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Major Biomes of the World
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Major Biomes The structure and distribution of terrestrial biomes are controlled by climate and disturbance Terrestrial biomes can be characterized by distribution, precipitation, temperature, plants, and animals Biome patterns can be modified by disturbance such as a storm, fire, or human activity Tropical forest Savanna Desert Chaparral 30ºN Tropic of Cancer Temperate grassland Equator Temperate broadleaf forest Tropic of Capricorn Northern coniferous forest 30ºS Tundra High mountains Polar ice
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Major Biomes Tropical Forest
In tropical rain forests, rainfall is relatively constant, and temperature is always warm Tropical forests are home to millions of animal species, including an estimated 5–30 million still undescribed species of insects, spiders, and other arthropods Tropical forests are being chopped down worldwide for timber mills and farmland A tropical rain forest in Borneo
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Major Biomes Desert Precipitation is low and highly variable, generally less than 30 cm per year; deserts may be hot or cold Desert plants are adapted for heat and desiccation tolerance, water storage, and reduced leaf surface area Common desert animals include many kinds of snakes and lizards, scorpions, ants, beetles, migratory and resident birds, and seed-eating rodents; many are nocturnal A lot of deserts are being artificially irrigated so people can live in them A desert in the southwestern United States
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Major Biomes Savanna Savanna precipitation and temperature are seasonal Grasses and shrubs make up most of the ground cover Common inhabitants include insects and mammals such as wildebeests, zebras, lions, and hyenas Areas closer to humans are becoming overrun with trees, areas further away are being slowly converted to deserts A savanna in Kenya
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Major Biomes Temperate Grassland
Temperate grasslands are found on many continents Winters are cold and dry, while summers are wet and hot The dominant plants, grasses and shrubs, are adapted to droughts and fire Native mammals include large grazers and small burrowers Humans are converting much to farmland or areas for housing Cheyenne National Grassland in No. Dakota
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Major Biomes Northern Coniferous Forest (Taiga)
The northern coniferous forest, or taiga, extends across northern North America and Eurasia and is the largest terrestrial biome on Earth Winters are cold and long while summers may be hot Animals include migratory and resident birds, and large mammals Plants are mainly evergreen trees such as pine Tiagas are facing enormous pressure from logging companies because of the large hardwood trees Rocky Mountain National Park in Colorado
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Major Biomes Temperate Deciduous Forest
Winters are cool, while summers are hot and humid; significant precipitation falls year round as rain and snow Mammals, birds, and insects make use of all vertical layers in the forest Major producers in biome include large trees that lose their leaves seasonally Much of this biome is being destroyed by people for either farmland or housing Great Smoky Mountains National Park in North Carolina
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Major Biomes Tundra Tundra covers expansive areas of the Arctic; alpine tundra exists on high mountaintops at all latitudes Winters are long and cold while summers are relatively cool; precipitation varies Vegetation is herbaceous (mosses, grasses, shrubs, dwarf shrubs and trees, and lichen) and supports birds, grazers, and their predators Tundras are slowly being overtaken with larger trees and shrubs because of the gradual warming of the climate of the world Denali National Park, Alaska, in autumn
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Major Biomes LAKES Eutrophic lakes are shallower and have increased nutrients Oligotrophic lakes are nutrient-poor and generally oxygen-rich The most pressing environmental issue surrounding lakes is how people are dumping wastes into them which kill all plant and animal life
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Major Biomes The organic and inorganic sediment at the bottom of all aquatic zones is called the benthic zone The communities of organisms in the benthic zone are collectively called the benthos Many aquatic biomes are stratified into zones or layers defined by light penetration, temperature, and depth Detritus, dead organic matter, falls from the productive surface water and is an important source of food for benthic organisms The upper photic zone has sufficient light for photosynthesis while the lower aphotic zone receives little light Intertidal zone Neritic zone Oceanic zone Littoral zone Limnetic zone Photic zone 200 m Continental shelf Pelagic zone Benthic zone Aphotic zone Photic zone Pelagic zone Benthic zone Aphotic zone 2,000–6,000 m Abyssal zone (a) Zonation in a lake (b) Marine zonation
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