Terrestrial Biomes

 Terrestrial Biomes

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Biomes are defined by characteristic temperatures and amounts of precipitation. The tropical rainforest is the most diverse of these biomes, found in equatorial regions with stable temperature and sunlight profiles, and high rainfall supporting rapid plant growth. The forest is characterized by vertical layering of vegetation, providing diverse habitats for the variety of plants, animals, and other organisms within the biome. The loss of leaves from taller trees during the dry season allows the growth of thick ground-level brush, which is absent in tropical rainforests. Extensive tropical dry forests occur in Africa, India, southern Mexico, and South America.

Terrestrial biomes refer to major ecological regions on land characterized by distinctive vegetation and animal communities. Aquatic biomes include both ocean and freshwater biomes, while terrestrial biomes are based on land.

Eight major terrestrial biomes

There are eight major terrestrial biomes: tropical rainforests, savannas, subtropical deserts, chaparral, temperate grasslands, temperate forests, boreal forests, and Arctic tundra.

Tropical rainforests

• Equatorial regions.
• The most diverse terrestrial biome.  
• "evergreen," with year-round plant growth.
• Stable temperature and sunlight profiles, with average temperatures ranging from 20°C to 34°C (68°F to 93°F). 
• High net primary productivity because the annual temperatures and precipitation values support rapid plant growth. 
• High rainfall quickly leaches nutrients from the soils of these forests, which are typically low in nutrients.
• Characterized by vertical layering of vegetation and the formation of distinct habitats for animals within each layer. 

Tropical dry forests

• Characterized by a dry season of varying lengths and are found in Africa (including Madagascar), India, southern Mexico, and South America.
• During the dry season, taller trees lose their leaves, opening up the canopy and allowing sunlight to reach the forest floor, allows for the growth of thick ground-level brush.

Savannas

• Grasslands with scattered trees found in Africa, South America, and northern Australia
• Temperatures averaging from 24°C –29°C (75°F –84°F)
• Annual rainfall of 51–127 cm (20–50 in)
• Extensive dry season and consequent fires
• Dominated by grasses and forbs
• Relatively few trees due to fire disturbance
• Plants have well-developed root systems that allow them to re-sprout after a fire.

Subtropical Deserts

• Exist between 15° and 30° north and south latitude and are centered on the Tropic of Cancer and the Tropic of Capricorn
• Very dry with evaporation typically exceeding precipitation
• Daytime soil surface temperatures above 60°C (140°F) and nighttime temperatures approaching 0°C (32°F)
• Low annual precipitation of fewer than 30 cm (12 in) with little monthly variation and lack of predictability in rainfall
• Low species diversity due to low and unpredictable precipitation
• Desert species exhibit adaptations to conserve water
• Most animal has adapted to a nocturnal life
• North American deserts, Sahara Desert, Namib Desert in southwestern Africa

Cold Deserts

• Deserts that experience freezing temperatures during the winter and any precipitation is in the form of snowfall
• Gobi Desert in northern China, southern Mongolia, Taklimakan Desert in western China, Turkestan Desert, Great Basin Desert of the United States.

Chaparral

• Also called scrub forest found in California, along the Mediterranean Sea, and along the southern coast of Australia
• Annual rainfall ranging from 65 cm to 75 cm (25.6–29.5 in)
• Summers are very dry with many plants dormant during this season
• Dominated by shrubs and adapted to periodic fires
• Some plants produce seeds that germinate only after a hot fire
• Ashes left behind after a fire are rich in nutrients like nitrogen that fertilize the soil and promote plant regrowth
• Fires are a natural part of the maintenance of this biome and frequently threaten human habitation.

Temperate Grasslands

• Central North America, known as prairies, and in Eurasia, known as steppes
• Pronounced annual fluctuations in temperature with hot summers and cold winters
• Dense vegetation and fertile soils due to the subsurface of the soil being packed with roots and rhizomes