“”There was invasive plants encroaching on the land - this tells us a couple of things: carrying capacity is reduced, the BLM did not do their job in maintaining the range.””
And this is a problem with cattle especially when you bring in an outside feed source. Those seeds go right through and get deposited all over the place and have a nice nutrient environment to start out with. Most likely the cattle and the rancher are responsible for the invasive plants. Mesquites traveled at an amazing pace across Texas due to cattle.
yadayadayada - this land is designated for grazing - you know, cattle, sheep - those kinds of animals that eat and poop seeds. Deer do this also.
Proper range management is dealing with that, BLM’s job is range management, of which they rarely do a good job.
You asked me if I was merely speculating about reduced AUMs. I explained why it was a reasonable assumption - the carrying capacity is reduced by proliferation of noxious plants. the rancher is not getting full use of his permit, nor is he getting what he paid for.