This practice of shaping trees to communicate information was common throughout pre-Columbian North America. Please point out examples of this practice outside of North America in the comments if you are aware of any.
To mark trails, river crossings, or important sites such as Pikes Peak in Colorado, Native Americans would bend young trees into shapes that were not found in nature, such as right angles. Once moulded, saplings would retain these unusual shapes throughout their lives.From here.
John Anderson pointing out a Ute Indian burial tree. The section coming up from the ground represents birth, the horizontal section represents a walk through life and the section rising up to the sky represents returning to the heavens (death). (Thank you in advance Bob Falcone and Cara DeGette for honoring this claim of fair use for scientific and educational purposes without profit).
[M]any CMTs in Park and Teller Counties point toward Pikes Peak which held spiritual significance to Utes — others point towards what we now refer to as Ute Pass. And some of the trees point towards constellations while others show relation to seasonal solstices and equinoxes.
From the Colorado Springs Independent citing John Wesley Anderson, a retired engineer, former El Paso County Sheriff, and researcher working closely with current Ute Tribal leaders (one of the main tribes in Colorado today and at the earliest attested post-Columbian times).
Pike's Peak, Colorado via Wikipedia.
A spiral juniper tree at Deadhorse Point State Park near Moab, Utah. Stock Images.
Zaleski State Forest, Ohio. Knowandtell CC BY-SA 3.0
Jasper, Georgia, USA. Wasrts CC BY-SA 3.0