Animals, plants, and all living things are adapted to life in their natural surroundings. These different environments are called habitats.
Every living species on Earth has its own favoured habitat, which it shares with others. These different species interact with their natural environment – be it cold or hot, wet or dry – to create a web of life called an ecosystem. Some ecosystems are very small, but others such as rainforests or deserts cover huge areas. These vast wild habitats are called biomes.
An ecosystem is constantly changing, as different types of living things move in and push out the species that lived there before – a process known as ecological succession. A bare patch of ground, for example, will be colonized by low – growing plants. Soon bigger plants take root, and then small bushes. Trees move in and grow tall to create a woodland. If the trees are then destroyed by a disaster, the series of changes, or succession, starts over again.
Different stages of a succession often occur near each other in the same habitat. Here, new plants are colonizing a forest clearing.
All animals, plants, fungi, and microbes depend on other forms of life for their survival. These communities of living things provide each other with shelter, food,plant nutrients, and even vital oxygen. All ecosystems are shaped by the climate, which influences the plants that grow. The cacti that grow in deserts, for example, are unlike the trees of a tropical rainforest, and they support different types of animals. The rock type is also important, because this affects the minerals in the soil, and in the water of streams,lakes, and other freshwater habitats. Mineral – rich water is very fertile, so it supports a lot of microscopic algae and water plants. These are eaten by small creatures that feed fish and other animals.
A pond is a miniature ecosystem. The plants in the water support the animals, and they, in turn,provide nutrients for the plants to grow.
Submerged plants release oxygen into the water. Other plants float on the surface or grow in the shallows.
Pond water is full of microscopic algae and tiny creatures, which are eaten by bigger animals such as fish.
Hunters like this Heron prey on fish and frogs. It may visit several ponds – no ecosystem is completely isolated.
The Everglades in southern Florida, USA, is the biggest freshwater habitat in the world.
Life on land
Different climates create different types of habitat for life on land. Warm, wet places grow lush forests, for example, while hot, dry regions develop deserts. These are just two of the world’s principal habitat divisions, or biomes. Each biome consists of many smaller habitats and, in many areas, human activities such as farming has completely changed their character.
Vast areas of Scandinavia, Russia, Alaska, and Canada are covered with coniferous forest – home to moose, beavers, and wolves.
High mountain ranges have arctic climates near the peaks, where few plants grow. Animals must cope in dangerous terrain.
These tropical grasslands with wet and dry seasons support huge herds of grazing animals and powerful predators.
The ice that forms on cold oceans is a refuge for animals that hunt in the water. The continental ice sheets are almost lifeless.
The evergreen forests that grow near the equator are the richest of all biomes, with a huge diversity of plant and animal life.
Some deserts are barren rock and sand, but many support a range of plants and animals adapted to survive the dry conditions.
These regions on the fringes of polar ice sheets thaw out in summer and attract animals such as reindeer and nesting birds.
Dry Scrub regions, such as around the Mediterranean, are home to a rich insect life and drought – resistant shrubs and plants.
The dry, grassy prairies with hot summers and cold winters, support grazing herds such as antelope and bison.
In cool, moist regions, many trees grow fast in summer but lost their leaves in winter. The wild life here changes with the seasons.
The largest biome of all is the ocean, covering almost three quarters of the planet’s surface. It includes a wide variety of marine habitats, ranging from tropical coral reefs to the polar seas and the dark ocean floor. Many animals and aquatic plants also live in freshwater habitats, such as rivers, lakes, marshes, and swamps.
The greatest threat to the world’s wildlife is the loss of their natural habitats. Most living things have evolved to live in a particular ecosystem, and they cannot survive if this is destroyed. Habitat loss is the main reason why many wild species are becoming rare.
Every day, a vast area of wild forest is felled for its timber, or to clear the land for agriculture.
Some facts :
- 1 single oak tree forms a habitat for an amazing variety of wildlife, with hundreds of animals living in its branches.
- All the habitats on earth are part of one huge global ecosystem that we call the biosphere.
- Some life forms live inside other living things – even your body is a habitat for microbes such as bacteria.
- 2 per cent of the original wild prairie in North America survives.The rest is now farmland.
Knowledge Encyclopedia, DK Publications.