As an island leader you are allowed to change your island biome using /is biomes and the options you're allowed to choose from are Plains, Desert, Extreme Hills, Forest, Taiga, Swampland, Jungle, Birch Forest, Roofed Forest, Savanna & Mesa. I think that is pretty limited considering how many options there are for biomes too like a few that could be useful to change to are the following: Flower Forest, Mushroom Island, Cold Beach, Deep Ocean, River, and maybe even the Nether. Flower Forest is useful to get certain flowers to spawn that only spawn in that biome. I'm not sure what all the biomes may have that could give them benefits to adding but I'm sure at least 3 of those are worth it. I'll have to do my research on the rest.
