Try Tamarack (Larix laricina), black spruce (picea mariana) and google
willows (Salix sp.).
For a ground cover, use wild mint(Mentha arvensis) or fireweek
(Epilobium angustifolium). Tuck in a few pitcher plants (Saracena
purpurea) to control mosquitoes.

Here's a site that might offer more ideas:
http://www.unep-wcmc.org/sites/wh/grosmorn.html