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drjoe.biology.ecu.edu/ ch07/biome.jpg TERRESTRIAL BIOMES CAUSES OF BIOMES DESERT PRECIPITATION TEMPERATURE AND PRECIPITATION GRASSLAND TEMPERATE DECIDUOUS FOREST RAINFOREST TEMPERATURE TUNDRA TAIGA www.field-trips.org • Temperate deciduous forests contain dense stands of trees and have very cold winters and hot summers. The trees lose leaves and go dormant in winter. • This biome includes a large variety of plants and animals. • Humans have logged many of these forests around the world. Fig. 50.25f Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings TEMPORATE DECIDUOUS FOREST • North America • Rainfall mean 30-50 inches, falls throughout the year www.field-trips.org • Temperate forests grow throughout midlatitude regions with sufficient moisture to support growth of large, broad-leafed deciduous trees. Occur in Eastern U.S., Middle Europe and E. Asia. Temperatures range from very cold in winter to very hot in summers, with a 5 to 6 month growing season. Precipitation is fairly high and evenly distributed throughout the year. Soil is rich in nutrients • Several layers of vegetation including herbs, shrubs and one or two strata of trees (species composition varies widely) are present. • Variety and abundance of food and habitat supports a rich diversity of animal life. • Dominant plants—broad leaf trees • • Animal Adjustments—adapted structurally, functionally, and behaviorally to live or under trees. • Claws or sucking discs for climbing • Parachutes and bushy tails of squirrels • Hearing and voice well developed. TUNDRA • Tundra is at the northern-most limits of plant growth and at high altitudes and plant forms are limited to low, shrubby or matlike vegetation. • There are two types of tundra: •Location • Alpine- Tree line to perpetual snowline • Arctic- North of coniferous forest •Arctic Tundra • Precipitation—10 inches or less per year • Temperature - 30 to +50 degrees F • Frost anytime in North, 60 day frost free in South •Arctic tundra encircles the North Pole and is very cold with little light for long periods. •· Brief warm summers are marked by nearly 24 hours of daylight. •· Some areas are characterized by permafrost (permanently frozen ground), which contributes to the absence of taller plant forms. •· Soil is continuously saturated, further restricting plant forms. •· Dwarf perennial shrubs, sedges, grasses, mosses and lichens are common. • Most are perennials – too short growing season to produce seeds • Vegetative reproduction important • Tundra contains low growing plants. – The climate is windy and cold which causes a short growing season. – A layer of permafrost is found below 1 meter and does not thaw, which prevents root growth; not many animals live in tundra biomes. – There are two types, arctic, which is found in areas of Alaska and the Arctic circle, and alpine, which is found on very high mountaintops. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig. 50.25h Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Permafrost- ground frozen 1 foot down all year Soil wet and soggy in summer Uplifting – thawing Lakes frozen 9 months – oxygen disappears Photoperiod – no light in winter 24 hour light in summer www.cotf.edu/.../modules/msese/ earthsysflr/ www.saskschools.ca/~gregory/ arctic/animals www.saskschools.ca/~gregory/ arctic/animals www.nationalgeographic.com www.saskschools.ca/~gregory/ arctic/animals www.saskschools.ca/~gregory/ arctic/animals • Many animals are migratory and exhibit adaptations to the cold. Large animals are herbivores like musk oxen and caribou. Smaller animals are lemmings, arctic fox and snow owl. • Alpine Tundra • Alpine tundra occurs at high elevations in all latitudes • —mountain peak are islands to some organisms • Lacks permafrost – normal photoperiod • Soil thin and unstable • Great daily temperature flux (58 degree difference between night and day) • North slopes colder than South, some frost free period people.clemson.edu/.../habitats/ tundra1/tundra1 www.unc.edu/depts/geog/lcsal/ Images/gnp_drawing.gif www.rmnp.com/Flowers www.explore-rocky.com / • Precipitation and humidity high • Rapid streams, strong winds, high light intensity • Low barometric pressure, low oxygen concentration • Vegetation—sedges, rushes, lichens, mosses, shrubs, grasses, flowering herbs • --small stunted, adapted to resist desiccation, and abrasion from wind, snow, sand •Alpine Tundra Desert •Desert is characterized by low precipitation (< 30 cm/year)[ 10” ], not by temperature: both cold and hot deserts exist. • Deserts have low rainfall, and are generally hot. • Vegetation is usually sparse, and includes cacti and succulents. • Many animals are nocturnal, so they can avoid the heat. Fig. 50.25c Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings www.desertusa.com • The cycles of growth and reproduction are keyed to rainfall. • Scattered scrubs, cacti and succulents common. Many bloom abundantly after a rainfall. • Reptiles and seed eaters such as ants, birds and rodents are common • Many live in burrows, are nocturnal or have other adaptations for conserving water. GRASSLAND BIOME •The veldts of S. Africa, the pusta of Hungary, the pampas of Uruguay and Argentina, the steppes of Russia and the plain and prairies of the U.S. are examples. • Occasional fires and drought prevent encroachment of trees upon the grassland · Large grazing mammals and large carnivores are common. • Temperate grasslands exhibit seasonal drought, occasional fires, and are usually used for grazing and agriculture. Fig. 50.25e Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings mbgnet.mobot.org/sets/grasslnd www.uwsp.edu/geo/faculty/ritter/geog • Covers 42% of Earth’s land area • Precipitation = 10-40 inches/year • North American location = Adjacent to deciduous forest, taiga, and desert • Big daily temperature fluctuation • High evaporation rate and periodic droughts • Little snow but blizzards are common • Fires and grazing important for maintaining grasses • East- Tall-grass prairie / 25-30 inches per year: – Tall bluegrass, Switch grass, Indian grass, Corn • Middle- Mid-grass prairie /15-25” per year: – Little bluestem, Western wheatgrass, June grass, Wheat • West- Short-grass prairie 10-15” per year: • Buffalo grass, Blue grama grass Savanna • Savanna is grassland with scattered individual trees. • Covers areas of central S. America, central and S. Africa and parts of Australia. • Generally 3 distinct seasons: cool and dry, hot and dry, warm and wet, in that order. • Frequent fires inhibit invasion by trees to maintain the grasses (wind pollinated) and forbs (often insect pollinated). • Large herbivores (zebras, giraffes) and burrowing animals are commonly most active in the rainy season and many are nocturnal. • Savannas are grasslands with scattered trees, that show distinct seasons, particularly wet and dry. – They have many types of plants and animals. – Fire is an important abiotic factor. Fig. 50.25b Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings www.geog.ouc.bc.ca/ Tropical Forest • Tropical forest is found near the equator • where temperature varies little from approximately 25C • and the length of daylight varies from 12 hours by less than one hour. • Tropical forests are close to the equator, receive high amounts of rainfall (although this can vary from region to region), and contain a great variety of plants and animals. • The vegetation is layered, with the canopy being one of the top layers. Fig. 50.25a Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings • Rainfall is variable. Amount determines vegetation species in an area. Harbors more plants and animal species than any other community. Competition for light is strong selective force in plant communities. Soils poor due to rapid nutrient recycling. Animals are typically tree-dwellers. • Destruction of tropical rain forests, occurring rapidly due to human intervention, may cause large-scale changes in world climate as well as destruction of many species. •More than 90” of precipitation each year •Coniferous trees •Redwoods •Northern ½ of western coast of North America • Coniferous forests are the largest terrestrial biome on earth. – They exhibit long cold winters and short wet summers. – Conifers inhabiting them are adapted for the climate. – Conifer forests are home to various animals, some of which hibernate. Fig. 50.25g Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Located just below tree-line on Mountains Pine, Spruce, Fir, Hemlock