Biomes of the World
Jan 11, 2016
Biomes of the World
Biomes• Definition: geographic region of Earth that is
inhabited by a community of distinct types of plant and associated animal species
• Biomes are primarily classified and defined by climate (average annual temperature and precipitation) and soil type
Characteristics of Biomes
Desert• Found on every continent except Europe (between 30°N & 30°S latitude)
Primary Regions
• Drastic day/night temperature shifts (50°F -130°F)
Climate & Soils
• Less than 10 inches of precipitation per year• Soils: are very thin and porous
Major Vegetation• Bushes, shrubs, cacti• Xerophytes – plants specifically designed for dry climates (spines, water storage structures, waxy covering)
Animals include: Rodents, lizards, reptiles, hawks, owls, and insects
Many animal species are nocturnal due to heat
Many animals estivate – hibernate due to heat
• Very low productivity
Environmental Concerns• Cover >1/3 of the Earth’s land surface and are expanding!
Desertification is the expansion of dry lands due to poor agricultural practices (e.g. overgrazing, degradation of soil fertility and structure), improper soil moisture management, salinization and erosion, forest removal, and climate change.
Grasslands
• Occur in inland prairies• Average temperature varies from freezing to 90’s
(wet cooler season followed by hot and dry season)• 10 to 60 inches of rainfall per year, seasonal drought
is common • During drought fires can be a problem (also can be
beneficial)---Why?• Soils rich and often deep
Grassland Climate & Soils
• Many animals are grazers: Bison, antelope, rodents, deer, kangaroos, giraffes, zebras, rhinos
Grassland Animals
• Some predatory animals: wolves, coyotes, hawks, golden eagle, lions, cheetahs, hyenas
Environmental Concerns : Grassland
• Much of the grasslands have been converted to croplands (farming)
• Overgrazing is common and may convert grasslands to desert like conditions.
US Grasslands• Bread Basket – middle of the United States• These grasslands have been converted to farmland
Savanna• Mixture of tree and grasslands found in Africa, South
America and Australia• Most are found in warmer dry tropics and subtropics; on
the sides of rainforests
Animals: Grazing and carnivorous animals: similar to the
grasslands.
• Rainfall: 20-50 inches; drought is common for about 4 months a year
• Fire can be a problem and beneficial – WHY?
• Soils are thin and porous
Environmental Concerns: Savanna• Animal Poaching• Overgrazing and land clearing for crops
Tropical Rainforest• Over 100 inches of rainfall per year (can reach nearly
200 inches)• Found near the equator
Climate & Soils: Tropical Rainforest
• Temperature is very stable year round: 80’s-90’s
(non-seasonal)• Soil is thin, acidic, nutrient-poor
Vegetation: Tropical RainforestVegetation grows in Four layers:
Tropical Rainforest Biodiversity
• Diverse plants, animals, insects, birds, reptiles, and primates
Tropical Rainforest: Environmental Concerns
• Estimated that half of all living species can be found here• Soils are thin, acidic and nutrient poor; clearing for
agriculture usually fails – WHY?• Erosion/Topsoil degradation• Habitat destruction• Global Warming
Deciduous Forest• The biome in which we live• Temperate climate: very seasonal (warm summers and freezing winters)• 30 – 80 inches of precipitation per year
Deciduous Forest: Vegetation
• Trees shed leaves annually• Typical trees: oak, maple, beech, birch, hickory, and some
coniferous trees (pines)• Soils are nutrient rich and can accommodate much growth
Deciduous Forest: Animals
• Animals are able to adapt to seasonal change (hibernate)
Deciduous Forest: Environmental Concerns
• Deforestation can lead to: soil erosion, flooding problems, habitat destruction
• Acid rain greatly affects growth• Urban Sprawl & Development
Coniferous Forest• Often called the Taiga• Found along a northern belt in which needle
trees/conifers dominate (pine, spruce)
• Trees are able to conserve water• 15-40 inches of precipitation per year
• Soils are acidic and nutrient poor (little undergrowth)
• Long cold winters and short summers
Coniferous Forest: Animals
• Moose, elk, deer, hares, wolves, coyotes
Coniferous Forest : Environmental Concerns• Pesticide sprays greatly affect food chains (eagles and birds
of prey)• Logging industry a big problem in clearing many forests
Temperate Rainforest• Mixture of deciduous and coniferous forest• Found in Northern areas between
coniferous and deciduous forests• Receive 80-100 inches of rainfall per year
Temperate Rainforest: AnimalsGrizzly bears, salmon, deer, moose, eagles
Temperate Rainforest: Plants
Mixture of Trees
Temperate Rainforest: Environmental Concerns
• Logging Industry a huge problem
Tundra• Northernmost land biome• Expands into the arctic/polar regions
Tundra: Climate & Soils
• Bitter cold temps: barely above freezing for only 8 weeks
• Characterized by Permafrost: Frozen ground which could be over 1,000 feet deep
• Less than 10 inches of precipitation per year• Very low productivity
Tundra: Major Vegetation
• Only about 8 weeks of plant growth where the top of the permafrost thaws
• During growth: grasses, lichens, dwarfed trees, shrubs
Tundra : Animals• caribou, hares, snowy owl, musk ox, lemmings,
ptarmigans
Tundra: Environmental Concerns
• Oil spills in Alaska and Russia have been problems• Oil exploration
Polar• Located in the Arctic and Antarctic regions, also Greenland
• Considered a “Desert” (coldest)• Extension of the tundra, but harsher• Slightly colder, less of a growth period (only at the
edges)
• Animals: Polar bears, seals, some bird species,
lemmings, walrus