Land BiomesLand Biomes

Introduction Introduction

Biomes are the major regional Biomes are the major regional groupings of plants and animals groupings of plants and animals discernible at a global scalediscernible at a global scale

distribution patterns are correlated distribution patterns are correlated with regional climate patterns and with regional climate patterns and identified according to the climax identified according to the climax vegetation typevegetation type

Major BiomesMajor Biomes

DesertsDeserts

ForestsForests

GrasslandsGrasslands

TundraTundra

AquaticAquatic

DesertsDesertsDeserts cover about one fifth of the Deserts cover about one fifth of the Earth’s surface and occur where rainfall Earth’s surface and occur where rainfall is less than 25 cm/yearis less than 25 cm/year

Most deserts occur at low latitudesMost deserts occur at low latitudes

Most deserts have a considerable Most deserts have a considerable amount of specialized vegetation, as well amount of specialized vegetation, as well as specialized vertebrate and as specialized vertebrate and invertebrate animalsinvertebrate animals

DesertsDesertsSoils often have abundant nutrients Soils often have abundant nutrients because they need only water to become because they need only water to become very productive and have little or no organic very productive and have little or no organic mattermatter

Disturbances are common in the form of Disturbances are common in the form of occasional fires or cold weather, and occasional fires or cold weather, and sudden, infrequent, but intense rains that sudden, infrequent, but intense rains that cause floodingcause flooding

Types of DesertsTypes of Deserts

Hot and DryHot and Dry

SemiaridSemiarid

CoastalCoastal

ColdCold

Hot and Dry DesertHot and Dry DesertTemperatureDesert surfaces receive a little more than twice

the solar radiation received by humid regions and lose almost twice as much heat at night

Many mean annual temperatures range from 20-25° C

The extreme maximum ranges from 43.5-49° C. Minimum temperatures sometimes drop to -18° C

Hot and Dry DesertHot and Dry DesertPrecipitation Rainfall is usually very low and/or concentrated in short

bursts between long rainless periods Evaporation rates regularly exceed rainfall rates Sometimes rain starts falling and evaporates before

reaching the ground Rainfall is lowest on the Atacama Desert of Chile, where

it averages less than 1.5 cm Inland Sahara also receives less than 1.5 cm a year Rainfall in American deserts is higher—almost 28 cm a

year

Hot and Dry DesertHot and Dry DesertPlants

Canopy in most deserts is very rarePlants are mainly ground-hugging shrubs and short woody trees

Leaves are “replete” (fully supported with nutrients) with water-conserving characteristicsThey tend to be small, thick and covered with a thick cuticle (outer layer)In the cacti, the leaves are much-reduced (to spines) and photosynthetic activity is restricted to the stemsSome plants open their stomata only at night when evaporation rates are lowest

Hot and Dry DesertHot and Dry Desert

Yuccas Ocotillo Turpentine bush Prickly Pears False mesquite

Sotol Ephedras

Agaves Brittlebush

Hot and Dry Hot and Dry DesertDesertAnimalsAnimals

The animals include small nocturnal The animals include small nocturnal carnivorescarnivoresThe dominant animals are burrowers There The dominant animals are burrowers There are also insects, arachnids, reptiles and are also insects, arachnids, reptiles and birdsbirdsThe animals stay inactive in protected The animals stay inactive in protected hideaways during the hot day and come out hideaways during the hot day and come out to forage at dusk, dawn or at night, when to forage at dusk, dawn or at night, when the desert is coolerthe desert is cooler

SnakesSnakes

LizardsLizards

Tortoise Tortoise Bighorn Sheep Bighorn Sheep

CoyoteCoyote Ants Ants

TarantulaTarantulaTarantula Wasp Tarantula Wasp

Semiarid DesertSemiarid DesertTemperatureTemperature

The summers are moderately long and dry, The summers are moderately long and dry, and like hot deserts, the winters normally and like hot deserts, the winters normally bring low concentrations of rainfallbring low concentrations of rainfallSummer temperatures usually average Summer temperatures usually average between 21-27° Cbetween 21-27° CIt normally does not go above 38° C and It normally does not go above 38° C and evening temperatures are cool, at around evening temperatures are cool, at around 10° C. 10° C.

