English: "Unified Ecoregions of Alaska: 2001. This ecoregion map combines the Bailey and Omernik approach to ecoregion mapping in Alaska. The ecoregions were developed cooperatively by the U.S. Forest Service, National Park Service, U.S. Geological Survey, The Nature Conservancy, and personnel from many other agencies and private organizations."

Quoted from source (Metadata):

The Ecoregion units are arranged in two higher levels along
     gradients of climate, vegetation and disturbance processes.
     Thirty two ecoregions fit into eight groups at Level 2, and
     three regimes at Level 1 (Boreal, Maritime and Polar).
     Please refer to the tri-archy found on the back of the
     published map. Written descriptions are located in the
     section of Overview Description, following the individual
     ecoregional descriptions.
     Level 1 Level 2 Ecoregion
     Polar (-like)
                               Arctic Tundra
                                                               Beaufort Coastal Plain
                                                               Brooks Foothills
                                                               Brooks Range
                               Bering Tundra                   
                                                               Kotzebue Sound Lowlands
                                                               Seward Peninsula
                                                               Bering Sea Islands
     Boreal (-like)
                               Bering Taiga
                                                               Nulato Hills
                                                               Yukon-Kuskokwim Delta
                                                               Ahklun Mountains
                                                               Bristol Bay Lowlands
                               Intermontane Boreal     
                                                               Kobuk Ridges and Valleys
                                                               Ray Mountains
                                                               Davidson Mountains
                                                               Yukon-Old Crow Basin
                                                               North Ogilvie Mountains
                                                               Yukon-Tanana Uplands
                                                               Tanana-Kuskokwim Lowlands
                                                               Yukon River Lowlands
                                                               Kuskokwim Mountains
                               Alaska Range Transition
                                                               Lime Hills
                                                               Alaska Range
                                                               Cook Inlet Basin
                                                               Copper River Basin
     Maritime (-like)
                               Aleutian Meadows
                                                               Alaska Peninsula
                                                               Aleutian Islands
                               Coastal Rainforests
                                                               Alexander Archipelago
                                                               Boundary Ranges
                                                               Chugach-St. Elias Mountains
                                                               Gulf of Alaska Coast
                                                               Kodiak Island
                               Coast Mountains Transition
                                                               Wrangell Mountains
                                                               Kluane Range

end quote