Why is the arctic tundra classified as a biome?

Question

Here's a good definition of biome:

"Biomes are defined as 'the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment'" (Campbell).

http://www.ucmp.berkeley.edu/glossary/gloss5/biome/

The unique climate and vegetation qualifies the arctic tundra as a biome. Check the site linked above for a lot of information about the arctic biome.

thanks Ms. Sue