Semiarid DesertSemiarid DesertPrecipitationCool nights help both plants and animals by

reducing moisture loss from transpiration, sweating and breathing

Condensation of dew caused by night cooling may equal or exceed the rainfall received by some deserts

As in the hot desert, rainfall is often very low and/or concentrated

Semiarid DesertSemiarid DesertPlantsThe spiny nature of many plants in semiarid deserts

provides protection in a hazardous environmentThe large numbers of spines shade the surface

enough to significantly reduce transpirationThe same may be true of the hairs on the woolly

desert plantsMany plants have silvery or glossy leaves, allowing

them to reflect more radiant energyThese plants often have an unfavorable odor or

taste.

Semiarid DesertSemiarid DesertCreosote bush

Bur sage

White thorn

Cat claw

Mesquite

Brittle bushes

Lyciums

Jujube

Semiarid DesertSemiarid Desert

AnimalsAnimalsDuring the day, insects move around twigs to During the day, insects move around twigs to

stay on the shady side; jack rabbits follow the stay on the shady side; jack rabbits follow the moving shadow of a cactus or shrubmoving shadow of a cactus or shrub

Naturally, many animals find protection in Naturally, many animals find protection in underground burrows where they are underground burrows where they are insulated from both heat and aridityinsulated from both heat and aridity

Semiarid DesertSemiarid DesertKangaroo rats

Rabbits Skunks

Side-blotched Lizard Mountain Lion

Mule Deer Rattlesnake Burrowing owls Western Bluebird

Types of ForestsTypes of Forests

Tropical Tropical

Temperate Temperate

Boreal forests (taiga) Boreal forests (taiga)

Tropical ForestsTropical Forestsare characterized by the greatest diversity of are characterized by the greatest diversity of speciesspecies

occur near the equator, within the area bounded occur near the equator, within the area bounded by latitudes 23.5 degrees N and 23.5 degrees Sby latitudes 23.5 degrees N and 23.5 degrees S

distinct seasonalitydistinct seasonalitywinter is absentwinter is absent

only two seasons are present (rainy and dry)only two seasons are present (rainy and dry)

The length of daylight is 12 hours and varies The length of daylight is 12 hours and varies little. little.

Tropical ForestsTropical Forests

Tropical ForestsTropical Forests

TemperatureTemperature

average 20-25° C and varies little average 20-25° C and varies little throughout the yearthroughout the year

the average temperatures of the three the average temperatures of the three warmest and three coldest months do not warmest and three coldest months do not differ by more than 5 degreesdiffer by more than 5 degrees

Tropical ForestsTropical Forests

PrecipitationPrecipitationevenly distributed throughout the yearevenly distributed throughout the year

annual rainfall exceeds 2 meters annual rainfall exceeds 2 meters

Tropical ForestsTropical Forests

SoilSoilnutrient-poor and acidicnutrient-poor and acidic

decomposition is rapiddecomposition is rapid

subject to heavy leachingsubject to heavy leaching

Tropical ForestsTropical ForestsPlantsPlants

Canopy Canopy multilayered multilayered ContinuousContinuousallows little light penetrationallows little light penetration

Flora is highly diverseFlora is highly diverseone square kilometer may contain as many as 100 one square kilometer may contain as many as 100 different tree speciesdifferent tree species

Trees are 25-35 m tallTrees are 25-35 m tall buttressed trunks and shallow rootsbuttressed trunks and shallow rootsmostly evergreen, with large dark green leaves. mostly evergreen, with large dark green leaves.

Tropical ForestsTropical Forests

Plant AdaptationsPlant Adaptationsability to tolerate constant shade ability to tolerate constant shade

adapt strategies to reach sunlightadapt strategies to reach sunlight

Fungus is a good example of a plant that Fungus is a good example of a plant that flourishes in warm, dark places created by flourishes in warm, dark places created by the forest canopy and understory the forest canopy and understory

Tropical ForestsTropical Forests LianasLianas Epiphytes Epiphytes (grow on another plant)(grow on another plant)

FernsFerns

Moss Moss

CurareCurareForest CanopyForest Canopy Palms Palms

Tropical ForestsTropical Forests White-faced MonkeyWhite-faced Monkey Tree frogTree frog ToucanToucan

Vine SnakeVine Snake GeckoGecko Vested AnteaterVested Anteater Transparent butterflyTransparent butterfly

