What is a biome?

Tropical rainforest

• 23.5° north – 23.5° south of the equator.
• Hot and wet all year.
• Around 12 hours of sunshine all year round.
• Rich in plants and animals.
• Almost all plants are evergreen (they don’t drop their leaves in a particular season).
• Plants grow quickly and are adapted to take in maximum light.
• Dense vegetation provides food and habitats for many species of animals.
• Poor soils as nutrients are rapidly recycled as leaves decompose quickly, providing a constant supply of nutrients to the soil. 

Tropical grassland or savanna

• Within the tropics. Mainly between 5° and 15° north and south of the equator.
• Lots of sunshine throughout the year.
• Relatively low rainfall (800-900mm).
• Hot with a wet and dry season.
• Fires are common in the dry season.
• Temperatures are highest (around 35°C) just before the wet season and lowest (around 15°C) just after it. 
• Mainly grass, scrub, small plants and a few specially adapted trees e.g. acacia. These plants are adapted to recover quickly after a fire. 
• Many species of insects.
• Large mammals such as lions, elephants, giraffes and zebras.
• Thin, nutrient-rich soil formed as the grass dies back or burns during the dry season.
• Nutrients are washed out (leached) during the wet season.

Desert

• 15-30° north and south of the equator.
• Located in a belt of high pressure (sinking air) and low rainfall.
• Low rainfall (less than 250 mm per year).
• It might only rain once every two or three years.
• Very hot and dry.
• High range in temperatures between very cold night temperatures (0°C) and hot daytime temperatures (e.g. 45°C)
• Hot deserts get more daylight during the summer than in the winter.
• There is little cloud cover because they get lots of sunshine hours during the day.
• Plant growth is sparse due to limited rainfall.
• Vegetation includes cacti and thornbushes.
• Many plants have a short life cycle and appear only when it rains.
• Limited plants.
• Relatively few animals species, those that do exist have adapted to the harsh climate including scorpions, lizards, snakes and insects.
• Sparse vegetation means there is little leaf litter and high temperatures mean it is slow to decompose, leading to soils being thin and nutrient-poor.

Mediterranean

• 30-40° north and south of the equator.
• West coasts.
• Hot, dry summers and warm, wet winters.
• Mainly scrub vegetation – plants adapted to summer drought.

Mixed and Deciduous forest / Temperate forests 

• 40-60° north and south of the equator.
• High rainfall and mild temperatures in the mid-latitudes.
• Four distinct seasons.
• Warm summers and cool winters.
• Rain throughout the year, up to 1500 mm per year. 
• Days are shorter in winter and longer in summer.
• Hours of sunshine vary throughout the year.
• Fewer plant species than tropical rainforests.
• Rich deciduous woodlands.
• Forests are made up of broad-leaved trees that drop their leaves in autumn e.g. oak, shrubs and undergrowth.
• Mild climate and range of plants provide food and habitats for mammals such as foxes, squirrels and mice, birds and insects.
• Plants lose their leaves in autumn, and leaf litter decomposes quickly, so soils are nutrient-rich and relatively thick.

Temperate grassland

• 40-60° north and south of the equator (higher altitude and latitudes than tropical grasslands).
• 250-500mm of rainfall each year, mainly in late spring, early summer.
• Hot summers (up to 40°C) and very cold winters (down to -40°).
• Light varies throughout the year.
• Quite low rainfall.
• Mainly grassland vegetation.
• Rainfall is too low to support large plants, so there are few trees.
• Home to fewer species of animals than tropical grasslands.
• Mammals include bison and wild horses and rodents such as mole rats.
• Decomposition happens quickly in summer due to high temperatures. So soils are relatively thick and nutrient-rich.

Coniferous forest (Taiga) / Boreal Forest

• High latitudes, 60° north of the equator and on mountains.
• Long, cold winters (-20°C)
• Short, mild summer (-10°C)
• Limited precipitation (less than 500mm per year). Most of this falls as snow. 
• Lots of daylight during the summer months, little or none during the winter.
• Clear skies so plenty of sunshine during daylight hours.
• Most trees are evergreen, so they can grow whenever there is enough sunlight.
• Coniferous trees such as pine and fir are common, as are low-growing lichen and mosses. 
• Relatively few animals species because of the lack of food available.
• Animals include black bears, wolves and elk.
• Needles decompose slowly due to cold temperatures, so soils are thin, nutrient-poor and acidic.
• The soil is frozen for most of the year due to cold temperatures.

Tundra

• Far north, above 60°N in Northern Europe, Alaska and Russia. 
• Below freezing for most of the year.
• Summer 5-10°C, winter -30°C.
• Low precipitation – less than 250mm per year, most of which falls as snow.
• Near-continuous sunlight during the summer, and little or no sunlight during the winter.
• There is more cloud cover in the summer.
• Few trees due to lack of light in the winter. Vegetation includes mosses, grasses and low shrubs.
• Relatively few species of animals. Examples include Arctic hares, Arctic foxes and birds.
• Some animals migrate south during the winter.
• Sparse vegetation produces little leaf litter and organic matter decomposes slowly due to the cold temperatures.
• Soil is thin and nutrient-poor.
• Below the soil surface, there is a layer of permanently frozen land (permafrost). 
• Light snow.

Montane

• Very cold.
• Thin soils.
• Limited vegetation.

Polar

• Very cold all year round.
• A permanent or semi-permanent layer of ice.
• Mainly found in the Arctic and Antarctic.