2IntroductionBiomes are the major regional groupings of plants and animals discernible at a global scaledistribution patterns are correlated with regional climate patterns and identified according to the climax vegetation typea biome is composed not only of the climax vegetation, but also of immature communities
3To understand the nature of biomes one needs to learn Global distribution patternWhere each biome is found and how each varies geographicallyA given biome may be composed of different taxa on different continents
4To understand the nature of biomes one needs to learn The dominant, characteristic, and unique growth formsvertical stratificationleaf shape, size, and habitspecial adaptations of the vegetation
5To understand the nature of biomes one needs to learn The types of animals (especially vertebrates) characteristic of the biomeTheir typical morphological, physiological, and/or behavioral adaptations to the environment
7DesertsDeserts cover about one fifth of the Earth’s surface and occur where rainfall is less than 50 cm/yearMost deserts occur at low latitudesAnother kind of desert, cold deserts, occur in the basin and mountain rangesMost deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals
8DesertsSoils often have abundant nutrients because they need only water to become very productive and have little or no organic matterDisturbances are common in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding
12Hot and Dry Desert Temperature Desert surfaces receive a little more than twice the solar radiation received by humid regions and lose almost twice as much heat at nightMany mean annual temperatures range from 20-25° CThe extreme maximum ranges from ° C. Minimum temperatures sometimes drop to -18° C
13Hot and Dry Desert Precipitation Rainfall is usually very low and/or concentrated in short bursts between long rainless periodsEvaporation rates regularly exceed rainfall ratesSometimes rain starts falling and evaporates before reaching the groundRainfall is lowest on the Atacama Desert of Chile, where it averages less than 1.5 cmInland Sahara also receives less than 1.5 cm a yearRainfall in American deserts is higher—almost 28 cm a year
14Hot and Dry Desert Soils Soils are course-textured, shallow, rocky or gravely with good drainage and have no subsurface waterThey are coarse because there is less chemical weatheringThe finer dust and sand particles are blown elsewhere, leaving heavier pieces behind
15Hot and Dry Desert Plants Canopy in most deserts is very rare Plants are mainly ground-hugging shrubs and short woody treesLeaves 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 (microscopic openings in the epidermis of leaves that allow for gas exchange) only at night when evaporation rates are lowest
16Hot and Dry Desert Yuccas Ocotillo Turpentine bush Prickly Pears False mesquiteSotolEphedrasAgavesBrittlebush
17Hot and Dry Desert Animals The animals include small nocturnal (active at night) carnivoresThe dominant animals are burrowers and kangaroo ratsThere are also insects, arachnids, reptiles and birdsThe animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler
18SnakesLizardsTortoise Bighorn SheepCoyote AntsTarantula Tarantula Wasp
19Semiarid Desert Temperature The summers are moderately long and dry, and like hot deserts, the winters normally bring low concentrations of rainfallSummer temperatures usually average between 21-27° CIt normally does not go above 38° C and evening temperatures are cool, at around 10° C.
20Semiarid Desert Precipitation Cool nights help both plants and animals by reducing moisture loss from transpiration, sweating and breathingCondensation of dew caused by night cooling may equal or exceed the rainfall received by some desertsAs in the hot desert, rainfall is often very low and/or concentratedThe average rainfall ranges from 2-4 cm annually.
21Semiarid DesertSoilsranges from sandy and fine-textured to loose rock fragments, gravel or sandfairly low salt concentration, compared to deserts which receive a lot of rain (acquiring higher salt concentrations as a result)there is no subsurface water.
22Semiarid Desert Plants The 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.
23Semiarid Desert Creosote bush Bur sage White thorn Cat claw Mesquite Brittle bushesLyciumsJujube
24Semiarid Desert Animals During the day, insects move around twigs to stay on the shady side; jack rabbits follow the moving shadow of a cactus or shrubNaturally, many animals find protection in underground burrows where they are insulated from both heat and aridity
26Coastal Desert Temperature The cool winters of coastal deserts are followed by moderately long, warm summersThe average summer temperature ranges from 13-24° C; winter temperatures are 5° C or belowThe maximum annual temperature is about 35° C and the minimum is about -4° CIn Chile, the temperature ranges from -2 to 5° C in July and 21-25° C in January
27Coastal Desert Precipitation The average rainfall measures 8-13 cm in many areasThe maximum annual precipitation over a long period of years has been 37 cm with a minimum of 5 cm
28Coastal Desert Soils fine-textured with a moderate salt content fairly porous with good drainage.
