I admit this analysis is off the cuff.
I think it could be helpful as a form of defense and protecting nature, but there’s the other side to the coin, which is, how do you then “hold nature accountable” for its “actions?” By that I mean natural disasters. For instance, if a mudslide occurs, how do you hold that mountain accountable? Do the victims of the mudslide then have the right to seek damages from that mountain? Could compensation come in the form of granting the victims the right to cut down all the trees on the other side of the mountain so that the timber can be harvested to compensate the victims for that natural disaster?
I think granting personhood is going to create issues from a legal standpoint and coming up with consistent precedents around agency and action. I’m not sure that this avenue of approach necessarily solves the problem at hand, which seems to be that we’re trying to prevent human beings from destroying the Earth. In that sense, it seems like the most effective and more direct response is to restrict the actions of humans rather than granting personhood to something else.