Creating Silvopasture Backwards

Everyone wants to plant trees in their pastures. I do too.

West Michigan z4-5, cold temperate, oak, maple, aspen types on my property

But more practically, what are good ways to create solid undergrowth in woods?
Thinning is the first step, but even in areas with plenty of light, the grass seems very weak. I guess the years of wood domination favor fungi?
Or maybe it just needs more time.

How would you turn hardwood forest (and I have a 5 acre witch hazel brushpatch) into productive silvopasture?

I would do what the old homesteaders did here in New England...use sheep. Granted it was a different time then when woolen mills were cranking and they needed sheep by the droves for their wool, but they still work well for clearing land.

For a lot of people, when they think of animals to clear land, they think of goats, but in many ways, sheep excel. First off they mob graze, meaning the tighter you pack them in, the more they will graze down your property to nothing. You might need some good fencing, but that is why they use sheep to graze rights-of-ways. Another great thing about them is that they love leaves of trees. When I was clearing land, I would fell my trees and let the sheep graze the leaves down, within a day the sheep would strip the leaves off an entire tree, at least as far as they could stand up on their hind legs and bite at them. And finally you might have an issue with poison ivy. The conditions you describe make it ripe for poison ivy...a sheeps favorite food. Yep no joke. I had a patch of it once...until my sheep found it and with their wool covered faces grazed it completely out of existence. Me, I was thankful, even the ER Dr did not want to touch my poison ivy face with his gloved hands! Yeah, it was that bad.

I honestly would consider sheep!

I was thinking about this a lot this morning. I think what I'd want to try is to raise browsers (goats, some breeds of sheep, deer) instead of grazers, and coppice a lot of the trees so they would put out growth closer to the ground, maybe cutting them knee to waist high, with some higher for hand cutting branches for browse and stick fuel. If I wanted some small meadows, I would cut the trees at ground level and mob with browsers (maybe also put some chickens and pigs in there if possible), then take them off and seed the clearings with native meadow species. I would rather have a mosaic of forest and small meadows than a few trees dotted around a big pasture, especially in a forest region or a prairie region which is reverting to forest (like mine is). Over a long period (generations) the meadows could be transitioned to forest and new meadows created. This way the regenerative and carbon sinking properties of forest could be maximized.