29Coastal DesertPlantsextensive root systems close to the surface where they can take advantage of any rain showersthick and fleshy leaves or stems can take in large quantities of water when it is available and store it for future usesome surfaces are corrugated with longitudinal ridges and groovesstem swells so that the grooves are shallow and the ridges far apartthe stem shrinks as water is used so that the grooves are deep and ridges close together.
30Coastal Desert Salt bush Buckwheat Bush Black bush Rice grass Little Leaf HorsebrushBlack SageChrysothamnus
31Coastal Desert Animals Some animals have specialized adaptations for dealing with the desert heat and lack of watertoads seal themselves in burrows with gelatinous secretions and remain inactive for eight or nine months until a heavy rain occursamphibians that pass through larval stages have accelerated life cycles, which improves their chances of reaching maturity before the waters evaporateinsects lay eggs that remain dormant until the environmental conditions are suitable for hatchingfairy shrimps also lay dormant eggs.
33Cold Desert Temperature Cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summerAntarctic, Greenland and the Nearctic realmshort, moist, and moderately warm summers with fairly long, cold wintersmean winter temperature is between -2 to 4° C and the mean summer temperature is between 21-26° C
34Cold Desert Precipitation winters receive quite a bit of snow mean annual precipitation ranges from cmannual precipitation has reached a maximum of 46 cm and a minimum of 9 cmheaviest rainfall of the spring is usually in April or Mayrainfall can be heavy in autumn in some areas
35Cold Desert Soil heavy, silty, and salty relatively porous and drainage is good so that most of the salt has been leached out
36Cold Desert Plants widely scattered areas of shad-scale, about 10 percent of the ground is coveredsome areas of sagebush it approaches 85 percentheights vary between 15 cm and 122 cmdeciduous, most having spiny leaves
38Cold DesertAnimalspopulation density can range from individuals per hectareall except the jack rabbits are burrowersalso applies to carnivoresseveral lizards do some burrowing and moving of soildeer are found only in the winter
41Forestsoccupy approximately one-third of Earth’s land areaaccount for over two-thirds of the leaf area of land plantscontain about 70% of carbon present in living thingsare major casualties of deforestation, pollution, and industrial usageforest biomes are classified according to numerous characteristics, with seasonality being the most widely used
42Types of ForestsTropicalTemperateBoreal forests (taiga)
43Tropical Forestsare characterized by the greatest diversity of speciesoccur near the equator, within the area bounded by latitudes 23.5 degrees N and 23.5 degrees Sdistinct seasonalitywinter is absentonly two seasons are present (rainy and dry)The length of daylight is 12 hours and varies little.
46Tropical Forests Temperature average 20-25° C and varies little throughout the yearthe average temperatures of the three warmest and three coldest months do not differ by more than 5 degrees
47Tropical Forests Precipitation evenly distributed throughout the year annual rainfall exceeds 2 meters
48Tropical Forests Soil nutrient-poor and acidic decomposition is rapid subject to heavy leaching
49Tropical Forests Plants Canopy Flora is highly diverse multilayeredContinuousallows little light penetrationFlora is highly diverseone square kilometer may contain as many as 100 different tree speciesTrees are m tallbuttressed trunks and shallow rootsmostly evergreen, with large dark green leaves.
50Tropical Forests Plant Adaptations ability to tolerate constant shade adapt strategies to reach sunlightFungus is a good example of a plant that flourishes in warm, dark places created by the forest canopy and understory
51Tropical Forests Lianas Epiphytes (grow on another plant) Ferns Moss CurareForest Canopy Palms
52Tropical Forests White-faced Monkey Tree frog Toucan Vine Snake Gecko Vested AnteaterTransparent butterflyJaguarUnicorn grasshopperRed-eyed tree frogSilver-throated TanagerTropical king snakeScorpion
54Temperate Forest Temperature Well-defined seasons with a distinct winter characterize this forest biomeModerate climate and a growing season of days during 4-6 frost-free months distinguish temperate forestsTemperature varies from -30° C to 30° C.
