The area of United States which is similar to the southwestern caucasus forest region of Russia is the southern Appalachia region of the United States.
Step-by-step explanation:
The reason why these two regions is similar is the warm temperate tertiary in both the regions. The other similarities also include the species-to-genus, the florist composition and the species-to-families.
But both the regions have different history of development and the differences also include taxonomic diversity and the percentage of trees.