What TO do under ugly trees?

OK, so I know NOT to plant under mature trees. But what DO I do? I have mature silver maple (not my choice), 9 black walnuts (again, not my choice), pecan, hickory, and fruit trees. All have incredibly ugly tufts of fescue (did I mention, NOT my doing), mulberry, box elder, honeysuckle, etc. growing underneath them. I need reasonable ideas for dealing with this, short of cutting them down. I have more than an acre to mow, with horses that "mow" another 4 or 5. I moved here less than 5 years ago, and with a single teacher salary, improvements are slow. My goal is to have at least 70% Missouri natives in this one acre area. Any ideas?

Thanks so much!