57Temperate Forest Precipitation Soils ( cm) is distributed evenly throughout the yearSoilsfertile, enriched with decaying litter
58Temperate Forest Plants Canopy moderately denseallows light to penetrateresulting in well-developed and richly diversified understory vegetation and stratification of animalsFlora is characterized by 3-4 tree species per square kilometerTrees are distinguished by broad leaves that are lost annually
59Temperate Forest Oak Hickory Beech Hemlock Maple Basswood Cottonwood ElmWillow Spring-flowering herbs
62Temperate ForestFurther subdivisions of this group are determined by seasonal distribution of rainfall:moist conifer and evergreen broad-leaved forests: wet winters and dry summers (rainfall is concentrated in the winter months and winters are relatively mild)dry conifer forests: dominate higher elevation zones; low precipitation. Mediterranean forests: precipitation is concentrated in winter, less than 1000 mm per yeartemperate coniferous: mild winters, high annual precipitation (greater than 2000 mm)temperate broad-leaved rainforests: mild, frost-free winters, high precipitation (more than 1500 mm) evenly distributed throughout the yearOnly scattered remnants of original temperate forests remain
63Boreal forests, or taiga represent the largest terrestrial biomeOccurs between 50 and 60 degrees north latitudesseasons are divided into short, moist, and moderately warm summers and long, cold, and dry winterslength of the growing season in boreal forests is 130 days
66Boreal forests, or taiga Temperatures are very lowPrecipitation is primarily in the form of snow, cm annuallySoil is thin, nutrient-poor, and acidicCanopy permits low light penetration, and as a result, understory is limited
67Boreal forests, or taiga The conical or spire-shaped needleleaf trees common to the taiga are adapted to the cold and the physiological drought of winter and to the short-growing season:Conical shape - promotes shedding of snow and prevents loss of branches.Needleleaf - narrowness reduces surface area (transpired), especially during winter when the frozen ground prevents plants from replenishing their water supply. The needles of boreal conifers also have thick waxy coatings--a waterproof cuticle--in which stomata are sunken and protected from drying winds.Evergreen habit - retention of foliage allows plants to photosynthesize as soon as temperatures permit in spring, rather than having to waste time in the short growing season merely growing leaves.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 possible
68Taiga Plants Balsam Fir Black Spruce Douglas-fir Paper Birch Eastern Red Cedar Jack PineSiberian White Fir White PoplarSpruceWhite Spruce
69Taiga Animals American Black Bear Bald Eagle Bobcat Canadian Lynx Gray Wolf Grizzly BearLong-Eared Owl Red Fox River OtterSnowshoe Rabbit Wolverine
71Grasslandscharacterized as lands dominated by grasses rather than large shrubs or treeslargest land animals due to huge vegetationThere are two main divisions of grasslandstropical grasslands called savannastemperate grasslands.
72Savanna Savanna is grassland with scattered individual trees Climate is the most important factor in creating a savannafires maintain an area as a savannaTypes of Savannasclimatic conditions are called climatic savannassoil conditions not entirely maintained by fire are called edaphic savannasderived savanna is the result of people clearing forest land for cultivation
74Savanna Precipitation always found in warm or hot climates where the annual rainfall is from about 50.8 to 127 cm (20-50 inches) per yearcrucial that the rainfall is concentrated in six or eight months of the year, followed by a long period of drought when fires can occurif the rain were well distributed throughout the year, many such areas would become tropical forest
75Savanna Soils porous, with rapid drainage of water only a thin layer of humus (the organic portion of the soil created by partial decomposition of plant or animal matter), which provides vegetation with nutrients
76SavannaPlantscharacterized by a continuous cover of perennial grasses, often 3 to 6 feet tall at maturitymay or may not also have an open canopy of drought-resistant, fire-resistant, or browse-resistant trees, or they may have an open shrub layer
77SavannaAnimalsWhen the rains come, savanna bunch grasses grow vigorouslylarger grasses may grow an inch or more in 24 hoursa surge of new life at this timefor example, many antelope calves are bornwith so much grass to feed on, mothers have plenty of milkcalves die if the rains fail to come.
