CHAPTER 6 PART 2

----------------------------------BIOMES----------------------------- 

 

Defined as  climax communities with wide geographic distribution

 

It is a concept and a generalization and there are variations BUT it is a useful term

 

In broad terms the general structure of the ecosystem and the kinds of niches  and habitats present are similar.

Some of the biomes on earth include:

Desert - very dry, either hot or cold Tundra - cool, treeless, and dry. The permanently frozen soil layer is called permafrost. Scrub - coastal area with hot, dry summers and mild, cool, rainy winters Taiga or Coniferous Forest - cool and dry, with coniferous trees Temperate Deciduous Forest - cool and rainy, with deciduous trees Grassland - Windy, partly dry sea of grass with few trees, including tropical savanna, prairie,

steppe, pampas, etc. Mountain Biomes - there are a lot of different mountainous biomes, from grasslands at low

altitudes, taiga (coniferous forests) below the treeline, and alpine (the same as tundra) Temperate Rain Forest - cool and wet Tropical Rain Forest - warm and very wet Wetlands - there are many types of wetlands, including swamps, marshes, moors, bogs, fens,

sloughs, etc. These have nutrient rich soil. Freshwater Marsh - a wetland located near streams, rivers and lakes Marine (ocean or sea)

7 minute biome video

http://www.youtube.com/watch?v=ag5ATGEplbU

we will discuss some terrestrial biomes......

 

The two important non-biological factors are PRECIPITATION AND TEMPERATURE

 

Precipitation:  total amount, form, seasonal distribution

 

Snow, rain, sleet----even spacing or wet and dry season

 

Temperature:  tropical, polar  or even division between hot and cold

 

Other factors:  periodic fires, favor shrubs over woody trees

Strong winds—no big trees and very dry soi

 

Type of soil--  sandy will dry out, wet soil favors certain types of species.

 

Distribution of terrestrial ecosystems is primary related to temperature and precipitation

 

Warm near equator and cool toward poles.  BUT  height above sea level is important because it is related to temperature.

 

Climb a mountain and pass through biomes.  a very handy sampling of biomes

DESERT

primary factor is LACK OF WATER  generally less that  10 inches or 25 cm of water per year

When and how is different for different deserts. either in winter months or wet season OR infrequent thundershowers

Problems with thundershowers is that rain RUNS OFF and does not sink in.

ALSO   rate of EVAPORATION   is high  ---this means that flowering and growth of plants occurs in wet season or time.ALSO  desert is WINDY and this leads to drying

We think of deserts and hot and dry and devoid of life HOWEVER deserts are full of life and can be cool or cold

Sahara and deserts of the southwest of US and Mexico are hot mostly but Gobi desert in Central Asia can be very cold during winter and have cool summers

winter in gobi desert--note snow.

ALSO desert  TEMPERATURE  can very widely in  24 hour period

since low precipitation there is low cloud cover and hence sun is not blocked---very hotat night there are no clouds to insulate heat from leaving and radiational cooling leads to very cool temps at night.

Species of animals---high diversity low numbers or density.

animals and plants have special adaptations to survive desert temps, lack of water and drying

examples--small leaves, or lose leaves in winter or like CACTUS will store water in spongy bodies or rootsseeds will lie dormant and then grow rapidly during rainy season, reproduce and die and then wait for next rain. could be months

perennial plants flower reproduce and during rainy season

spiny plant in desert--will keep animals from eating them

]

Animals of the desert

populations are smallsmall in sizehide during dayno large groupssurvive with little waterouter skin resists water losskidneys very efficient at retaining wateractive in cool parts of daymay be underground for most of hotter part of day

GRASSLAND

also call prairies or steppes   25-75 cm or 10-30 inches of rain per year

widely distributed  over temperature regions

major factor is moisture available

windy with hot summers and cold to mild winters

FIRE is important is some areas to prevent trees from growing AND to provide nutrients

