Answer:
Taiga
Step-by-step explanation:
The majority of Russia's region is extremely cold. To the point where it freeze the soil and make it hard for trees to grow on top of it.
Taiga is a type of biome with typically low temperature, But not low enough to freeze the soil. This make it possible for various types of trees to grow (such as pines, spruces, and larches ) . This is why Taiga is the most likely location for Lumber mills in Russia.