Unfortunately, no. From what I've found, forest graphics are region specific, not biome. Such as "Asia" or "America". (Generally the different colourations you see on trees and tiles depending on where you have settled).I suppose it isn't possible to have snow on forests in tundra? We've seen snow-capped foests in Civ VI so far, and then there's also this ancient thread: http://forums.civfanatics.com/showthread.php?t=470452 It seems it hasn't come to any conclusion, though.
I don't know for a fact, but I don't believe that this could be coded in either.
