Two different problems
The first kind is mostly a nuisance and a trip hazard. Roots grow where there is water and air, usually just under the surface, and as they thicken they lift slabs. The second kind is an emergency. If soil rises on one side of the trunk, ground cracks open near the base, or the tree leans more than it did, the anchorage is failing. See windthrow.
To tell them apart, check the tree. Lifted paving with a steady tree is the first kind. A lean that is changing, or a mound of soil that wasn't there before, is the second.
Why it matters in Northern Nevada
Irrigated lawn trees keep roots near the surface, the same layer that sits under walks, curbs and driveways. Siberian elms, cottonwoods, silver maples and poplars are well known for shallow, aggressive roots. Frost also moves paving in our winters, so not every lifted slab is the tree's fault. See tree roots, sidewalks and sewer lines.
Be careful with the fix. Cutting a large root beside a walk can cost a tree its anchorage, and cheaper options, such as re-grading the walk, can be better.
What an arborist does about it
The arborist looks at which roots are involved and how big they are, and weighs pruning, re-routing paving, a barrier for the future, or removal of the tree. If you see lifting soil on a tree that stands near a house, keep people away and call; we answer seven days a week and the emergency line is 775.232.8243. If anyone is hurt, call 911. For a nuisance slab with a steady tree, the free estimate covers the options and the arborist will say which one protects the tree.
Sources
- International Society of Arboriculture, Trees Are Good: Recognizing Tree Risk (brochure) (read October 17, 2026)