Biomes

Section #3:Grassland, Desert, and Tundra Biomes

Biomes of the World

General Info

•found in climates that have less rainfall

•less rainfall = less species diversity

•although you might have less variety, you still might have high numbers of individuals in those species that are present

Savannas

• these grasslands are located in tropical & subtropical areas near the equator

• found in parts of Africa, India, Australia, and South America

• overall receive little precipitation throughout the year – but there are periods of heavy rainfall followed by periods of drought

Vegetation of the Savannas

• contain grasses, scattered trees, and shrubs

• plants must be able to survive prolonged periods without water

• plants have horizontal roots systems to capture as much moisture as possible

• grasses have long vertical leaves that expose less surface area to the hot sun

• some savanna plants even lose their leaves during the dry season to conserve water

• thorns & sharp leaves keep herbivores at bay

African Savanna

Savanna Fires

•during the dry season, fires often sweep across the savanna burning the grasses and shrubs

•this returns nutrients to the soil

•plants quickly regenerate from the shallow root systems

Animals of the Savanna

• mostly grazing herbivores & the predators that feed on them

• some grazers have adopted a migratory way of life to follow the rains & find newly sprouted grasses & fresh watering holes

• predators usually follow & stalk the migratory animals

• savanna animals usually give birth only during the rainy season when more food is available to increase chances of survival

Competition in the Savanna

• herbivore species reduce the competition for food by eating vegetation at different heights

• Example: – small gazelles – feed on grasses– black rhinos – feed on shrubs– giraffes – feed on tree leaves

Temperate Grasslands

• dominated by grasses, very few trees

• hot summers, cold winters• moderate rainfall, 50-88 cm of

precipitation per year• summer temps and lack of

precipitation can make the grasslands susceptible to fires that commonly sweep across the lands

Temperate Grasslands

• located on the interior of continents - include North American prairies, steppes of Russia & the Ukraine, and the pampas of South America

• few natural temperate grasslands remain, most have been replaced by farms & grazing areas

• located near mountains that block the grasslands from receiving much precipitation

Plants of theTemperate Grasslands

• mostly perennials – prairie grasses & wildflowers

• grass height depends on root depth• root systems are dense – designed to

survive the periods of drought & also hold the rich soil in place

• few trees can survive – little rain, fires, & constant wind thwart tree growth

Grasslands

Animals of theTemperate Grasslands

• grazers with large, flat teeth for chewing the coarse prairie grasses (bison & antelope)

• burrowers like badgers & prairie dogs are protected underground from the weather & fires – also they burrow underground to escape predators

Threats of theTemperate Grasslands

• most fertile soil – so many people farm or graze the grasslands

• grain crops do not have good root systems to hold the soil – leads to soil erosion

• overgrazing leads to grasses being overeaten & trampled – soil cannot regenerate & becomes less productive

Similarities? Differences?

The Chaparral

• type of temperate woodland biome• located in mid-latitudes (30° N or S)• near coastal areas with Mediterranean

climates• warm, dry summers & mid, wet winters• too dry to support a forest, but more

rain than a desert• receives enough precipitation to

support vegetation that grows in bunches

Chaparral

The Chaparral Plants

• mostly low-lying evergreen plants that grow in dense patches

• dominated by broad-leafed evergreen shrubs

• plants include chamise, manzanita, scrub oak, olive trees, sage and bay herbs, plus piñon & juniper trees

The Chaparral Plants

• the small, leathery leaves retain water and contain oils that promote burning

• well adapted to survive fires that kill competition for sunlight

• can re-sprout from small bits of plant tissue

The Chaparral Animals

• examples include quail, lizards, chipmunks, mule deer

• most animals utilize camouflage (shape or coloring) to blend into the environment

Threats to the Chaparral

• human development of the land for both commercial & residential use

• humans like the area because of the mild climate year-round, proximity to oceans, and the large amounts of sunlight

Deserts

• areas that receive less than 25cm of precipitation a year

• have little or no vegetation• extreme temperatures• located at several latitudes

covering 1/5 of the Earth’s landmasses

• located near large mtn. ranges that block the passage of moisture-filled clouds

Desert Examples

• hot deserts – Sonora Desert, Arizona– Sahara, Africa– Australia

• cold deserts– Gobi Desert, China– Greenland– Antarctica

Desert Plants • all plants must be adapted to

obtain & conserve water• some plants even die & drop their

seeds when the conditions get too dry

• the seeds remain dormant until the next rainfall when they quickly germinate & grow

• some can even survive when their water content drops to only 30% of their mass

Other Adaptations

• succulents - such as cactuses – have thick fleshy stems & leaves to store water

• waxy coatings to reduce water loss• sharp spines or thorns to keep

thirsty animals away• plant roots that spread out just

under the sand to absorb as much rain as possible

Desert Animals • reptiles – like the Gila monster,

rattlesnakes, & lizards – have thick scaly skin to prevent water loss

• amphibians – like the spadefoot toad – survive the high temps by ESTIVATING (burying themselves in the ground and sleeping through the dry season)

• desert insects & spiders are covered in body armor to retain water

• most creatures are nocturnal to avoid the heat of the day

Tundra

• located north of the Arctic Circle• very short summers• topsoil thaws out during the

summer months creating a pattern of bogs & swamps across the land

• below the topsoil is PERMAFROST – permanently frozen ground

• constant winds

Tundra Vegetation

• dominated by tough grasses, lichens, herbs, & small shrubs that grow close to the ground

• soil is extremely thin – wide, shallow roots anchor plants against the icy winds

• lichens & mosses don’t even need soil to grow

• plants try to absorb heat from the sunlit soil

Tundra Animals

• summer wet areas are breeding grounds for huge numbers of swarming insects like mosquitoes & black flies

• many migratory birds feed on these insects

• some herbivores are temporary summer visitors like caribou, deer, & moose plus the wolves that hunt them

Tundra Animals

• some very well insulated creatures stay year-round, like arctic foxes, arctic hares, ptarmigan, & lemmings

• although they may burrow to escape the cold, they are still active during the winter, often growing white fur to camouflage themselves in the winter snow

Threats to the Tundra

• very fragile biome• simple food chains can be easily

disrupted and lead to the demise of the other species

• land is easily damaged & slow to recover

• until recently, most areas were undisturbed by human activities – until oil was discovered

Threats to the Tundra

•oil exploration, extraction, & transport has been particularly disruptive to plants and animals

•pollution from spills or leaks of oil & other toxic materials can lead to the poisoning of food & water sources

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