The Timber Pines are specific trees that are located in the northern part of the map that, when cut down, will roll and cause damage to enemies in their path. These trees have particularly thick trunks and are covered in green pine needles, though they shouldn’t be confused for the smaller pine trees that are covered in snow in the same area.

To find these trees, you’ll want to navigate to the snowy section of the map in the northwest corner, above Logjam Lotus.

Source: https://www.distractify.com/p/what-are-timber-pines-in-fortnite