It makes good sense to pick out the strongest one or two and cut the rest if you want a lawn type setting.

How large are these maples? Big mature trees will fill in more slowly. Sometimes if you eliminate all but one tree in the forest it's roots get damaged by the equipment, it is not ready to face the wind load alone and I think there may be the posibility a sun scald issue also if it goes from living in shade to a full sunny yard too quick.

What type of maples? If you have a mix of Norway and Red, I'd cull the Norways first since they're invasive.

IME exposing trees that have been in a cluster to wind load often results in the winter weather or microbursts topping them as Toronado mentioned. I'd probably cut half in the moss and multiflora areas and not rethin for a number of years. Maples resprout vigorously, so paint the outside margin of the cut surface with a brush killer (and do the cutting and brush killer also with the multiflora as well.) In the rhody & holly area, I'd plant the broad leafed evergreens at the margins since the maples will create a great deal root and sun competition and won't grow well. Norways should be the first culled and it that's all you have, replaced over time.

how about some pix .. ken

Great advice from all of you. Thank you very much. I hadn't considered vulnerability to wind at all. It makes sense to thin over a number of years. I have assumed the maples are all sugar maples, but will double check that they're not Norways with an id. Mad gallica, you have me really concerned about the ravine. I thought the ferns would be a good choice because it is a channel for snowmelt and water runoff. I've seen ferns grow into a dense groundcover that eliminated weeding. I've already started planting them in the "channel" at the base of this slope, where it is a dry stream bed leading to a stream for most of the year, and they are thriving. I will work at those multifloras and other invasives, and leave as much shade as possible. You really think it's hopeless? What would you do instead? Elsewhere I'm putting in pachysandra. The goal is to have a neat lush look but not to mow or weedwhack, even once a year. I had considered daylilies in the ravine but this is not fenced for deer.

There are ferns that form a dense ground cover ferns in my well-drained areas - they spread and are about 2 1/2 feet tall. Check out Dennstaedtia punctilobula, hay-scented fern.

i was given some hay-scented ferns and planted them near the ostrich and was impressed with how much better they fared in sun and drought. And now that I think about it, they also run like a mat while the ostriches clump. It seems that best time to transplant is in the spring.

need pictures. if it is silver maple you must spray with herbicide.

Let me put it this way. I occasionally get multiflora coming up in the phragmite swamp. If they can get a purchase there, they can get started anywhere. The area is going to require periodic weeding pretty much no matter what you do. It is not going to be maintenance free, and depending on the size, may take a good days work once a year.

Also be aware if you use glyphosate on the maple stumps some of the trees may have their roots welded together and will then kill others that you may have wanted to save. Not sure how often this happens but I killed a second Manitoba Maple this way buy drilling holes around the outside of a 1 foot stump and applied full strength Roundup a couple of times. A tree about 15 feet away was killed dead.

Thanks for the warning, Wayne. I won't use it unless there are no other trees around. Now I wonder if that's why a maple died near a lot of ailanthus stumps I applied it to. Madgallica, I have the multiflora coming up in a stream too. And a shady slope that's dry a bone! What a plant..

"I wonder if that's why a maple died near a lot of ailanthus stumps I applied it to."

You wouldn't think so with the two different species but I wouldn't put it past the realm of possibility I suppose.

FWIW, I rather like silver maples in the right spot.

downsides outweigh the good things, just like the case of callery pear.