Taiga biomes have different elevations. Some parts can be mountainous and some parts steppe. The biggest factor of a Taiga biome is latitude. Most Taiga biomes are located in the high latitude countries of Russia, Canada (Taiga is called Boreal in Canada), and Scandinavian countries.
The taiga biome elevation is on the higher latitudes. This is because the temperatures are more conducive than in the lower latitudes. Another reason is that the taiga animals love cool areas. Read more details at http://kids.nceas.ucsb.edu/biomes/taiga.html.