Ecosystems Continued
Biomes
The Earth is made up of a number of habitats or biomes. These are large-scale
communities of plants and animals that exist together in harmony (equilibrium)
with the environment. While scientists disagree on the number of biomes there
are in the world, some of the main ones are described below:
Deserts
Deserts include the world’s driest lands and may be hot like the Sahara or icy
cold like Antarctica. All deserts have one feature in common: an annual
rainfall of less than 400mm.
Thar desert, India
Almost one eighth of Earth’s surface is dry desert and these may have
temperatures in excess of 40ºC during the day and yet at night, the temperature
can fall to 4ºC. This is because other biomes are insulated by their humidity
(water vapour in the air). Biomes like temperate forests may have in the region
of 80% humidity during the day and this water absorbs and reflects sunlight and
the energy it brings. At night the water acts like a blanket, trapping heat
inside the forest. Since deserts usually have only between 10 – 20% humidity to
trap and have few trees or vegetation to trap heat, they cool down quickly when
the sun sets and heat up quickly after the sun rises.
World’s largest Deserts
| Desert |
Location |
Area in km sq |
| Antarctica
|
Antarctica |
14,245,000 |
| Sahara |
North Africa |
9,065,000 |
| Gobi |
Mongolia - China
|
1,295,000 |
| Kalahari
|
Southern Africa |
582,000 |
| Great Victoria |
Australia |
358,000 |
| Great Sandy |
Australia |
358,000 |
Temperate Deciduous Forests
Temperate forests have four seasons, spring, summer, autumn and winter and grow
where rainfall, temperature and hours of sunlight change a lot through the
year. Animals and plants living within this biome have special adaptations to
cope with these yearly changes (while trees shed their leaves in winter, the
animals might keep active, migrate or hibernate).
Deciduous forest, Slovenia
Forests are considered the richest of all the biomes as they are home to at
least 50% of the world’s species. They produce nearly half the world’s total
organic matter and contain about half its total carbon store. Forests prevent
soil from being washed away by rain. They also act as Earth’s lungs by
producing oxygen from carbon dioxide, restoring oxygen levels in the
atmosphere.
Grasslands
Grasslands are big open spaces and seem like an endless ocean of grass.
Grasslands receive between 250 and 800mm per year. If they received more rain,
the grasslands would become forest and if they received less, the grasslands
would become desert. The plants are adapted to survive poor-quality soil,
frequent droughts, and fires. Grasslands include dry grasslands, scrublands,
and shrublands.
Steppe of western Kazakhstan
Grasslands
| Type |
Principal Locations |
| Temperate
|
Australia, China, Russia, North America |
|
Tropical
|
Sub-Saharan Africa, Mexico, Brazil |
Before it was reduced by the spread of ranching and crop farming, grassland
covered as much as two-fifths of Earth’s land surface. Temperate grasslands in
Europe are called steppe while in Africa the tropical grassland is known as
savanna.
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