What is a common method by which porcupines damage trees?

Chewing bark and leaves is a common method by which porcupines damage trees. Porcupines have strong teeth that allow them to gnaw through the bark, which can disrupt the tree's vascular system and ultimately lead to tree decline or death. This feeding behavior occurs primarily during the winter months when other food sources are scarce. By stripping the bark, porcupines can expose the wood and create wounds that may invite pathogens or insects, compounding the damage to the tree.

In contrast, girdling roots typically refers to roots being damaged by other means such as construction or pests, while breaking branches is not a primary behavior associated with porcupines. Eating fruits, while part of a porcupine's diet, does not cause the same level of damaging impact to trees as the chewing of bark, which is specifically aimed at obtaining nutrients found in the phloem.