You need to know a little bit about where you will be operating, what kinds of trees are there, and how tall they are. Or, rather, how tall their limbs are.
As a general rule, at low elevation like 6000 feet, pine trees can grow pretty tall, and their first usable limbs might be 15 feet up. That varies a lot. As you get up closer to timber line (maybe 10,000 feet in Yosemite), the trees are shorter and their usable limbs are closer to the ground and a lot less usable.
In Alaska, the grizzly bears will simply eat the tree trunk.