This picture is of a tree that has been pollarded. The top (mantle) will spread quite rapidly, whilst any growth to the main trunk would be removed to assist upper growth.
Pollarding is the complete removal of all the limbs of a tree leaving just a trunk section 2-5 metres high. The trunk then sprouts from the pollard head with multiple shoots. It was a historically common way of managing hedgerow trees and trees on commons to produce fuel wood and small structural timbers by cutting the regrowth (re-pollarding) on a cycle of 15-25 years.
Pollarding usually introduces decay to the main stem and once started the cycle must be repeated at intervals of 3-20 years, depending on species. If the re-pollarding cycle has lapsed, the tree may have become structurally insecure. However, it may be necessary to reduce the crown in stages (see below: crown retrenchment) in order to return the tree to an active pollard. Re-pollarding a lapsed pollard aggressively can all too often lead to its death.
Only young trees can be successfully pollarded for the first time and success may vary between species. However, regularly pollarded trees can live for centuries and the central decay of the trunk is a valuable habitat for different species of insects. |