map is looking good. i think the colors of the regions look fine except for the "Plateau" because it is so small - took me a while to find it. I would try switching it with one of the brighter colors on the map to make it stand out more.
my only other gripe is using "Dine" instead of Navajo. i realize that they call themselves Dine (with an acute accent over the E, actually) in their language, but this map is in English and that tribe is widely recognized as Navajo (which they also use to refer to themselves). I appreciate the need for space-savers, but I blinked at the map for a couple minutes in shock at their exclusion before I finally made the connection. i think you're better off cutting into the extra space in Nemene and change it back to Navajo.
i disagree with Pamoa's suggestion for geographic names rather than compass regions, but some suggestions if you go that route:
NW = Coast Mountains
NE Woodlands = Great Lakes
SW = Desert lowlands?
SE = ? Swamps ?
as for Artic & Sub-Artic, how about Artic & Tundra?
Lastly - the trees should definitely
be pine trees that far north (the current trees looks deciduous) and there really shouldn't be ANY
trees in the Artic.