11. Vegetation zones

Vegetation zones form biomes

The vegetation zones of planet Earth loosely follow the borders of the planet's geographic zones and climatic regions. The main factors that influence the vegetation of a region are its temperature, precipitation and soil type. Precipitation or rainfall is influenced by the winds, mountain ranges and ocean currents that affect the region's climate.

The map below displays some of planet Earth's most significant vegetation zones. Human activity has an influence on vegetation, as forests and natural habitats are cut down to make way for land for habitation or agricultural use. As a result, a map of the planet's vegetation zones display the kinds of vegetation that would exist in a given region if it was free of human interference.

The vegetation zones of planet Earth form large egosystems known as biomes. Biomes are characterized by a dominant vegetation type. For example, the savanna biome is characterized by large areas of grassland, but it also contains river, forest and rock ecosystems. As a result, the savanna biomes of Africa are home not only to grassland-dwelling mammals such as elephants and antilopes, but also to river-dwelling hippopotamuses.

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The formation of biomes is explained by the variation in precipitation and soil type.

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The most significant vegetation zones of planet Earth.​

11.1 Rainforest

Tropical rainforests can be found in areas near the equator in South America, Africa and Southeast Asia. These tropical rainforests experience an endless summer. The monthly average temperature varies only a little throughout the year, remaining mostly between 25–27 degrees Celsius. 

Areas near the equator receive a lot of solar radiation. Tropical rainforest depend on this solar radiation, as it guarantees warm temperatures throughout the year. As the name of the vegetation zone suggests, tropical rainforests also experience a large amount of rainfall throughout the year.

The vegetation of a tropical rainforest rises in thick layers. The trees often grow tens of meters tall as they compete for sunlight. The plant life of the tropical rainforests is extraordinarily diverse. Over 50 percent of the world's known species of flora and fauna live in the tropical rainforests.

New, previously unknown species of organisms are found every year in tropical rainforests. Likewise, species that were unknown to science also become extinct every year. 


Rainforests are characterized by a rich variety of flora and fauna, as well as high amounts of rainfall. The picture shows a gorilla in an African rainforest.
 
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11.2 Savanna

Savannas are found both in Africa and South America. However, the South American savannas lack the magnificient mammal species you know from nature documentaries. These species are only found in the African savannas. 

Savannas are found in the tropical zone. They have formed in regions that experience both a rainy season and a dry season. 

The vegetation of the savanna consists of grasses, shrubs and trees. The long dry season is difficult for the flora of the savanna. During this time, the grass dries out and the trees and shrubs drop their foliage. The landscape becomes brown.

Finally, as the dry season gives way to the rainy season, large thunderstorms bring large amounts of rainfall to the savanna. During the rainy season, the landscape becomes green once again.


​ ​Savanna.

11.3 Desert

The best-known desert on Earth is probably the Sahara desert in North Africa. Deserts are found in many different continents, and they cover almost 20 percent of the planet's land surface area. 

Deserts receive only a little rainfall, but they are not completely waterless. Water can be found in deserts in the form of oases, which have formed as a result of underground water concentrations.

Desert plants have developed different strategies for conserving and storing water. For example, species of cacti store water by using their stems, leaves and roots. It is also possible for plants to slow down the evaporation of water, for example with hairy stems that gather moisture. 

The living conditions of the desert are also difficult for animals. The most common desert-dwelling animals are reptiles and rodents. As the days are extremely hot, many desert animals only become active during the night. During sand storms, the animals take shelter in caves and holes in the ground.

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11.4 Mediterranean vegetation or chapparal

As its name suggests, Mediterranean vegetation is mostly found in Mediterranean Europe. Similar vegetation is also found in some parts of the Americas, such as California and Chile, where the vegetation type is called chaparral.

In many areas, especially in Europe, the original Mediterranean vegetation has vanished as the result of human habitation and agriculture.

The vegetation zone is characterized by a long and hot summer that is balanced out by a short, temperate winter.

