Great question. Just to throw my two cents in... also to agree with much of what was said already... when one person says something, it may sound good, but when others say the same thing, it sinks in
Acer negundo (Boxelder)
- Common tree east of the Rockies
- Likes wet soil, so if you have a lot of them... maybe you are in a flood plain? maybe you have a low water table? maybe you are where a river or stream used to run? maybe your wood lot is where a pond used to be? I would seriously consider running some contour lines on your property... I wouldn't be surprised if your wood lot is in a low spot.
- In the Maple family, so yes, it has sap that cam be made into syrup. I agree with Ian, the sap has less sugar content, so it takes more sap to produce the same sweetness of syrup than a Sugar Maple; however, with more concentration comes more flavor. Also, you can just use the sap as a drink in its own right... a lightly sweet beverage.
- Wood is soft, light, and weak. Not good for construction, but not too bad for cheap, short-lived applications... like boxes (hence the name!)
- Since the wood is weak, it will not hold up well in strong wind storms or ice storms (you're in MN!)
- Bonfires are an okay use, but boxelder is really not a great firewood.
- The tree produces seeds that birds and squirrels like; deer will eat the browse (new growth of young sprouted plants/trees)
- In the Great Plains and other farming communities, Boxelders are great cover plants (trees) in shelterbelts for deer and cattle
It sounds like you don't have a lot of land... if you did, I would say keep them and let them be part of your Zone 4/5. But you don't have acres upon acres... so...
1) I would chop them down and use them to make small hugelkultur beds (real hugelkultur beds are massive... 6-10 feet high) on contour... under a swale on contour in your yard if this is possible.
2) I would consider keeping a couple of the larger trees for wildlife attraction. The birds will eat the insects that love the deep furrowed bark, and the birds will eat the seeds, and some of the birds will fly into your garden and eat insects, and more birds will attract other wildlife and increase your biodiversity in general. Also, the trees will attract squirrels. This again increases biodiversity, and this might not be too popular, but squirrels are good food and easily taken with a pellet gun or a .22
3) The few large trees that you keep will produce a large amount of biomass each year in leaves. Great for compost. Great for deep mulch in a chicken run.
4) The few large trees can produce quite a bit of sap to make a little syrup each year (check out TapMyTrees.com)
5) Consider trimming back the tree and growing something like Hardy Kiwi up some of the trees
6) The branches that fall each year from snow and ice can be chopped up and used in compost or as kindling - since it burns fast
7) Getting rid of these trees will open up the canopy and let more light it. This will allow you to maybe create a bit more of a patchy meadow effect instead of a wood lot. Then you can plant some more useful trees like dwarf fruits or nuts in their place. This will also allow you to plant some more herbaceous plants that desire a bit more sun - brambles and gooseberries and currents considering your location.
8. Getting rid of these trees will reduce the chance that the next ice storm will not knock the tree over and onto your house or fence or newly planted trees.
Just some thoughts off the top of my head.
Hope that helps! Have fun!