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