Pollarding is a common method of tree management where the main leading stem of a tree is removed to encourage regrowth. The regrowth that then occurs can be regularly removed (re-pollarding) back to the same point (the pollard head). It looks neat and keeps trees at or below a specific height therefore it is a popular method of tree work. There are also benefits for the tree and for safety.
Pollarding creates a dense canopy of vigorous new growth which looks attractive and creates less shade. Since the leaf-carrying branches are thin, there is less crown weight and therefore less wind resistance and of course less to fall. The act of pollarding a tree also is said to increase its lifespan as it keeps the tree in a partially young state.