What it is and how it holds
A tree's anchorage is not a tap root, as people often think, but a wide, shallow plate of structural roots and the soil bound between them, a disc rather than an anchor. When wind pushes the crown, the plate resists on the downwind side by its weight and the strength of its roots, and on the upwind side the roots pull. If roots are cut, rotted or constricted, or the soil is saturated, the plate can tilt or lift.
The size of the plate depends on the species, the soil and the space, and its edges are not the drip line. See structural root zone.
Why it matters in Northern Nevada
Trees on irrigated lawns, on filled lots, near trenches, or beside a basement dig lose part of their plate. Add a wet winter and a Zephyr gust and the tree may go over. Signs to check include soil heaving on one side, cracks in the lawn or paving radiating from the base, and a trunk that has begun to lean. See windthrow and root heave.
If you see lifting soil on a tree near a house, treat it as urgent and keep people away.
What an arborist does about it
The arborist looks at the soil around the base, the condition of the root flare, the evidence of cut or decayed roots, the lean and the crown's weight, and decides whether the tree can be supported, lightened or must be removed. A tree that is lifting is not a pruning job. The right step is to call; we answer seven days a week, and the 24-hour emergency line is 775.232.8243. If anyone is hurt, call 911 first.
Sources
- International Society of Arboriculture, Trees Are Good: Recognizing Tree Risk (brochure) (read October 17, 2026)