JaguarJaguar Unicorn grasshopperUnicorn grasshopper Red-eyed tree frogRed-eyed tree frog Silver-throated TanagerSilver-throated Tanager

Tropical king snakeTropical king snake ScorpionScorpion

http://curriculum.calstatela.edu/courses/builders/lessons/less/biomes/deciduous/decweb.html

Temperate ForestTemperate ForestTemperatureTemperature

Well-defined seasons with a distinct winter Well-defined seasons with a distinct winter characterize this forest biomecharacterize this forest biome

Moderate climate and a growing season of Moderate climate and a growing season of 140-200 days during 4-6 frost-free months 140-200 days during 4-6 frost-free months distinguish temperate forestsdistinguish temperate forests

Temperature varies from -30° C to 30° C.Temperature varies from -30° C to 30° C.

Temperate ForestTemperate Forest

Temperate ForestTemperate ForestPrecipitationPrecipitation

(75-150 cm) is distributed evenly throughout (75-150 cm) is distributed evenly throughout the yearthe year

SoilsSoilsfertile, enriched with decaying litterfertile, enriched with decaying litter

Temperate ForestTemperate ForestPlantsPlants

Canopy Canopy moderately dense moderately dense allows light to penetrateallows light to penetrateresulting in well-developed and richly diversified resulting in well-developed and richly diversified understory vegetation and stratification of animalsunderstory vegetation and stratification of animals

Flora is characterized by 3-4 tree species per Flora is characterized by 3-4 tree species per square kilometersquare kilometerTrees are distinguished by broad leaves that are Trees are distinguished by broad leaves that are lost annuallylost annually

Temperate ForestTemperate ForestOakOak HickoryHickory BeechBeechHemlockHemlock MapleMaple BasswoodBasswoodCottonwoodCottonwood ElmElm Willow Spring-flowering herbsWillow Spring-flowering herbs

Bank VoleBank Vole

Black BearBlack Bear

Gray SquirrelGray Squirrel

RaccoonRaccoon

White-tailed Deer White-tailed Deer

Wild BoarWild Boar

CardinalCardinal

GoshawkGoshawk

TurkeyTurkey

Yellow-bellied Sapsucker Yellow-bellied Sapsucker

Rat Snake Rat Snake

Spring PeeperSpring Peeper

Temperate Temperate ForestForest

Boreal forests, or taigaBoreal forests, or taigarepresent the largest terrestrial biomerepresent the largest terrestrial biomeOccurs between 50 and 60 degrees Occurs between 50 and 60 degrees north latitudesnorth latitudesseasons are divided into short, moist, seasons are divided into short, moist, and moderately warm summers and and moderately warm summers and long, cold, and dry winterslong, cold, and dry winterslength of the growing season in boreal length of the growing season in boreal forests is 130 days forests is 130 days

Boreal forests, or taigaBoreal forests, or taiga

Boreal forests, or taigaBoreal forests, or taigaTemperatures are very lowTemperatures are very low

Precipitation is primarily in the form of Precipitation is primarily in the form of snow, 40-100 cm annuallysnow, 40-100 cm annually

Soil is thin, nutrient-poor, and acidicSoil is thin, nutrient-poor, and acidic

Canopy permits low light penetration, Canopy permits low light penetration, and as a result, understory is limitedand as a result, understory is limited

Boreal forests, or taigaBoreal forests, or taigaThe conical or spire-shaped needleleaf trees common to the taiga The conical or spire-shaped needleleaf trees common to the taiga are adapted to the cold and the physiological drought of winter and are adapted to the cold and the physiological drought of winter and to the short-growing season: to the short-growing season:

Conical shape - promotes shedding of snow and prevents loss of branches. Conical shape - promotes shedding of snow and prevents loss of branches.

Needleleaf - narrowness reduces surface area (transpired), especially during Needleleaf - narrowness reduces surface area (transpired), especially during winter when the frozen ground prevents plants from replenishing their water winter when the frozen ground prevents plants from replenishing their water supply. The needles of boreal conifers also have thick waxy coatings--a supply. The needles of boreal conifers also have thick waxy coatings--a waterproof cuticle--in which stomata are sunken and protected from drying waterproof cuticle--in which stomata are sunken and protected from drying winds. winds.

