Biodiversity and Conservation

What is biodiversity?

Biodiversity is short for "biological diversity" — the variety of all living things on Earth. It is more than just a long list of species. Scientists measure biodiversity at three levels:

• Genetic diversity — the variety of genes within a single species. This is why no two individuals (except identical twins) are exactly alike, and it helps a species adapt to change.
• Species diversity — the number and variety of different species in an area.
• Ecosystem diversity — the range of different habitats, from coral reefs to rainforests to deserts.

Earth is home to an estimated 8 million or more species, and we have formally described fewer than a quarter of them. Biodiversity is the living wealth of the planet.

Why biodiversity matters

It is tempting to think some species "don't matter." In reality, every species plays a role, and variety itself brings strength.

Stability and resilience. A diverse ecosystem is like a team with many skills. If one species declines, another can often take over its role, so the system keeps working. Low-diversity systems are fragile — a single disease or drought can collapse them.

Ecosystem services. Nature provides benefits we depend on, called ecosystem services:

• Pollination of crops by insects — about three-quarters of food crops rely partly on animal pollinators.
• Clean water filtered by wetlands and forests.
• Climate regulation, as forests and oceans absorb carbon dioxide.
• Soil formation and nutrient cycling.
• Medicines — many drugs are derived from wild plants, fungi and microbes.

To understand how species depend on one another, it helps to revisit how energy and nutrients flow through food chains and ecosystems.

Threats to biodiversity

Scientists warn that species are now going extinct far faster than the natural background rate — fast enough that some researchers call it a "sixth mass extinction." The main human-driven threats are often remembered as HIPPO:

• H – Habitat loss: Clearing forests, draining wetlands and converting land to farms or cities destroys the places species live. This is the single biggest threat.
• I – Invasive species: Species introduced to new areas can outcompete or prey on native ones that have no defences.
• P – Pollution: Plastics, pesticides, excess fertiliser and chemicals harm wildlife and disrupt food chains.
• P – Population (human) and overexploitation: Overfishing, overhunting and over-harvesting remove species faster than they can recover.
• O – Overarching climate change: Shifting temperatures and rainfall force species to move, adapt or die. Many cannot keep up.

These threats interact and amplify one another. You can read more about the warming planet in climate and weather.

What conservation does

Conservation is the protection and careful management of nature so that biodiversity survives. It works on several fronts:

Protected areas (in-situ conservation). National parks, marine reserves and nature reserves protect species in their natural homes. Roughly 17% of land and 8% of oceans are currently under some protection, and many nations have pledged to reach 30% by 2030.

Ex-situ conservation. Zoos, botanical gardens and seed banks safeguard species outside their habitat. The Svalbard Global Seed Vault, for example, stores millions of crop seeds as a backup.

Habitat restoration. Replanting forests, rewetting peatlands and reintroducing lost species (such as beavers or wolves) can rebuild damaged ecosystems.

Laws and agreements. International treaties like CITES restrict trade in endangered species, while national laws protect habitats and ban harmful practices.

Sustainable use. Conservation is not only about "hands off." Sustainable fishing, farming and forestry let people use resources without destroying them.

The role of individuals

Big change comes from governments and industry, but individual choices add up: reducing waste, supporting sustainable products, protecting local green spaces, and pressing decision-makers for stronger protections all matter.

Try it yourself: a biodiversity survey

You can measure biodiversity in your own neighbourhood.

1. Choose a small area — a corner of a garden, a patch of park, or a window box.
2. Mark out a square metre using string or sticks (this is called a quadrat).
3. Over 15 minutes, record every different type of plant and animal you can find inside it. Use a simple field guide or identification app to name them.
4. Count the number of different species (this is the species richness).
5. Repeat in a second, different location — for example a mown lawn versus a wild meadow edge.

Compare the two sites. Which had more species, and why might that be? You have just carried out the same kind of survey ecologists use to monitor the health of ecosystems and the success of conservation.