I don't think a gradual elimination of the norway maples is a viable strategy.Thinning them will only encourage the remaining trees to florish,outgrowing anything you are trying to establish near them.Your best bet is to clear them all out as soon as possible.You will achieve your ultimate goals far faster that way.Norway maples have a habit of suppressing the growth beneath them and destroying the ecosystems of the areas they invade.The first step in reestablishing those ecosystems is the complete elimination of that offensive weed.It's is even more imperitive if you live in a sensitive area to CLEAR THEM ALL OUT AS SOON AS POSSIBLE!

Sorry, I can't advise on your particular soil/conditions but NYWoodsman is correct that the norway maples have got to go.

This is a picture of a norway maple I girdled 16 months ago.The tree leafed out normaly last spring but by the end of the summer its canopy had withered and the base sprouted suckers(browse away)below the chiseling.I think it's completely dead and I don't expect it to produce leaves this spring.So as not to cause any unnecessary disturbances, I will leave it to rot in place.It was one of about two dozen problem weed trees I dealt with in an afternoon. {{gwi:1352236}}

This is the ravine that the norway maples were invading.The ecosystem had been disturbed by the chestnut blight which killed all the large chestnut trees about 70 years ago.They were all still standing when I moved here.Next it appears a fire had swepted thru the area 20 years later killing some of the large oaks and clearing the woods of the understory in some areas.Finally the invasion of non-natives and overbrowsing by deer had definately put the ecosystem in decline.I've just fenced in the area to keep out the deer and hope to replant the species that appear absent.My model for a healthy ecosystem and the scource for those plants being the similar ravines in the area that are less disturbed. {{gwi:1352238}}

I can reccommend plenty of natives that can take shade or sun. The sandy soil is the part I'm not sure about as I don't have much sand in my soil. Spice Bush can handle shade as can various native cherry trees and viburnums. Mountain laurels can handle partial shade and are very attractive. I have some very young white pines that are doing well in partial shade now and some volunteer native hollies that are thriving in a wet area that is very shady. Red osier dogwood and native willows might be good for holding a slope together. Live willow stakes are often used for erosion control on slopes. Native sumacs might work well in the sunnier portions of your slope. Here is one web address that can put you in the right direction: http://www.ct-botanical-society.org/garden/garden2.html. Ernst Conservation Seeds (based in PA) also has a great catalog that helps you figure out what might work where. A native nursery closer to your region would also be a good bet.
NYWoodsman, you have great pictures. Time to publish your own coffee table book.

Thanks bob,but I can't claim much credit, all I gotta do is point the damn camera out the front door.This place is that nice.But the amazing about it is when I tried to sell it a few years ago,in a moment of insanity,I found it to be almost unmarketable.Two small cottages down the end of a dirt road,something about it not having enough bathrooms..or maybe too far from the er.

Hi nywoodsman & bob64 - much good advice here - thank you kindly! I didn't think I could pull the dreaded NM out, but it turns out its the one tree you can kill here!

Now I have a new set of questions:
If I pull up the smaller trees, and girdle the larger ones, how many months/years before they're under control (i.e. not throwing up suckers/new plants)? If I girdle the larger trees right now will they put out leaves next summer?

Can I plant replacements right away, and how long do you think they'll take to establish once the NM are eradicated?

Thanks again for your input.

I've girdled some NM's and there were never suckers but new branches did pop up below the girdling. A girdled NM might put out leaves once or twice post girdling. Make sure you completely remove the cambium layer in the area you girdle to increase odds of success. Some folks also apply herbicide on the girdled area immediately after girdling. Your bigger problem is that once all that new light comes in there will be some germination of NM seeds that are already laying around in your soil. I would probably try to put in the replacement plants soon after killing off your current crop of NM's but start with some cheaper stuff to keep costs down since you can't know in advance how it will work out. NYWoodsman might have more to say on how long it takes the soil to detox from NM - I tend to be impatient. Give your new plants some extra care and dilligently weed out any new NM's and you'll probably be o.k.

If you girdle the Norway Maples this winter/spring, they will still leaf out and look almost normal this summer - 2007. Next year - 2008 -they might partially leaf out but will probably not make it through the whole summer. So I think that means you should plan on planting the most heavily norway mapled areas not until summer '08 or even summer '09. However, there are probably some spots that are not in really dense maple shade that you could start to plant now. If you're like most of us do-it-yourselfers you probably wouldn't get it all planted until long after summer '09 anyway.

For shade and deer I think Spicebush is nice for moister areas. Mountain Laurel is versatile and has good winter interest, but will be browsed by deer. There are many viburnums, and Mapleleaf viburnum might be the best choice for a woodland. Don't count out Juneberry just because your neighbor had problems. If the neighbor's plants were under Norway Maples (or under native maples, or some other trees) that might have caused them to fail. Also, some percentage of plants tend to fail even with proper planting and care, so a single failure doesn't mean the plant species isn't suitable for the ravine.

I wouldn't worry too much about the sandy soil. I live in an area where some soils are almost pure sand and other have lots of clay and many of the same plants occur in both areas.

Oops, I spoke too soon. Ravine by-laws state that you must apply for a permit to cut down or girdle ANY tree. Involves calling in a certified arborist, with a report then going to the city forestry division, followed by a site visit.

They suggest taking invasive trees out in phases, similar to my original post.

Quite frustrating that the by-laws are setup in a way to make it inconvenient and expensive to do the right thing. Especially considering that there are numerous flyers extolling the danger of foreign invasives, and the necessity to aggressively remove them...

I guess I'll try calling the city forestry dept. again and see what they say.

I have sand/powder-clay soil and full shade of mostly sugar maples(water hogs) but also black cherry and Beech.

For shrubs I have the following:

Serviceberry
Elderberry
Alternate Leaf Dogwood
Silky Dogwood
Spicebush
Winterberry
Ninebark
Nannyberry
Highbush Cranberry
Arrow Wood Viburnum
Witch Hazel

All are growing and thriving in deep shade, sandy/powder-clay soil aka dry as a bone.

Barb
southern Ontario, CANADA

I have read this thread with great interest. I have a mostly wooded lot with sandy loam that is well-drained and can get pretty dry. I also have some mature Norway Maples and about a million Norway saplings that I want to remove/girdle.

I am currently marking the Norway Maples and Oriental bittersweet vines with flourescent orange spray paint. A friend is going to bring his chainsaw to cut down the saplings and girdle a couple of the mature norways, as well as cut the vines (to which I will apply a herbicide).

I spoke to someone at a NH nursery who said that the best technique to girdle the maples is to make TWO 1-2 inch deep cuts with the chain saw all around the base of the Norway maples. He also said that the best time of year to do the girdling is mid- to late-summer because that is when the least energy and nutrients are stored in the roots, which reduces the chance of root sprouting after the girdling.

Nywoodsman, I would love to see the photos of your results if that is possible - you can email me if you read this.

Barb, that is so encouraging to read that your shrubs are doing well in dry shade. Many of those species prefer moist soil, so I've read. Do you get much flowering in the deep shade?

terrene, I 'do' water the shrubs for the first 2 years until they are established but after that they are on their own. I cut the bottoms off 2L pop bottles and water right into the root area. I've been told that this style of watering can cause the maples to choke the shrubs with their fibrous roots but everything is doing just fine. As for flowering, no they do not flower the way they would if they had more sun but I get enough berries on all the shrubs to allow the birds a few days of munching from each species. The species that are meant for shade do well with flowering and fruiting.

Barb
Southern Ontario, CANADA