78Savanna Animals do not all occur in the same savanna giraffes, zebras, buffaloes, kangaroos, mice, moles, gophers, ground squirrels, snakes, worms, termites, beetles, lions, leopards, hyenas, and elephants
79Giraffes Zebras Water buffaloes Cheetah Baboon AntsCrocodile Wild Dog TermitesMeerkats Lions LeopardsHyenas Elephants Rhinoceros
80Temperate Grasslandgrasses as the dominant vegetation with trees and large shrubs absentseasonal drought and occasional fires are very important to biodiversity.effects aren’t as dramatic in temperate grasslands as they are in savannas
81Temperate Grassland Precipitation usually occurs in the late spring and early summerannual average is about 50.8 to 88.9 cm (20-35 inches).
84Temperate Grassland Temperature range is very large over the course of the yearsummer temperatures can be well over 38° C (100 degrees Fahrenheitwinter temperatures can be as low as -40° C (-40 degrees Fahrenheit)
85Temperate Grassland Soil deep and dark, with fertile upper layers nutrient-rich from the growth and decay of deep, many-branched grass rootsrotted roots hold the soil together and provide a food source for living plants
86Temperate Grassland Plants different species of grass grows best in a particular grassland environmentseasonal drought, occasional fires, and grazing by large mammals all prevent woody shrubs and trees from invading and becoming establisheda few trees, such as cottonwoods, oaks, and willows grow in river valleys, and some nonwoody plants, specifically a few hundred species of flowers, grow among the grasses
89Tundra: The Not-So Barren Land coldest of all the biomescomes from the Finnish word tunturia, meaning treeless plainfrost-molded landscapesextremely low temperatureslittle precipitationpoor nutrientsshort growing seasons
92Tundra: The Not-So Barren Land Temperaturegrowing season ranges from 50 to 60 daysaverage winter temperature is -34° C (-30° F)average summer temperature is 3-12° C (37-54° F) which enables this biome to sustain life
93Tundra: The Not-So Barren Land Precipitationmay vary in different regions of the arcticyearly precipitation, including melting snow, is 15 to 25 cm (6 to 10 inches)
94Tundra: The Not-So Barren Land Soilformed slowlylayer of permanently frozen subsoil called permafrost exists, consisting mostly of gravel and finer materialwhen water saturates the upper surface, bogs and ponds may form, providing moisture for plantsno deep root systems in the vegetation of the arctic tundra, however, there are still a wide variety of plants that are able to resist the cold climate
95Tundra: The Not-So Barren Land There are about 1,700 kinds of plants in the arctic and subarcticadapted to sweeping winds and disturbances of the soilshort and group together to resist the cold temperatures and are protected by the snow during the wintercarry out photosynthesis at low temperatures and low light intensitiesgrowing seasons are short and most plants reproduce by budding and division rather than sexually by flowering
96Tundra: The Not-So Barren Land low shrubs, sedges, reindeer mosses, liverworts, and grasses400 varieties of flowerscrustose and foliose lichen
97Tundra: The Not-So Barren Land AnimalsStrategies evolved to withstand the harsh conditions of the tundra can be divided among those species that are resident and those that are migratory
98Tundra: The Not-So Barren Land Residentsmall number of bird (e.g., ptarmigan) and mammal (e.g., muskox, arctic hare, arctic fox, musk ox)Morphological adaptationslarge, compact bodiesa thick insulating cover of feathers or furpelage and plumage that turns white in winter, brown in summerPhysiological adaptationsability to accumulate thick deposits of fat during the short growing seasoninsulation and as a store of energy for use during the winter, when animal species remain activePopulation adaptationscyclical fluctuations in population size, best seen perhaps in the lemming, a small rodent which is the major herbivore in the tundra's simple food chainpredator populations and plant populations respond in kind to the peaks and crashes of the herbivore populations
99Tundra: The Not-So Barren Land Migratoryspecies such as waterfowl, shorebirds and caribou adapt to the tundra by avoiding the most severe conditions of wintereach year at the end of the short growing season they move southward into the boreal forest or beyond, but return to the tundra to breed due to the long growing season