Forestry expert witness Russell E. Carlson, RCA, BCMA, Tree Tech Consulting, writes on a residential boundary line tree dispute:
In general, boundary line trees are considered to be the property of both adjacent owners, and cannot be harmed without the consent of both. As to the tree on your mother’s property, the neighbor cannot cause direct harm by going on to her property.
The grey area is when the neighbor cuts roots. If he stays entirely on his property, he may have the right to do as he wishes. If he has a valid reason, such as building a pool or an addition to his house, and that causes injury, there may not be recourse. However, if his intent is to destroy the trees, and that can be documented and proven, the situation would probably be different. Again, this is very much dependent on the laws in your jurisdiction, and a lawyer is necessary to help sort it out.