Evergreen habit - retention of foliage allows plants to photosynthesize as Evergreen habit - retention of foliage allows plants to photosynthesize as soon as temperatures permit in spring, rather than having to waste time in the soon as temperatures permit in spring, rather than having to waste time in the short growing season merely growing leaves. short growing season merely growing leaves.

Dark color - the dark green of spruce and fir needles helps the foliage absorb Dark color - the dark green of spruce and fir needles helps the foliage absorb maximum heat from the sun and begin photosynthesis as early as possiblemaximum heat from the sun and begin photosynthesis as early as possible

Taiga Taiga PlantsPlantsBalsam FirBalsam Fir

Black Spruce Douglas-fir Black Spruce Douglas-fir

Paper Birch Eastern Red Cedar Jack PinePaper Birch Eastern Red Cedar Jack Pine

Siberian White Fir White Poplar Siberian White Fir White Poplar

SpruceSpruce

White Spruce White Spruce

Taiga AnimalsTaiga Animals

American Black Bear Bald Eagle American Black Bear Bald Eagle Bobcat Bobcat

Canadian Lynx Gray Wolf Grizzly Bear Canadian Lynx Gray Wolf Grizzly Bear

Long-Eared Owl Red Fox River Otter Long-Eared Owl Red Fox River Otter

Snowshoe Rabbit Wolverine Snowshoe Rabbit Wolverine

Boreal Boreal forests, forests, or taigaor taiga

GrasslandsGrasslandscharacterized as lands dominated by characterized as lands dominated by grasses rather than large shrubs or treesgrasses rather than large shrubs or trees

largest land animals due to huge largest land animals due to huge vegetationvegetation

There are two main divisions of There are two main divisions of grasslandsgrasslands

tropical grasslands called savannastropical grasslands called savannas

temperate grasslands. temperate grasslands.

SavannaSavannaSavanna is grassland with scattered individual Savanna is grassland with scattered individual treestreesClimate is the most important factor in creating a Climate is the most important factor in creating a savannasavannafires maintain an area as a savanna fires maintain an area as a savanna Types of Savannas Types of Savannas

climatic conditions are called climatic conditions are called climatic savannasclimatic savannassoil conditions not entirely maintained by fire are soil conditions not entirely maintained by fire are called called edaphic savannasedaphic savannasderived savannaderived savanna is the result of people clearing forest is the result of people clearing forest land for cultivation land for cultivation

SavannaSavanna

SavannaSavannaPrecipitationPrecipitation

always found in warm or hot climates where the always found in warm or hot climates where the annual rainfall is from about 50.8 to 127 cm (20-50 annual rainfall is from about 50.8 to 127 cm (20-50 inches) per yearinches) per year

crucial that the rainfall is concentrated in six or crucial that the rainfall is concentrated in six or eight months of the year, followed by a long eight months of the year, followed by a long period of drought when fires can occurperiod of drought when fires can occur

if the rain were well distributed throughout the if the rain were well distributed throughout the year, many such areas would become tropical year, many such areas would become tropical forestforest

SavannaSavannaPlantsPlants

characterized by a continuous cover of characterized by a continuous cover of perennial grasses, often 3 to 6 feet tall at perennial grasses, often 3 to 6 feet tall at maturitymaturity

may or may not also have an open canopy may or may not also have an open canopy of drought-resistant, fire-resistant, or of drought-resistant, fire-resistant, or browse-resistant trees, or they may have an browse-resistant trees, or they may have an open shrub layeropen shrub layer

SavannaSavannaAnimalsAnimals

When the rains come, savanna bunch grasses When the rains come, savanna bunch grasses grow vigorouslygrow vigorously

larger grasses may grow an inch or more in 24 larger grasses may grow an inch or more in 24 hourshours

a surge of new life at this timea surge of new life at this time

for example, many antelope calves are bornfor example, many antelope calves are bornwith so much grass to feed on, mothers have plenty with so much grass to feed on, mothers have plenty of milkof milk

calves die if the rains fail to come. calves die if the rains fail to come.

