Greetings Chris:
In attempt to hasten the encroachment of woody vegetation (shrubs & trees) on areas managed for grasses and forbs, land managers often utilize the resources of chainsaws and brush mowers. To keep woody vegetation in check, land managers will utilize chainsaws either to fall trees or to girdle trees in place to promote various sized wildlife snags. These snags provide foraging opportunities, perches, nesting sites, and cavities for countless wildlife. Therefore, girdling woody vegetation is just one of many techniques that land managers utilize to hasten woody vegetation encroachment and to maintain the presence of vertical structure.