Brian, sorry for being a wise ass, although cedars do in fact make great fence posts.
The subject of invasive species is complicated, at least for me. Is it bad if a non native moves in and upsets the eco system? Yes it certainly can be. Unless your a cow in the Sand Hills and there isn't another tree that can live thru the harsh winters, and you wouldn't either without the benefit of a wind break. I'm sure the ranchers who use cedars for wind breaks for their homesteads and livestock will tell you they are happy they've found something that can survive and help fight the nasty north wind. At the same time, it's a bad thing that the cedars can take over the river eco system if left unchecked. So, I guess my feelings is they should be managed, but I'm not about to say that all non native species should be eliminated because then we'd have no golf courses in the sand hills, or at least golf courses as we know them.