Why Variety Keeps Ecosystems Strong

By the end of this lesson, you will be able to describe how biodiversity helps an ecosystem stay stable and keeps the organisms living there healthy.

Biodiversity means the variety of different living things found in one place, including different kinds of plants, animals, fungi, and microscopic organisms. An ecosystem, which is all the living things in an area plus the nonliving parts like water, soil, and air, works best when it has a lot of biodiversity. Think of it like a safety net woven from many threads. If one thread snaps, the rest still hold. If the net is made of only two or three threads, one break can make the whole thing fall apart.

Picture a Texas prairie outside your town. It might have big bluestem grass, wildflowers, prickly pear, grasshoppers, meadowlarks, coyotes, mice, and countless soil bacteria. Suppose a long drought kills most of one grass species. Because other deep-rooted plants survive, the soil stays anchored, the grasshoppers still find food, and the birds that eat grasshoppers still find meals. The prairie bends but does not break. Now imagine a field planted with only one type of grass. One drought, one disease, or one insect outbreak could wipe out everything that depends on it.

Biodiversity also keeps individual organisms healthier. Many different plants mean a more balanced diet for grazers. Many predators and parasites keep any single pest species from exploding in number and spreading disease. Different plants and microbes recycle nutrients in different ways, which keeps soil rich so the whole food web stays fed. This ability of an ecosystem to keep working over a long time is called sustainability.

Try it: If a disease killed every mesquite tree in a Texas ecosystem, explain in your own words why an area with many other tree and shrub species would recover better than an area where mesquite was the only woody plant.