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Evergreen

46 EVERGREEN Autumn

46 EVERGREEN Autumn (continued) ancient and veteran trees from failing mechanically. Reduction, however, should be avoided unless it’s absolutely necessary — in which case it should be carried out over a long period rather than quickly...to avoid dysfunction. “The majority of the trees that fall under my jurisdiction, particularly at Leigh Woods, are lapsed oak pollards. (Pollarding is a pruning system in which the upper branches of a tree are removed, promoting a dense head of foliage and branches. It has been common in Europe since medieval times and is practised primarily to maintain trees at a predetermined height.) “These have decaying stems with very big branches coming off that. The threat is that the stem will split apart and collapse — resulting in the loss of the tree. So while I can recommend a programme of end weight reduction to stop trees from splitting, the remedial work has to be assessed on a tree-by-tree basis. “Some rules have to be followed but each case must be assessed individually from the standpoint of the health and vitality of the tree. Looking at the vitality of a tree we have to ask several questions. How much growth is going on? How much epicormic growth is there? Are the leaves in good condition? Are they big, healthy and a good colour? Survival is unlikely unless there’s strong vitality. “It’s better to leave a tree alone if vitality is low because any form of cutting will cause damage. In some circumstances, of course, if you don’t do anything you’ll definitely Work that is needed is assessed on the ground . . .

2017 EVERGREEN 47 . . . and undertaken 40 feet up at the top of a tree. lose the tree — so it often amounts to a fine balancing act.” Tor says one of the main reasons why ancient and veteran trees are so important is because of the abundance of invertebrate life that dead wood supports, much of which may be very rare and vital for the continuity of habitat. As a result, part of the overall project has involved conducting a dead-wood invertebrate study by Dr. Keith Alexander, the country’s leading expert in deadwood invertebrates. “We knew we were likely to have a lot of very rare and nationally scarce invertebrates on our sites so we wanted to find out which species of insects etc. are associated with ancient and veteran trees.” Dr. Alexander set up traps in the trees and returned every month to monitor the results before producing a report from his sample study. His findings included a false darkling beetle last recorded in Leigh Woods in 1865 and a soldier beetle never recorded before in Leigh Woods. “While the main threat to pollards is structural failure, another is human activity around the trees. Are we parking on their roots for example? Root compaction causes trees to die. “If we put a car park where there are old trees we’re very likely to lose them. Any activity that’s happening around a tree that is bad for its health should be avoided. We’ve got many very old pollards and we’re planting and creating new young ones that will develop gradually. In the meantime we need to make some middle-aged trees age more

Evergreen Autumn 2017 online
Evergreen Autumn 2017 online
Evergreen Autumn 2017 online
Evergreen Autumn 2017 online
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