a new crop of leaves immediately or else it will weaken and die. Topping subjects the tree to a lot of stress. 

Decay

Appropriate pruning cuts are performed just past the branch collar at the spot of attachment. As such, the tree will biologically close that wound, as long as the wound isn't too large and the tree is in a healthy state. On the contrary, topping leads to cuts along the limbs between lateral branches resulting in the creation of stubs with large wounds that cannot be closed. The open wood tissues start to decay and the decay organisms soon move down along the branches without facing any opposition.

Sunburn

Leaves are produced by a tree's leaf-bearing crown and absorb sunlight in the process of making food for the tree. Once the leaves are cut, the remaining tree branches are immediately exposed to direct sunlight and heat, which may lead to sunburn of the tissues underneath the bank, resulting in bark splitting, cankers, and some branches dying. 

Rather than topping, the small branches should be cut from their spot of origin. Larger branches should be cut up to a lateral branch that's large enough to take up the terminal role. This technique of pruning helps maintain the natural state of the tree. 

If you don't have the skills to prune your trees properly, contact a reputable tree service and have them send in a professional arborist to carry out the pruning on your behalf.