The plants of the Mediterranean vegetation zone have adapted to these climatic conditions with small, wax-covered leaves. These kinds of leaves prevent water from evaporating during the hot summer. Dry areas are dominated by shrubs, whereas regions that receive more rainfall are characterized by forests.


A typical Mediterranean landscape. The long, thin cypresses are characteristic to Mediterranean vegetation.​

11.5 Broadleaf forest

Broadleaf forests were previously common in Europe. Nowadays, only a small fraction of them remains. Broadleaf forests have been cut down by humans, because their nutrient-rich soil and climatic conditions are favorable for agriculture.

The broadleaf forests are very suitable for agriculture, because they receive the perfect amount of rainfall and solar radiation for crop growth. Many countries with productive agricultural sectors, such as France and Germany, are found in the broadleaf forest zone.

As their name suggests, broadleaf forests are characterized by the presence of broadleaf trees, such as oak, maple and beech.

Broadleaf forests are full of animal life: they are home to squirrels, hedgehogs, mice, boars and deer. Many frog and reptile species also thrive in broadleaf forests.


A broadleaf forest. The rich foliage of broadleaf trees prevents sunlight from reaching the ground level, which is why the undergrowth of the forest is sparse.

11.6 Northern coniferous forest

The zone of Northern coniferous forests circles the planet's northern hemisphere, covering most of Russia, Northern Europe, and North America. Approximately 15 percent of the planet's land surface area is covered by coniferous forest. Northern coniferous forest is also known as boreal forest or taiga.

The plants of the coniferous zone – coniferous trees, mosses, lichens, blueberries and lingonberries – form large populations in the forests of the northern hemisphere. They have adapted to cold and dark winters.

Spruce and pine are the two most common tree species of boreal forests, creating large lumber and paper industries in many countries of the coniferous forest zone.

Northern coniferous forests receive large amounts of rainfall. However, as the temperatures remain quite low throughout the year, only a relatively small fraction of this water evaporates.


A pine forest during the spring. Coniferous trees begin photosynthesis directly after the temperature rises above zero degrees Celsius.​

11.7 Tundra

The vegetation of the northern frigid zone must endure harsh climatic conditions. Only a few plant species are up to the task. In the northern frigid zone, the vegetation consists of low shrubs, grasses, mosses and lichens.

Tundras are almost completely free of trees. Tundra is found in the northernmost areas of Europe, such as Iceland, Norway and Russia.

During the summer, large insect populations lure migrating birds to tundra regions. Other animals of the tundra include small mammals, such as voles, as well as larger mammals, such as polar bears. 


The tundra is a barren environment.​

11.8 Temperate grassland

The soil type of temperate grasslands or steppes is rich in nutrients. Despite this, no trees grow in these areas. This is the case because there is not enough rainfall or moisture to maintain tree growth. 

The vegation of the temperate grassland consists of various kinds of different grasses and bulbous plants. These plants thrive in the dry conditions of the steppes.

Small rodents are the most common animals of the temperate grasslands. The large grasslands of North America, the prairies, are also home to larger mammals such as buffaloes.

11.9 Mountain vegetation

The mountain ranges of planet Earth are characterized by a special type of vegetation. When ascending a mountain, the air gradually becomes colder the higher one climbs. This results in a large amount of variation in mountain flora at different elevations.

In the temperate zone, the vegetation of mountain ranges consists of broadleaf and coniferous forests. Conifers such as spruce and pine thrive at higher elevations than broadleaf trees.

The term mountain vegetation refers to the scarce vegetation type found at high elevations. This kind of vegetation, which is similar to that found in northern tundras, is found in tall mountain ranges such as the American Cordillera and the Alps of Central Europe. 

In mountainous regions, the temperature variation between day and night is often drastic. The afternoons can be hot, whereas the nights can receive sub-zero temperatures. Different species of low shrubs and grasses have adapted to these conditions. 

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Summary

  • The vegetation type of a region is determined by the region's temperature, precipitation and soil type.
  • The vegetation zones of planet Earth include rainforest, savanna, desert, Mediterranean vegetation (chaparral), broadleaf forest, northern coniferous forest, tundra, temperate grassland (steppe) and mountain vegetation.