The Major Biomes

1 The Major BiomesThis map shows the locations of the world's Major land Biomes . Other parts of Earth's surface are clas-sified as mountains or ice caps. Each biome has a characteristic climate and community of organisms. Ecologists recognize at least ten different Biomes . The world s Major land Biomes include tropicalrain forest, tropical dry forest, tropical savanna, desert, temperate grassland, temperate woodland andshrubland, temperate forest, northwestern coniferous forest, boreal forest, and tundra. Each of thesebiomes is defined by a unique set of abiotic factors particularly climate and has a characteristicecological community.

2 The map shows the natural geographic distribution of these Major Biomes . Beaware, however; that this is just one of many different systems that are used to classify Biomes . Themap does not take into account changes made by human boundaries between the Biomes may appear to be sharp on the map. On the ground, however,there are often transitional areas between Biomes . In these transitional areas, one biome's plants andanimals gradually become less frequent, while the organisms characteristic of the adjacent biomebecome more frequent. In addition, the community structure of a particular biome will differ slightly,depending on location and elevation above sea level.

3 For this survey, you will study an example ofeach Major biome from a specific location and elevation. You will begin in the tropics and finish atthe Rain ForestTropical rain forests arehome to more species thanall other land Biomes com-bined. The leafy tops of talltrees extending up to 70meters above the forestfloor form a dense cover-ing called a canopy. In theshade below the canopy, asecond layer of shortertrees and vines forms anunderstory. Organic matterthat falls to the forest floorquickly decomposes andthe nutrients are Abiotic factors:hot and wet year-round; thin, nutrient-poor soils Dominant plants:broad-leaved evergreen trees; ferns; large woody vines andclimbing plants; orchids and bromeliads Dominant wildlife:herbivores such as sloths, tapirs, and capybaras; predatorssuch as jaguars; anteaters; monkeys; birds such as toucans, parrots, and parakeets;insects such as butterflies, ants, and beetles; piranhas and other freshwater fishes.

4 Reptiles such as frogs, caymans, boa constrictors, and anacondas Geographic distribution:parts of South and Central America, Southeast Asia,parts of Africa, southern India, and northeastern AustraliaTropical Dry ForestTropical dry forests grow inplaces where rainfall ishighly seasonal rather thanyear-round. During the dryseason, nearly all the treesdrop their leaves to con-serve water. A tree thatsheds its leaves during aparticular season each yearis called Abiotic factors:generally warm year-round; alternating wet and dry seasons; richsoils subject to erosion Dominant plants:tall, deciduous trees that form a dense canopy during the wetseason; drought-tolerant orchids and bromeliads; aloes and other succulents Dominant wildlife:tigers; monkeys; herbivores such as elephants, Indian rhinoc-eros, hog deer ; birds such as great pied hornbill, pied harrier, and spot-billed peli-can; insects such as termites.

5 Reptiles such as snakes and monitor lizards Geographic distribution:parts of Africa, South and Central America, Mexico,India, Australia, and tropical islandsTropical SavannaReceiving more seasonalrainfall than deserts butless than tropical dryforests, tropical savannas,or grasslands, are charac-terized by a cover of grass-es. Savannas are spottedwith isolated trees andsmall groves of trees andshrubs. Compact soils, fair-ly frequent fires, and theaction of large animalssuch as rhinoceros preventsome savanna areas fromturning into dry Abiotic factors: warm temperatures; seasonal rainfall; compact soil; frequentfires set by lightning Dominant plants:tall, perennial grasses; sometimes drought-tolerant and fire-resistant trees or shrubs Dominant wildlife:predators such as lions, leopards, cheetahs, hyenas, and jack-als; aardvarks; herbivores such as elephants, giraffes, antelopes, and zebras;baboons; birds such as eagles, ostriches, weaver birds, and storks.

