Trees mother planted on neighbors property

[Mont]

25 years ago,when my mother moved into the house she currently lives in, she planted some trees on the neighbors property, WITH his permission, as a windbreak. Now he occasionally indicates he might cut the trees down. This would be devastating to my 75-year-old mother. Is there any chance that she would have any right to prevent this, considering she planted the trees and took care of them all these years? This is in the state of Montana. The trees are one line along the border, not in any way interfering with the neighbors usage of the property.