Scientists Say: Biodiversity

Biodiversity (noun, “By-oh-div-ER-sit-ee”)

Biodiversity describes the variety of species in a region. This includes all forms of plant, animal, fungi and microbial life.

Biologists estimate biodiversity a few different ways. One way is to count the number of species in a region. Scientists can also look at the members of a single species in a region. If the members of that species share similar genes, there is less diversity.

In general, biodiversity increases as you approach the equator. That’s because warm, wet climates allow more species to thrive. Tropical rainforests and coral reefs are near the equator. They are among the most diverse regions of the world.

The Amazon rainforest in South America is one of the planet’s most biodiverse places. It is home to about 10 percent of all the land-dwelling species on Earth. That’s about 3 million different kinds of life-forms! Yet the Amazon rainforest covers only half of a percent of the Earth’s surface.

Some places naturally support fewer species. For example, the chilly Arctic is home to only about 21,000 species. Its biodiversity is much lower than the Amazon’s.

Ecosystems with more biodiversity tend to be more stable. Why? Think of it like this. Say an area has many kinds of plants and pollinators. If one type of plant dies out, most local pollinators will still have many other plants to feed on. But in an ecosystem with less biodiversity, losing one species can spell disaster for others that rely on it.

Across the globe, biodiversity is decreasing. And the species that remain are losing numbers, too. One leading cause is human activity. People have destroyed many species’ habitats by turning land into roads, buildings and farms. Pollution, climate change and other human impacts have also played a role.

In a sentence

Human activity threatens the biodiversity of freshwater river fish in the Tonlé Sap Lake in Cambodia.

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