I'd say that the rainforest has the most, with a whopping 4 layers and thousands of species that inhabit it, to be honest. It's an amazing biome with so much space and the perfect atmosphere for plenty of animals.
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I would also say that the tundra has the least, because of it's harsh iciness.
<span>The tundra biome is the least diverse in terms of plant species of all land biomes. The rainforest is the most diverse in terms of plane species of all land biomes.</span>
