I'm not sure about this specific area, but it seems to me that there's a case to be made that bison probably over-grazed when they were present. I am working on getting a healthy plot of native grasses, and I know that burning or cutting them at times can promote their root systems, and keep out invasive species.
Have you ever heard of a book called "Braiding Sweetgrass" by Robin Wall Kimmerer? I really recommend it, it's more philosophical than it is scientific, but man, it's philosophy that everyone could use. Wholesome, neighborly, compassionate philosophy. It's quite good. There's a chapter in there, where she talks about a study she did with one of her students. They were looking at a type of grass, I can't remember what kind (though it might actually be sweetgrass), and they had three different groups. The first group, they left untouched. The second group, they'd harvest bits here and there by cutting out the grass. The third group, they'd harvest bits here and there by pulling the grass out by the roots. What they found was, the grass that was left alone, didn't grow so well overtime. The other two groups of grass though? Flourished. And you're right, prairies and forests often depend on wildfires to kind of reset them and facilitate growth. Unfortunately, due to global warming, some of these fires burn so hot now that they've become truly destructive, and instead of facilitating growth, they impede it.