ISA Certified Arborist Practice Exam 2025 - Free ISA Arborist Practice Questions and Study Guide

Tree girdling refers specifically to the practice of removing a strip of bark from around the trunk of a tree. This action disrupts the flow of water and nutrients from the roots to the leaves, as the vascular cambium, which is essential for the tree's growth, is located just under the bark. Girdling can lead to the tree's decline and potentially death if performed excessively or improperly, and it is often used in forest management or as a method of killing undesirable trees without felling them.

In contrast, the other choices represent different practices that do not relate to girdling. Wrapping trees to protect them from animals is a preventive measure, the application of fertilizer pertains to enhancing growth, and pruning involves trimming branches for shape and health rather than removing bark. Thus, the definition of tree girdling aligns solely with the removal of bark, making it the correct answer.