Terrestrial biomes

The areas around the equator are hotter because the sunlight is less spread across a given area.

A terrestrial biome is determined by its temperature and level of rainfall.

The 10 major biomes:

Tropical rainforest:

Location: Equatorial regions

Physical environment: Rainfall exceeds 230cm/year, no dry season ,hot (25-29˚C) all year round, soils often shallow & nutrient-poor
Dominant plants: phanerophytes: trees, lianas, epiphytes

Animals: Diverse range of insects, amphibians, reptiles and mammals.

Rainforest levels:

Forest floor: Low light levels mean few ground flora so large animals are present.

Understorey: Plants: Shade-adapted shrubs & herbs, small trees, woody vines, and also seedlings of canopy trees. Animals: Insects, reptiles, birds, small mammals.

Canopy: Absorbs 95% of sunlight, dominated by evergreen trees, which house epiphytes and animals such as monkeys, birds and sloths.

Emergents: Trees that grow beyond the canopy and are more exposed to wind, home to species such as large flying foxes. 

Tropical deciduous forests:

Location: Equatorial regions with monsoon rainfall.

Physical environment: Rainfall 130-280 cm/year, hot (25-39˚C) all year round, has a 2-3 month dry season

Plants: Dominated by deciduous phanerophytes, understorey shows strong growth after leaf-fall, dense closed ‘tropical jungle’.

Animals: Diverse: large mammals well-represented

Temperate rainforest: 

Location: Coastal regions in higher latitudes

Physical environment: Rainfall exceeding 200 cm/year, condensation of water from coastal fog augments normal rainfall, rarely below freezing, rarely over 27 ˚C, slow decay – thick leaf litter

Plants: Coniferous or broadleaf phanerophytes; epiphytes, Understorey: ferns & mosses

Animals: UK forests have high animal diversity.

Taiga: (temperate coniferous  forest)

Location: Vast tracts of N. America and Russia

Physical environment: Precipitation 30-100 cm/year – mostly snow

Very cold, often below freezing for long periods

Soils are poor – needles decay slowly and build up, acidifying the soil

Plants: Coniferous phanerophytes: spruces, firs and pines dominate. Low tree species diversity. Trees are conical to reduce bough breakage from snow.

Understorey: sparse because of year-round canopy

Animals: Too cold for amphibians & reptiles, insects seasonal, Bears, lynx, moose, squirrels, elk

Temperate deciduous forest: 

Location: Eastern US, Northern Europe, eastern Asia, Southern South America, New Zealand, Australia

Physical environment: Rainfall 75-200 cm/year, temperatures do drop below freezing, but not usually below -12 ˚C, four seasons, soils are rich due to annual leaf-fall & are easily converted to agriculture

Plants: Dominated by deciduous broadleaf phanerophytes, much less diverse than tropical rainforest – 3-4 tree species per square km e.g., leaves are shed in Autumn, herbaceous plants get growth in before the canopy regrows in Spring

Animals: Adapted to a highly seasonal climate, many hibernate, birds may migrate, insects may enter diapause. 

 Non forest biomes:

Tropical grasslands (Savana):

Location:5-20 degrees from the equator

Physical environment: Low and highly seasonal rainfall, extensive dry season, temperatures of 24-29 C, frequent fires, soils are often poor due to rainfall leaching nutrients, overgrazing leads to desertification.

Plants: Dominated by hemicryptophytes, with scattered trees and shrubs some of which are adapted to fire either with easy recovery from fire or germination is triggered by fires. 

Animals: Diverse mainly consisting of migratory species, herbivores are grazer and predators include large cats such as lions..

Temperate grasslands:

Physical environment: Low annual rainfall 25-100 cm/year.

Wide range of temperatures from -10 C in the winter to >30 C in summer.

Soils have 12 times as much hummus as forest soils. Rainfall is affected by which side of a mountain range it's on, which affects levels of diversity.

Plants: Dominated by hemicryptophytes

Animals: Burrowers and grazers.

Hot desserts: 

Location: 30 degrees latitude.

Physical environment: Less than 30cm/year, evaporation is greater than precipitation, high salinity, extreme temperature differences between day and night.

Plants: Therophytes or xerophytes, cacti evolved barrel shaped bodies while agaves and crassula evolved tough skin.

Animals: Live on annual seeds, includes ants, birds and rodents.

Cold desserts: 

Location: Polar regions and continental interiors.

Physical environment: Less than 25 cm/year of precipitation (often in snow form), Freezing temperatures.

Tundras: 

Location: North of boreal forests, vast areas of Russia and Canada.

Physical environment: 25 cm/year of precipitation, growing seasons have long days but only have 50-60 of them, water is stored in the soil as permafrost (which stores CO2 and Methane).

Plants: No trees, small low lying lichen and plants.

Animals: Migratory birds, mammals include grazers and predators.

Bonus biome: Mountains

Location: Along continental convergent boundaries.

Physical environment: Changes with altitude, will border different biomes so animals and vegetation will vary from place to place. Biodiversity will decrease the higher the altitude.