SavannaSavannaAnimalsAnimals

do not all occur in the same savannado not all occur in the same savannagiraffes, zebras, buffaloes, kangaroos, mice, giraffes, zebras, buffaloes, kangaroos, mice, moles, gophers, ground squirrels, snakes, moles, gophers, ground squirrels, snakes, worms, termites, beetles, lions, leopards, worms, termites, beetles, lions, leopards, hyenas, and elephantshyenas, and elephants

GiraffesGiraffes ZebrasZebras Water buffaloesWater buffaloes

CheetahCheetah Baboon Baboon AntsAnts

CrocodileCrocodile Wild DogWild Dog Termites Termites

MeerkatsMeerkats LionsLions LeopardsLeopards

HyenasHyenas ElephantsElephants RhinocerosRhinoceros

Temperate GrasslandTemperate Grasslandgrasses as the dominant vegetation grasses as the dominant vegetation with trees and large shrubs absentwith trees and large shrubs absent

seasonal drought and occasional seasonal drought and occasional fires are very important to fires are very important to biodiversity. biodiversity.

effects aren’t as dramatic in temperate effects aren’t as dramatic in temperate grasslands as they are in savannas grasslands as they are in savannas

Temperate GrasslandTemperate GrasslandPrecipitationPrecipitation

usually occurs in the late spring and early usually occurs in the late spring and early summersummer

annual average is about 50.8 to 88.9 cm annual average is about 50.8 to 88.9 cm (20-35 inches). (20-35 inches).

Temperate GrasslandTemperate Grassland

Temperate GrasslandTemperate GrasslandTemperatureTemperature

range is very large over the course of the range is very large over the course of the yearyear

summer temperatures can be well over 38° C summer temperatures can be well over 38° C (100 degrees Fahrenheit(100 degrees Fahrenheit

winter temperatures can be as low as -40° C winter temperatures can be as low as -40° C (-40 degrees Fahrenheit)(-40 degrees Fahrenheit)

Temperate GrasslandTemperate GrasslandSoilSoil

deep and dark, with fertile upper layersdeep and dark, with fertile upper layers

nutrient-rich from the growth and decay nutrient-rich from the growth and decay of deep, many-branched grass rootsof deep, many-branched grass roots

rotted roots hold the soil together and rotted roots hold the soil together and provide a food source for living plants provide a food source for living plants

Temperate GrasslandTemperate GrasslandPlantsPlants

different species of grass grows best in a different species of grass grows best in a particular grassland environment particular grassland environment seasonal drought, occasional fires, and seasonal drought, occasional fires, and grazing by large mammals all prevent woody grazing by large mammals all prevent woody shrubs and trees from invading and becoming shrubs and trees from invading and becoming establishedestablisheda few trees, such as cottonwoods, oaks, and a few trees, such as cottonwoods, oaks, and willows grow in river valleys, and some willows grow in river valleys, and some nonwoody plants, specifically a few hundred nonwoody plants, specifically a few hundred species of flowers, grow among the grassesspecies of flowers, grow among the grasses

Temperate GrasslandTemperate GrasslandPurple needlegrass Blue GramaPurple needlegrass Blue Grama

Buffalo grass GalletaBuffalo grass Galleta

Asters Blazing StarsAsters Blazing Stars

Coneflowers GoldenrodsConeflowers Goldenrods

Sunflowers CloversSunflowers Clovers

Psoraleas Wild Indigos Psoraleas Wild Indigos

Temperate GrasslandTemperate GrasslandAnimalsAnimals

gazelles, zebras, rhinoceroses, wild gazelles, zebras, rhinoceroses, wild horses, lions, wolves, prairie dogs, jack horses, lions, wolves, prairie dogs, jack rabbits, deer, mice, coyotes, foxes, rabbits, deer, mice, coyotes, foxes, skunks, badgers, blackbirds, grouses, skunks, badgers, blackbirds, grouses, meadowlarks, quails, sparrows, hawks, meadowlarks, quails, sparrows, hawks, owls, snakes, grasshoppers, leafhoppers, owls, snakes, grasshoppers, leafhoppers, and spidersand spiders

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

coldest of all the biomescoldest of all the biomescomes from the Finnish word comes from the Finnish word tunturiatunturia, , meaning treeless plainmeaning treeless plainfrost-molded landscapesfrost-molded landscapesextremely low temperaturesextremely low temperatureslittle precipitationlittle precipitationpoor nutrientspoor nutrients short growing seasonsshort growing seasons

