Biodiversity

Biodiversity is the variety of life on Earth. It includes the differences between plants, animals, fungi, and other living things, as well as the way they live together in groups called ecosystems. This variety can be seen in genes, in the number of different species, and in the different kinds of ecosystems.

The world is not the same everywhere in terms of life. Places near the equator, called the tropics, have the most variety because they are warm and have lots of food for living things to grow. Tropical forests cover a small part of the land but hold about half of all the world's species.

Life on Earth has not always been this way. Over time, there have been times when many species suddenly disappeared. These are called mass extinctions. One big change happened during the Cambrian explosion, when many new kinds of animals first appeared. But later, huge losses happened too, like the Permian–Triassic extinction, which was the worst and took a long time for animals to recover from.

Today, human actions are causing many plants and animals to disappear. This is called the sixth mass extinction. Cutting down forests for farms and changes in the climate are big reasons why species are being lost. Scientists worry that many species could disappear by the year 2050 if these problems continue.

Definitions

Biologists usually describe biodiversity as all the different genes, species, and ecosystems in a place. This helps us see the many kinds of life together. Biodiversity can mean the variety of species, the different ecosystems, or the many ways living things can look and act.

People sometimes use "biodiversity" instead of simpler words like "species diversity" or "species richness." But there isn’t just one way to define it. Different groups may describe it a little differently, but they all talk about the many forms of life on Earth.

Number of species

Main article: Global biodiversity

Scientists think there are about 8.7 million species that live on land and 2.2 million that live in the ocean. These numbers are guesses, especially for tiny organisms. Other guesses include:

• 220,000 vascular plants
• 0.7–1 million marine species
• 10–30 million insects
• 5–10 million bacteria
• 1.5-3 million fungi
• 1 million mites

We do not really know how many tiny organisms, like microbes, exist. But studies of ocean water have found many new genes, which might change how we think about what a species is.

Because many species are disappearing before we can study them, some may vanish without us even knowing they existed. Birds and mammals are the most studied animals, while fish and arthropods are studied less.

Current biodiversity loss

We have seen a big drop in the variety of life on Earth over the past century. Scientists think that up to 30% of all species might disappear by 2050. Many plants are also at risk, with about one in eight known species threatened.

The loss of different kinds of animals and plants is happening faster than ever before. Some studies show that by 2012, about 25% of all mammal species could be gone in just 20 years. This loss is caused mainly by human actions, like destroying places where animals and plants live.

Biodiversity helps keep our planet healthy, and losing it can make it harder for Earth to support all forms of life. Scientists warn that if we continue on this path, it could threaten our own future as well.

Distribution

Biodiversity is not spread evenly around the world. It changes a lot depending on where you are, like the temperature, rain, height above sea level, and the types of soil. The places where there is the most life are usually warm and rainy, especially near the equator. For example, rain forests such as Yasuní National Park in Ecuador have lots of different plants and animals.

Biodiversity is very important for our daily lives. It affects things like having clean water, choosing different foods, and finding materials for energy. Forests are especially important because they are home to most of the world’s land animals and plants. They help protect many species and also support people by providing resources and jobs through tourism. However, problems like pollution, using too many resources, and changes in climate can harm biodiversity around the world.

Latitudinal gradients

Main article: Latitudinal gradients in species diversity

Generally, there are more types of plants and animals near the equator than near the poles. This pattern is called the latitudinal gradient in species diversity. Scientists think this happens because it is warmer near the equator, which helps more species to live there.

Biodiversity Hotspots

A biodiversity hotspot is a place with many special plants and animals that are found only there, but which are also in danger because their homes are being destroyed. These hotspots are often forests, and many are located in warm areas near the equator. Countries like Brazil, Madagascar, India, and Colombia have many hotspots. For example, Colombia has more types of birds than all of Europe and North America combined. These special places need protection to save the unique life they support.

Evolution over geologic timeframes

Main article: Evolution

Biodiversity has grown over 3.5 billion years through evolution. Early life was simple, made up of tiny organisms like bacteria. Around 540 million years ago, many new kinds of animals appeared quickly in a time called the Cambrian explosion.

Even with these bursts of growth, there have been times when many species disappeared suddenly, called mass extinctions. One famous example is when the dinosaurs went extinct about 66 million years ago. Despite these losses, life kept growing and changing. Today, scientists think Earth may have up to one trillion species, but we’ve only found a tiny fraction of them. Most living things are found in tropical forests, and land usually has more species than the oceans.

Role and benefits of biodiversity

Ecosystem services

Further information: Ecosystem services and Ecological effects of biodiversity

Biodiversity helps provide important services for the environment. These services include giving us food, wood, and clean water, as well as helping control the climate and protect against pests and diseases.

There are three main types of these services:

1. Providing services like food, wood, and water.
2. Regulating services that help control the environment, such as managing the climate and stopping pests.
3. Cultural services that give us beauty, heritage, and places to enjoy the outdoors.

Experiments show that it is hard for humans to create ecosystems that work as well as natural ones. For example, machines cannot replace insects that pollinate plants, which is very important for growing food. The work of pollination alone is worth a lot of money each year.

Provisioning services

Having more kinds of plants can help us get more food and wood. Different types of plants can increase how much food we grow and how much wood we produce.

Regulating services

Biodiversity helps keep ecosystems strong and able to deal with changes. Different plants and animals can work together to help each other, which keeps the environment balanced. This can help protect against diseases and climate changes.

