User blog comment:Gen. Grievous1138/On the new biomes/@comment-25101089-20151212220148/@comment-25869554-20151213174442

Yeah, it's a complicated thing to define. But certainly, every biome that extends LOTRBiome should have their own page. If there are more than one 'tier' of extension, then maybe the second tier as well. For example, both Mordor and Nurn (a sub-biome) should have pages, but the third tier (Nurn Marshes in this example) shouldn't. That would then include most of the sub-biomes you mentioned, because they have sub-sub-biomes.