I'm on the opposite side of the fence...I'm trying to encourage the forest to regrow! What has stopped regrowth of the forest in certain areas is grass. Not sure if this is what you're looking for though. I guess small amts of herbicide applied carefully might work but short of that...good luck! I find the more you cut the more likely you are to get weedy species....there'll always be something waiting to seed itself!

Heavy leaf matter or wood chips, perhaps call the local tree trimming company and ask for a truck load?

mow it down (either do it yourself or have someone come in with a tractor mower to do the job) and keep it mowed. it'll take some time to discourage all the natives that want to come in.... nature wants to fill empty spaces

Rental companies have a brush hog, walk behind brush mower with sharp blades

Wear good gloves, long pants & sleeves, heavy boots, hearing protection & be prepared to hold on tightly. It's a workout!

If you don't mulch the underbrush returns. Done it a few times to an area we're reclaiming as garden space along the driveway. Woods are tough!

We have a similar situation in our backyard. We have just rented 30 goats to be delivered some time this week. The cost to clear is much cheaper than hiring humans and there is the added benefit of not having all that weedy debris to dispose of afterwards.

The goat herd installs a temporary electric fence to keep the goats contained while they're clearing.

Elbow grease.
Pure, simple manual labor.

There's an upside- you can drop that gym membership.

Hand dig the saplings, mow everything, and in the fall, confiscate as many bags of leaves from the side of the road as you can find/transport. Dump those in the clearing and spread them. The thicker the layer of mulch, the better your weed suppression will be. Good luck.

Martha