6 Insects such astermites Geographic distribution:large parts of eastern Africa, southern Brazil, northernAustraliaDesertAll deserts are dry - infact, a desert biome isdefined as having annualprecipitation of less than 25centimeters. Beyond that,deserts vary greatly,depending on elevation andlatitude. Many undergoextreme temperaturechanges during the courseof a day, alternatingbetween hot and cold. Theorganisms in this biomecan tolerate the Abiotic factors:low precipitation, variable temperatures; soils rich in minerals butpoor in organic material Dominant plants:cacti and other succulents; creosote bush and other plants withshort growth cycles Dominant wildlife: predators such as mountain lions, gray foxes, and bobcats;herbivores such as mule deer , pronghorn antelope, desert bighorn sheep, and kan-garoo rats; bats; birds such as owls, hawks, and roadrunners; insects such as ants,beetles, butterflies, flies, and wasps.

7 Reptiles such as tortoises, rattlesnakes, andlizards Geographic distribution: Africa, Asia, the Middle East, United States, Mexico,South America, and AustraliaTemperate GrasslandCharacterized by a rich mixof grasses and underlaid bysome of the world's mostfertile soils, temperategrasslands such as plainsand prairies once coveredvast areas of the midwest-ern United States. Since thedevelopment of the steelplow, however, most havebeen converted to agricul-tural fields. Periodic firesand heavy grazing by largeherbivores maintain thecharacteristic plant Abiotic factors:warm to hot summers; cold winters; moderate, seasonal precipi-tation; fertile soils; occasional fires Dominant plants:lush, perennial grasses and herbs; most are resistant todrought, fire, and cold Dominant wildlife:predators such as coyotes and badgers -- historically includedwolves and grizzly bears; herbivores such as mule deer , pronghorn antelope, rab-bits, prairie dogs, and introduced cattle -- historically included bison.

8 Birds suchas hawks, owls, bobwhite, prairie chicken, mountain plover; reptiles such assnakes; insects such as ants and grasshoppers Geographic distribution:central Asia, North America, Australia, central Europe,and upland plateaus of South AmericaTemperate Woodland and ShrublandThis biome is characterizedby a semiarid climate and amix of shrub communitiesand open woodlands. In theopen woodlands, largeareas of grasses and wild-flowers such as poppies areinterspersed with oak that are dom-inated by shrubs are alsoknown as chaparral. Thegrowth of dense, low plantsthat contain flammable oilsmakes fires a Abiotic factors:hot, dry summers; cool, moist winters; thin, nutrient-poor soils;periodic fires Dominant plants:woody evergreen shrubs with small, leathery leaves; fragrant,oily herbs that grow during winter and die in summer Dominant wildlife:predators such as coyotes, foxes, bobcats, and mountainlions; herbivores such as blacktailed deer , rabbits, squirrels, and mice; birds suchas hawks, California quail, western scrub jay, warblers and other songbirds; rep-tiles such as lizards and snakes.

9 Butterflies; spiders Geographic distribution:western coasts of North and South America, areasaround the Mediterranean Sea, South Africa, and AustraliaTemperate ForestTemperate forests contain amixture of deciduous andconiferous (koh-NIF-ur-us)trees. Coniferous trees, orconifers, produce seed-bear-ing cones and most haveleaves shaped like forests have coldwinters that halt plantgrowth for several autumn, the deciduoustrees shed their leaves. Inthe spring, small plantsburst out of the ground andflower. Soils of temperateforests are often rich inhumus (HYOO-mus), amaterial formed fromdecaying leaves and otherorganic matter that makessoil Abiotic factors:cold to moderate winters; warm summers; year-round precipita-tion; fertile soils Dominant plants:broadleaf deciduous trees; some conifers; flowering shrubs;herbs; a ground layer of mosses and ferns Dominant wildlife: deer ; black bears; bobcats; nut and acorn feeders, such assquirrels; omnivores such as raccoons and skunks; numerous songbirds; turkeys Geographic distribution:eastern United States.

10 Southeastern Canada; most ofEurope; and parts of Japan, China, and AustraliaNorthwestern Coniferous ForestMild, moist air from thePacific Ocean providesabundant rainfall to thisbiome. The forest is madeup of a variety of conifers,ranging from giant red-woods, along the coast ofnorthern Cal