Minecraft wiki entry for Shrubland, associated text: A biome with few trees and no tall grass. It is identical to the savanna biome. Along with swampland, it was one of the smallest biomes in the game, rarely ever being larger than a few chunks, and only spawns if the temperature is between 50% and 97%, and the rainfall value is below 35% and therefore too little to generate a forest. So, they were pretty useless.