February 1, 2008

Tree walk: Utility pruning on Blake Street

Utility pruning is the removal of branches or stems to prevent the loss of service, prevent damage to utility equipment, avoid impairment, and uphold the intended usage of facilities. Only qualified line-clearance tree trimmers or qualified line-clearance trainees should engage in line-clearance work. Arborists' Certification Study Guide, Sharon J. Lilly, 2001.
The utility pruning in the photograph occurred on Blake Street, south of Telegraph, in Berkeley. The tree is a topped redwood. Topping is an inappropriate and harmful form of tree pruning. (Arguably, a redwood should not been planted beneath overhead utility wires.) Lilly writes,
Severe heading causes branch dieback, decay, and sprout production from the cut ends, resulting in a potentially hazardous situation once the sprouts become large and heavy....If a tree has been topped previously...crown restoration can improve its stricture and appearance. Restoration consists of the selective removal of watersprouts, all stubs, and dead branches to improve a tree's structure and form....Restoration usually requires several prunings over a number of years.
A Davey Tree crew was pruning the redwood. I do not know what contract relationship the City of Berkeley has with Davey Tree, but I did find a 2007 City Council memo about tree removal services with West Coast Arborist, Inc.

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