>>287024> I'll post it again because it's worthwhile contribution.
Oh, thanks! I'm glad you liked it.
I guess it would be very difficult to figure out what it looked like on the Great Plains that long ago. We only know what Europe looked like because we occasionally find pollen preserved in peat bogs which can be carbon dated, alongside the ocasional bog oak (https://en.wikipedia.org/wiki/Bog-wood
). Even then, it is a matter of debate how close the trees actually stood to the peat bog, exactly which species were there (some pollen preserves better than others), and how big the woodlands were which produced the trees.
The Great Plains don't really have any bogs where ancient trees and tree pollen could be preserved either, do they?
And yes, grassland is just a stage leading to what some ecologists call (or used to call, I'm running on decades-old info) a climax state. The Climax vegetation for most habitats in the termperate world consists of trees, which means that if you leave any piece of land for long enough it will turn into woodland. These days the term isn't used as much, as picking any one stage to call the "Climax" when the natural world is constantly changing is arbitrary, but it still holds true for most places that if you leave grassland for long enough, it will fill with coloniser species (aspen, birch, pine, and these days oak, amongst others). I've heard about the burnings practiced by indigenous people, which would make sense if you're trying to encourage new grass growth and kill off tree saplings.
I'm just guessing at this point, but could it be that the Great Plains were just too dry to support full forests like one finds on the coasts? Maybe it was covered in trees once, but excessive felling caused some kind of runaway effect where the environment became more and more hostile for trees to reproduce by themselves, and they slowly disappeared.
The more grassland that appeared, the more buffalo that would have appeared, which would have suppressed tree growth even further through grazing.