Which biome has the greatest diversity of species?

• A. Tropical rainforest
• B. Desert
• C. Tundra
• D. Savanna

Answer: (A)

Biological diversity is highest where the environment is stable, resource-rich, and offers many distinct habitats. Tropical rainforests fit this pattern: warm, wet conditions year-round support continuous growth and an enormous variety of life. The forest’s multiple layers—emergent trees, a tall canopy, an understory, and a forest floor—create a wide array of habitats, giving many different places for species to live and specialize. This combination of high productivity and structural complexity leads to a very large number of species, from insects and plants to birds and mammals.

Deserts, tundras, and savannas each present harsher conditions or more limited resources, which reduces the number of niches and the variety of life they can support. Deserts have extreme temperatures and scarce water; tundras have cold, with a short growing season and simple plant communities; savannas have seasonal resources and fewer tree species. These factors mean fewer species overall, so they don’t reach the same level of biodiversity as tropical rainforests.