Tree roots, rocky ground and falling limbs
Where there are trees there are roots, and a post hole that meets a large root may have to move a few inches or switch to a different tool. In the hills below the mountain, shallow limestone and chert can also turn up, which is hard on digging equipment and slows progress.
Mature hardwoods drop limbs in storms, and a fence line tucked under big trees takes more punishment than one in open ground. Cutting back overhanging branches before building helps, as does choosing a style that can shed a hit, such as chain link or open aluminum. Shade also keeps wood damp longer, so rot at the base of boards is a common worry in wooded corners.
