After a certain amount of time has passed, what was once "invasive" becomes part of the environment.  120 years is pretty long time for tge cattle to have been there. Nature adapts one way or another. Sometimes the invasive species survives and thrives in its new environment or it eventually will die off because it was not meant to be there. Nature has a way of taking care of its self except when it comes to the most invasive species of all, humans. You have some who can live in harmony and the others who end up destroying the land and/or the plants, trees,birds and animals. Eventually, Nature will survive as the invasive will adapt or end up killing its self off by killing everything it  has devoured .