Pine Barrens (An Endangered Ecosystem)

Also known as pine plains, sand plains, or pinelands (or more locally in Albany NY, the Pine Bush), these are sandy ecosystems with sparse scraggly pine trees, they are incredibly important, and quite endangered. One of the reasons these ecosystems are so threatened is due to a lack of awareness.

These are ecosystems that grow along the east coast of the U.S. meaning they can grow in hot and cold climates (which might make them really great for transitionary biomes. And depending on how complex you want to make them, they can be constructed with features and land forms that already exist. In minecraft it would be kind of like a plains or a savanna biome, with a bit of coarse dirt or sand, and pine trees (and baby oak trees), and they could be colder or warmer, with snow or without.

Color wise you could add in more earth tones, like you have previously with the savanna and/or mesa, into this biome. The Biome could have a more autumnal feel to it without it feeling out of place or strange within the biome itself. 

That said in gameplay they could function a few ways. One of course giving a variety to the biomes that are friendly to builders, with larger open areas. Another being that they can function as a sort of transitionary biome between climates, and really furnish the world with a new look, made out of older stuff.