Agriculture

Main article: Agricultural biodiversity

Farming can include many different kinds of plants and animals. Some are planned, like the crops farmers grow, while others come naturally, like helpful insects that pollinate plants or pests that can cause problems.

Even though most of our food comes from just a few types of plants, many more species are used in different ways. Biodiversity gives us many options for food and other products, even though some species are disappearing.

Human health

Biodiversity is important for our health. It affects what we eat, helps prevent diseases, and provides materials for medicines. Many medicines come from plants, animals, and tiny organisms. Different kinds of ecosystems, like wetlands, also help protect communities from flooding and other natural events.

Business and industry

Further information: Economics of biodiversity

Biodiversity helps the economy by providing resources worth a lot of money each year. It supports businesses by keeping ecosystems healthy, which helps with things like clean water and stable climates.

Cultural and aesthetic value

Biodiversity also has value because it is beautiful and important to many cultures. It gives us places to learn, grow, and find meaning.

Measuring biodiversity

Most of the animals and plants we know about haven't been studied much. The majority of life on Earth is made up of tiny organisms that we can't always see. These tiny organisms are very diverse and can live in many different places. Scientists often focus on larger animals and plants, but there is much more variety in the tiny creatures we don't always notice. Some animals, like insects, are at risk of disappearing, which is a concern for scientists studying life on our planet.

Biodiversity changes (other than losses)

Natural seasonal variations

Biodiversity naturally changes with the seasons. In spring, many animals breed and plants grow, increasing diversity. In winter, some insects die and animals migrate, which can lower diversity temporarily.

Introduced and invasive species

Main articles: Introduced species and Invasive species

Barriers like rivers, seas, oceans, mountains, and deserts help create diversity by allowing species to evolve separately on each side. Sometimes, species cross these barriers and become invasive. These species can take over areas meant for native species.

Humans often move species from one place to another, either on purpose or by accident. This can lead to invasive species taking over new areas. While some studies suggest that diverse ecosystems can resist invasive species better, invasive species often reduce the variety of native species.

Hybridization and genetic pollution

Endemic species can be threatened when they mix with other species through uncontrolled hybridization. This mixing can weaken rare species by blending their genes with more common species, making it hard for the rare species to survive.

Conservation

Main article: Conservation biology

Conservation biology grew in the middle of the 1900s when scientists started studying and working on problems related to decreasing life on Earth.

The idea of conservation is to manage nature’s resources to keep different plants and animals, their homes, and how they change over time safe for both nature and people.

Conservation plans now focus on protecting all forms of life. These plans aim to include people, their communities, and nature at local, regional, and global levels. They find ways to help people live well while using nature wisely. In some places, zoos help protect animals by doing research and taking part in special breeding programs.

Protected areas

Further information: Protected areas

Protected areas, like forest reserves and special nature areas, help keep wild animals and plants safe. These areas are set up all around the world to protect nature. Some scientists suggest protecting 30% of Earth by 2030 and 50% by 2050 to help save many plants and animals. In 2022, almost 200 countries agreed to protect 30% of Earth by 2030. At that time, 17% of land and 10% of oceans were already protected.

Protected areas help nature and also support people, especially in local communities. There are over 238,000 protected areas covering about 15% of Earth’s land. These areas give many benefits, like clean water, medicines, and places for people to enjoy nature.

National parks and wildlife sanctuaries

Main articles: National park and Wildlife sanctuaries

A national park is a big natural area where governments or groups work to protect plants, animals, and natural processes. These parks also aim to teach people about nature and give chances for visitors to enjoy the outdoors. Wildlife sanctuaries are special places that help animals which cannot live on their own, or give animals a safe place to get healthier.

Both national parks and wildlife sanctuaries help keep biodiversity safe. They work to keep ecosystems healthy and teach the public about wildlife.

Forest protected areas

Forest protected areas are parts of forests set aside to keep them safe. About 18% of the world’s forests, more than 700 million hectares, are inside protected areas like national parks. Forests are home to many plants and animals, including some that live only in certain places.

In forest reserves, people living near forests may be allowed to do some activities, like hunting or grazing, which help them live. In Europe, about 24% of forest land is protected to help nature and the landscape.

Role of society

In 2019, a big report about nature and its resources was shared with leaders around the world. It said that nature is changing faster than ever before, and we need big changes to help protect it. This includes better farming, using fewer things, and working together to manage our water.

People can also help scientists learn more about nature by sharing what they see. Many people around the world help collect important information about plants and animals, which helps scientists understand how to protect nature better. Websites like iNaturalist and eBird make it easy for everyone to share their observations.

Legal status

Global agreements help protect plants, animals, and natural areas. These agreements ask countries to take care of their natural resources, share benefits fairly, and work together to protect the environment. In 2022, almost every country agreed to protect 30% of land and oceans by 2030, along with other goals to stop the loss of nature.

The European Union has its own plan to protect nature by 2030. This includes protecting parts of the sea and land, planting billions of trees, and reducing harmful chemicals used in farming. Many jobs and money in Europe depend on healthy nature.

History of the term

The idea of biodiversity started to grow in the early 1900s. In 1916, a scientist named J. Arthur Harris talked about "biological diversity" in a magazine called Scientific American. Later, in 1967, Raymond F. Dasmann used the term "biological diversity" in a book about protecting nature.

Over the years, more scientists began using the term. By 1980, Thomas Lovejoy helped make "biological diversity" popular in science. In 1986, the short word "biodiversity" was created. Since 1988, the United Nations has worked on agreements to protect biodiversity, with meetings happening all over the world. The most recent meeting was in Cali, Colombia, in 2024.