Which ecosystem contains about half of Earth's plant and animal species?

• A. Deserts
• B. Coral reefs
• C. Rain forests
• D. Tundra

Answer: (C)

Biodiversity concentration in tropical rainforests comes from a combination of stable, warm temperatures and abundant year-round rainfall, which create a vast number of niches. The forest’s layered structure—emergent trees, the high canopy, understory, and forest floor—offers many distinct habitats, allowing an enormous variety of plants, insects, birds, mammals, fungi, and other organisms to coexist in a relatively small area. Because of this multitude of niches and the high productivity, tropical rainforests are estimated to harbor about half of the world’s plant and animal species, even though they occupy only a small portion of Earth's land surface. Deserts and tundra are far less diverse due to harsher conditions that limit the number of species, while coral reefs are highly diverse in the oceans but do not account for half of the planet’s plant and animal species overall.