When the landscape crew is lacking sufficient training it is the tree that suffers. Weeds have encroached on the mulch area of this tree and an overzealous weed-wacker has repeatedly wounded the trunk of the Silver Buttonwood in the photo. The trunk has become girdled by the wounds and the tree will need to be replaced when it succumbs to the damage of being girdled. Nutrients in a tree flow up the secondary phloem right next to the cambium under the bark. Girdling results in the loss of the phloem and the cambium around the circumference of the tree depriving it of the structure necessary to support growth.