Some of these areas are hurting from undergrazing. See here: https://www.ted.com/talks/allan_savory_how_to_fight_desertification_and_reverse_climate_change?language=en I saw this process work in parts of Arizona and the chacra in Paraguay. We killed off the big herds that the grasslands need to be healthy - but I'm not sure horses are the right answer either. They may eat too much etc.

Interesting, extremely readable look at a problem I had no idea existed. I like to think that the Judas horse understands exactly what it's doing.