The Palaearctic ecozone is the world's largest. It covers northern Africa, Europe, the northern part of Arabia and all of Asia north of the Himalayas. Japan and Iceland are also part of this ecozone.
The largest of the ecozones the Paleartic is a predominately a temperate region encompasing Europe, Asia north of the Himalaya foothills, northern Africa, and the northern and central parts of the Arabian Peninsula. The ecozone is bounded by the tundra and the vast "boreal forest" known as the taiga in the north and deserts to the south. South of the taiga is a belt of Temperate broadleaf and mixed forests and Temperate coniferous forests. Although this European-Siberian region is characterized by shared plant and animal species it does share similarities with the the temperate and boreal regions of the Nearctic ecoregion of North America. Eurasia and North America were often connected by the Bering land bridge, and as a result have similar mammal and bird fauna, with many Eurasian species having moved into North America (including the Brown Bear, Red Deer, American Bison, and Reindeer), and fewer North American species having moved into Eurasia.
The lands bordering the Mediterranean Sea in southern Europe, north Africa, and western Asia are home to the Mediterranean basin ecoregions, which together constitute world's largest and most diverse mediterranean climate region of the world, with generally mild, rainy winters and hot, dry summers. The Mediterranean basin's mosaic of Mediterranean forests, woodlands, and shrub are home to 13,000 endemic species.
Broadleaf forests are the dominant habitat of the UK and most of temperate northern Europe. There's little left of Britain's ancient wildwood, but isolated pockets of oak, beech and mixed deciduous and evergreen woodlands are scattered across the continent, and dictate its biodiversity.
Coastal cliffs are the rocky land edges that face the sea. These are complex and diverse habitats that lie above the water line, where exposure to salty spray, wind, sun and rain all play their part, as does the type of rock.
The coniferous forests of temperate regions undergo warm summers and cool winters, unlike their tropical counterparts. The species aren't exclusively conifers, there are usually a few broadleaf varieties too.
Desert and dry scrubland describes any area that receives less than 250mm of rainfall a year. Not just the endless, baking sand dunes of popular conception, it includes arid areas in temperate regions.
Flooded grasslands are the half grassland, half wetland typified by the Florida Everglades, the marshes of Southern Iraq and the Pantanal of Brazil. They may be permanently or seasonally flooded, which has an obvious effect on what kinds of plant and animal species found here.
Mediterranean forest includes the fynbos of South Africa, the matorral of Chile and forests in parts of California. Hot, dry summers, contrast with much milder, wetter winters.
Mountain grasslands such as those in the Ethiopian highlands, on the Tibetan Plateau and up in the Andes, include the alpine tundra above the treeline as well as grasslands below it. These high altitude grasslands often exist as isolated 'islands' in a sea of another habitat type.
Polar regions, found at the planet's northern and southern extremes, are the icy wastes of the continental ice caps and the frozen pack ice of the ocean. The only 'plants' here are specialised forms of cold-loving algae that grow on the surface of snow.
Rainforests are the world's powerhouses, the most vital habitats on the planet. Characterised by high rainfall, they only cover 6% of the Earth across the tropical regions, but they contain more than half of its plant and animal species.
The taiga is the largest land habitat - a northern zone of coniferous forests, stretching right round the planet from western Alaska to eastern Siberia. In the winter the temperature can drop to as low as -50 degrees Celsius and the taiga is blanketed in snow.
Temperate grasslands include the prairies of North America, the steppes of Russia and the pampas of Argentina. Summers here are mild to hot and the winters can sometimes be very cold – for instance, blizzards can blanket the great plains of the United States.
Tundra is the cold, treeless region around the poles that has permafrost as one of its defining features. Even at the height of summer, the soil a few centimetres under the surface remains frozen.