Holarctic realm facts for kids

The Holarctic realm is a huge area on Earth. It covers most of the land in the Northern Hemisphere. Think of it as a giant neighborhood for plants and animals that live in similar cool or cold climates. This realm includes two main parts:

• The Nearctic region: This is most of North America.
• The Palearctic region: This covers North Africa and almost all of Eurasia.

These two regions share many types of plants and animals. This is because they have a similar history, especially from the Ice Ages.

What are the main types of places?

The Holarctic realm has many different kinds of environments, called ecosystems. The type of ecosystem depends on how far north it is and the local land features.

• Far North: Close to the Arctic Ocean, you'll find tundra. The ground here is frozen all year round, called permafrost. Only a few tough plants can grow in these cold, harsh conditions.
• South of the Tundra: A huge boreal forest stretches across North America and Eurasia. This forest is full of coniferous trees, like pines and spruces.
• Further South: The environments become more varied. Some areas are temperate grasslands, like prairies. Others are temperate forests with deciduous trees, which lose their leaves in winter.
• Southernmost Parts: Many parts of the Holarctic's southern areas are deserts. Here, plants and animals are specially adapted to dry conditions.

Animals living across the Holarctic

Many animal species live across large parts of the Holarctic realm, spanning different continents. Some well-known examples include the brown bear, grey wolf, red fox, wolverine, moose, caribou, golden eagle, and common raven.

• The brown bear (Ursus arctos) lives in mountains and open areas. They used to live in many more places. But human development has pushed them into wilderness areas.
• The grey wolf (Canis lupus) can live in many habitats, from tundra to desert. They once lived almost everywhere in the Holarctic. But human activities have removed them from many areas.
• The red fox (Vulpes vulpes) is a very adaptable hunter. It lives in more places than any other land carnivore. It can even live in areas with lots of human activity.
• The wolverine (Gulo gulo) is a large member of the weasel family. It mainly lives in the Arctic and boreal forests. You can find it in these areas across Eurasia and North America.
• The moose (Alces alces) is the biggest member of the deer family. It lives in most boreal forests in Eurasia and North America.
• The caribou or reindeer (Rangifer tarandus) lives in boreal forests and tundra in the northern Holarctic. In Eurasia, people have domesticated some reindeer.
• The golden eagle (Aquila chrysaetos) is a famous bird of prey in the Northern Hemisphere. It's the most widespread eagle species. Golden eagles are fast and strong. They use their sharp talons to catch prey like hares and marmots.
• The common raven (Corvus corax) is one of the largest and most widespread corvids (a family of birds). It lives in many habitats, especially northern wooded areas. Ravens can adapt well to places where humans live.

Some smaller creatures also have a wide Holarctic distribution:

• Leptothorax acervorum is a small red ant. It lives across Eurasia, from Spain to Siberia.
• Zygiella x-notata is a type of orb-weaving spider. It mostly lives in cities and towns in Europe and parts of North America.

How did the Holarctic realm form?

The similar environments in the northern Holarctic are due to their shared history. During the Pleistocene epoch, also known as the Ice Age, these areas had many periods of glaciation. Giant ice sheets grew and covered the land.

When the glaciers melted, plants and animals quickly spread into the new open areas. Different species moved at different speeds. For example, trees spread out from small safe areas called refugia. Insects were very mobile. They could move easily as the climate changed, keeping their habitats. Even plants, which seem to move slowly, colonized new lands quickly. Brown bears also moved fast after the glaciers retreated.

The last Ice Age ended about 10,000 years ago. This led to the way ecosystems are distributed today.

Another reason for the shared species is the Bering land bridge. This was a land connection between Asia and North America. It appeared when sea levels dropped because so much water was locked up in ice. This bridge allowed animals to move between the Palearctic and Nearctic regions. This is why these two regions share many species, especially large, cold-tolerant animals.

What are the threats to the Holarctic?

The Holarctic is a huge area, so it faces big environmental problems. The main threats are global warming and habitat fragmentation.

• Global Warming: This is a big worry, especially in the north. Animals and plants there are used to cold weather. Even a small warming can upset their balance. For example, milder winters mean more insects survive. This can lead to huge insect outbreaks. Spruce beetles have destroyed many spruce trees in Alaska because of warmer years. Warming temperatures also allow pest species to spread into new areas.

Melting permafrost is another problem. As the frozen ground melts, trees might die, and the land can change from forest to peatland. This melting also releases carbon (as carbon dioxide or methane) into the air. These are greenhouse gases, which can speed up climate change even more.

• Habitat Fragmentation: This means natural habitats are broken up into smaller pieces. This happens when land is used for farming or cities. When animal populations are cut off, their genetic diversity suffers. They become more likely to face sudden disasters or even extinction.

Many developed countries are in the Holarctic. Their temperate forests have been replaced by farms and cities. This makes it hard for animals, especially large ones, to move around. Large carnivores like brown bears and wolves need huge areas of undisturbed land to survive. Their survival is important for the whole ecosystem.

What is being done to protect the Holarctic?

People are working to protect the Holarctic realm and its amazing biodiversity.

• Fighting Global Warming: International agreements like the Kyoto Protocol aim to reduce greenhouse gas emissions. Many countries in the Holarctic are part of these efforts. The goal is to lessen the effects of climate change on the region and the world.

• Fighting Habitat Fragmentation: Efforts are being made to connect habitats. This includes creating reserves and safe routes for animals to cross roads. A big effort in North America is the Yellowstone to Yukon Conservation Initiative. This group works to create a connected network of protected areas in the Rocky Mountains. The goal is to link existing parks and wild areas with corridors. This helps wide-ranging animals like grizzly bears move freely. If these large species can survive, it helps many other species in their ecosystems too.

Images for kids

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  The Holarctic realm covers most of the Northern Hemisphere.

See also

In Spanish: Holártico para niños