City Trees is a premier publication focused on urban + community forestry. In each issue, you’ll learn how to best manage the trees in your community and more!
Issue link: https://read.dmtmag.com/i/22884
This Modesto ash (Fraxinus velutina) was pruned to achieve street, sidewalk, and building clearances while maintaining a full cano- py. Photo by Gordon Mann conference. I hope you will also take advantage of the A300 section of the SMA Website that will contain informa- tion on how to include the Standards in permit conditions, work conditions, specifications, ordinances, management plans, and master plans. And as always, I encourage the SMA membership to review the Standards during open review periods and discuss/send me comments. *** Writing Specifications for Pruning: In 2010, the Western Chapter ISA hosted four regional meetings in California and Hawaii to explain use of the A300 Standards to the membership. An attendee raised a question that illus- trates the uncertainty over how the Standards are meant to be used. She said, “The A300 Pruning Standards allow up to 25% of the foliage to be removed during a growing season. I have conifers that should not have more than 15% foliage removal in a season. How can I include the Standards and not over-prune my conifers?” The answer to her inquiry is that we cannot simply say, “Prune to ANSI A300 Standards.” All pruning should be performed to accomplish an objective. We have to write the specifications to meet our objective. The Standards www.urban-forestry.com These two trees had all “crossing” and “diseased” branches removed per vague crown cleaning specifications. Photo by David Lusk cover the full range and spectrum of pruning. The four methods—raise, thin, clean, and reduce—are not meant to be used in every tree pruning situation. The Standards have both “shall” and “should” language. Specifications are written with “shall” and “will” for reasons of measuring compliance (see example to follow). Cutting a branch from a tree creates a wound. We jus- tify our pruning actions by asserting that the benefit to the tree or tree owner is greater than the detriment created by the cut/wound. The objective is the reason we are pruning. Specifications written in compliance with ANSI A300 start with a clear objective, state which type(s) of pruning will be performed, the location in the tree crown where the work will be performed, the size of the branches to be removed, and the crown density to be removed from the subject tree. Since we cannot just say, “Prune to A300 Standards,” how can we write specifications? In the case of the workshop attendee, she could write the following: “The objective of this pruning project (contract or assignment) shall be light thinning of the designated conifers to achieve insect and disease suppression while 19