Biodiversity Definition: The Variety of Life Around Us

What is the meaning of biodiversity?

Think of biodiversity as a measure of how many different forms of life share a space and how different they are from one another. A rainforest with thousands of tree, insect and bird species has very high biodiversity. A huge field planted with only one crop has low biodiversity, even if it is full of plants.

An international treaty on the subject describes it as the variability among living organisms from all sources, including land, sea and freshwater systems, and covering diversity within species, between species and of ecosystems. In everyday talk, people simply mean the richness of life in an area.

The three levels in a biodiversity definition

1. Genetic diversity. Differences within one species. Rice comes in thousands of local varieties, and that variety helps some plants survive drought or disease.
2. Species diversity. The number of different species in a place and how evenly they are spread. A coral reef may hold hundreds of fish species.
3. Ecosystem diversity. The range of habitats in a region: forests, wetlands, grasslands, rivers, deserts, mangroves.

Scientists usually want all three. A region with many species but only one kind of habitat can still be fragile.

Why biodiversity matters

• Food. Bees and other pollinators help many crops set fruit, and wild relatives of crops carry useful genes.
• Medicine. Many medicines were first found in plants, fungi or microbes.
• Clean water and soil. Wetlands filter water; worms and fungi keep soil fertile.
• Stability. A varied ecosystem tends to recover better after fire, flood or pests than a simple one.

Scientists name the main threats as habitat loss, pollution, overfishing and overhunting, invasive species and climate change. Biodiversity loss is the term for a fall in variety, and extinction is its final step for any one species.

Example sentences

• The school garden was planted with native flowers to boost local biodiversity.
• Mangrove forests along the coast support a surprising amount of biodiversity.
• The report warned that draining the marsh would harm biodiversity for decades.
• Western Ghats forests are among the most biodiverse places in India.
• Our science project counted insect species to compare biodiversity in two parks.

How the word was born

Scientists used the two-word phrase biological diversity first. The short form biodiversity was coined around 1985 by an American scientist planning a national forum on the subject held in Washington in 1986. A book of papers from that forum, published in 1988, carried the new word in its title and spread it widely. The word took off further after the 1992 Earth Summit in Rio de Janeiro, where a global treaty on biological diversity was opened for countries to sign.

Biodiversity, ecosystem and environment

One handy picture: an ecosystem is the stage, and biodiversity is how large and varied the cast is. For more science vocabulary, visit the science and ideas section, and see how living things change over time on our adaptation page.

Tips for using the word

Biodiversity is normally uncountable, so say high biodiversity or a lot of biodiversity, not "many biodiversities". Common pairings include protect biodiversity, biodiversity hotspot (a region very rich in species that is also under threat), biodiversity loss and marine biodiversity. The adjective biodiverse works well in short writing: a biodiverse wetland.