Pollarding is a pruning system in which the upper branches of a tree are removed, promoting rapid growth of dense foliage and branches. It’s often done to street trees to contain their size.
Only species with vigorous epicormic growth may be made into pollards (Oak, Beech, Willow, Maple, London Plane and Horsechestnut being the most common).
Once started, pollards need to be “re-pollarded” every 3-5 years.