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

TemperatureTemperaturegrowing season ranges from 50 to 60 daysgrowing season ranges from 50 to 60 days

average winter temperature is -34° C (-30° F)average winter temperature is -34° C (-30° F)

average summer temperature is 3-12° C (37-average summer temperature is 3-12° C (37-54° F) which enables this biome to sustain 54° F) which enables this biome to sustain lifelife

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

PrecipitationPrecipitation

may vary in different regions of the may vary in different regions of the arcticarctic

yearly precipitation, including melting yearly precipitation, including melting snow, is 15 to 25 cm (6 to 10 inches) snow, is 15 to 25 cm (6 to 10 inches)

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

SoilSoilformed slowlyformed slowly

layer of permanently frozen subsoil called permafrost layer of permanently frozen subsoil called permafrost exists, consisting mostly of gravel and finer materialexists, consisting mostly of gravel and finer material

when water saturates the upper surface, bogs and ponds when water saturates the upper surface, bogs and ponds may form, providing moisture for plantsmay form, providing moisture for plants

no deep root systems in the vegetation of the arctic no deep root systems in the vegetation of the arctic tundra, however, there are still a wide variety of plants tundra, however, there are still a wide variety of plants that are able to resist the cold climate that are able to resist the cold climate

TundraTundra: The Not-So Barren Land : The Not-So Barren Land There are about 1,700 kinds of plants in the arctic There are about 1,700 kinds of plants in the arctic and subarcticand subarcticadapted to sweeping winds and disturbances of the adapted to sweeping winds and disturbances of the soilsoilshort and group together to resist the cold short and group together to resist the cold temperatures and are protected by the snow during temperatures and are protected by the snow during the winterthe wintercarry out photosynthesis at low temperatures and carry out photosynthesis at low temperatures and low light intensitieslow light intensitiesgrowing seasons are short and most plants growing seasons are short and most plants reproduce by budding and division rather than reproduce by budding and division rather than sexually by floweringsexually by flowering

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

low shrubs, sedges, reindeer mosses, low shrubs, sedges, reindeer mosses, liverworts, and grasses liverworts, and grasses

400 varieties of flowers 400 varieties of flowers

crustose and foliose lichen crustose and foliose lichen

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

AnimalsAnimals

Strategies evolved to withstand the Strategies evolved to withstand the harsh conditions of the tundra can be harsh conditions of the tundra can be divided among those species that are divided among those species that are resident and those that are migratoryresident and those that are migratory

TundraTundra: The Not-So Barren Land : The Not-So Barren Land ResidentResident

small number of bird (e.g., ptarmigan) and mammal (e.g., muskox, small number of bird (e.g., ptarmigan) and mammal (e.g., muskox, arctic hare, arctic fox, musk ox) arctic hare, arctic fox, musk ox) Morphological adaptations Morphological adaptations

large, compact bodieslarge, compact bodiesa thick insulating cover of feathers or fur a thick insulating cover of feathers or fur pelage and plumage that turns white in winter, brown in summerpelage and plumage that turns white in winter, brown in summer

Physiological adaptations Physiological adaptations ability to accumulate thick deposits of fat during the short growing seasonability to accumulate thick deposits of fat during the short growing seasoninsulation and as a store of energy for use during the winter, when animal insulation and as a store of energy for use during the winter, when animal species remain activespecies remain active

Population adaptations Population adaptations cyclical fluctuations in population size, best seen perhaps in the lemming, a cyclical fluctuations in population size, best seen perhaps in the lemming, a small rodent which is the major herbivore in the tundra's simple food chainsmall rodent which is the major herbivore in the tundra's simple food chainpredator populations and plant populations respond in kind to the peaks predator populations and plant populations respond in kind to the peaks and crashes of the herbivore populationsand crashes of the herbivore populations

TundraTundra: The Not-So Barren Land : The Not-So Barren Land

MigratoryMigratoryspecies such as waterfowl, shorebirds and species such as waterfowl, shorebirds and caribou adapt to the tundra by avoiding the caribou adapt to the tundra by avoiding the most severe conditions of wintermost severe conditions of wintereach year at the end of the short growing each year at the end of the short growing season they move southward into the boreal season they move southward into the boreal forest or beyond, but return to the tundra to forest or beyond, but return to the tundra to breed due to the long growing seasonbreed due to the long growing season