Hi - my name is XXXXX XXXXX I'm a Real Estate litigation attorney here to assist you.
If the trees are on your property, easement or no easement, your neighbor cannot come onto your property and cut a limb or branch off of the tree. If she were to come onto your property and cut your trees, or any part of them, you could file trespassing and destruction of property charges against the neighbor.
Also, if there is an easement on the property, the easement is only available for use by the person or entity that holds the easement. Thus, the easement would not give her any right to do anything.
The first thing to do is to get the property line marked. Usually, the county tax office will come out and do this free of charge. You can also contact a surveyor to mark the line for a fee. As long as the trees are on your property, she cannot do anything to them.
However, if any part of the trees extend onto her property, she would have a right to cut the trees back to the property line.