Q: Our neighbor’s large oak tree fell over and uprooted during a violent rainstorm while they were out of town. How common is it for an apparently healthy large tree to fall over?

A: It’s a truism that well-anchored trees rarely fall over. Trees, as they grow, sense when and where to produce anchor roots. These structural roots bind to the soil, anchoring the tree so it can grow tall and withstand wind and water loads. But anchor roots can be severely damaged by careless installation of driveways, sidewalks, or plumbing lines. The tree can appear healthy if its feeder roots are active but once the anchor roots are gone the tree is living on borrowed time since anchor roots rarely regenerate. If any kind of trenching is done inside a tree’s drip line a certified arborist should be hired to evaluate plans and to suggest techniques that minimize damage to anchor roots.