GRASSES are 60-90 % of the vegetation with other flowering plants

grasses have extensive root systems with bind soil

trees are rare, need lots of water   found along watercourses

Primary consumers are animals that eat grass   grazing animals like  bison, wildebeest, sheep, cattle, horses, goats

animals function to convert grass to dung and to prevent invasion of woody plants by eating them

Grass can be grazed and return healthy

more little animals

end  11---27--07

insects, grasshoppers, dung beetles, fliesherbivorous mammals like mice and squirrelsbirds feeding seeds, plants, insectsreptiles snakescarnivores like coyotes foxes hawks which eat small mammals

Most moist grassland has been converted to agriculturedeep rich soil is good for corn (maize) and wheat---these are cultivated grasses

dry grassland has been converted to domesticated grazers like cattle sheep goats

little natural or undisturbed grassland is left and should be preserved for grassland species that once occupied vast areas of globe

SAVANNA

tropical parts of Africa, South America and Australia--extensive grassland spotted with trees.

20 to 60 inches of rain per year   ( 50 to 150 cm) not distributed evenly

drought and then rain---season ecosystem

plants and animals time reproductive activities to rainy period

mostly grass with some drought resistant thorny trees

Fire is important and trees are fire resistant (not fire proof)many trees are legumes and nitrogen fixers and provide shade and nesting sites

animals--mostly grazing animals  wallabies AUS, wildebeests, zebras, elephants, antelope, capybara  SA

Africa--lion, hyena, leopard  eat the grazers

rodents, birds, insects, reptilesmound building termites common

Mediterranean Shrubland  (Chaparral)

located near an ocean and have wet cool winters and hot dry summersrain is 40 to 100 cm or 15-40 inchestypical of Mediterranean and coastal California  (southern)southern tip of Africa and west coast of Chile and southern Australia

plants--woody shrubs that can withstand hot dry summer, plants may be dormant in summer

Fire is common and shrubs are adapted to this

animals vary widely, many types of insects birds reptiles mammalsIn California  rattlesnakes, spiders, coyotes, lizards, and rodents are typical

TROPICAL DRY FOREST

tropical dry forestseasonal rainfall important

a monsoon climate  several months of heavy rain followed by extensive dry period which can range from a few to  8 months

The rainfall can range from  50cm or 20 inches to 200 cm or 80 inches

Plants have adapted to this dry wet cycle,  can endure drought,

Dry periods are a very hard time so some trees will drop their leaves during the dry period

locations:  parts of Central and South America, Australia, Africa and Asia (India and Myranmar)

Tropical Rain Forest

location:  Central South America Africa, Southeast Asia, some islands in Caribbean Sea and Pacific Ocean

temperature:  warm and constant, no frost and it rains every day-

200cm or 80 inches of rain per year  to a maximum of 500cm to 200 inches

plants grow fast due to warm temp and rainfall BUT SOIL USUALLY POOR.

why?---water tends to carry away nutrients that is not immediately taken up by roots

Tree-- extensive root networks associated with fungi  (micorhizza) near surface of soil to allow capture of nutrients before they are carried away.

Most nutrients are tied up in biomass  NOT IN SOIL.  These area make poor farmland

end 12-06-------------------------------------------------------------

Rainfall is a source of nutrients because atmospheric particles and gases dissolve as rain falls.

Epiphytic plants (plants that live on surface of others plants) can trap many of these particle before they reach the soil.

Understory vines grow toward sun on supporting trees--why?  looking for sun, competition for sunlight

ferns, mosses and orchids grow on tree surfaces.

MOST DIVERSE BIOME--mores species here than in rest of world combined

a few square kilometers have hundreds of species of trees (unlike where we live)

Same species of tree can be a kilometer or more apart (very different from where we live)

Balsa teakwood and ornamental woods are found here

Each tree has a community of plants and animals that use it as food shelter and support

THE CANOPY -- a solid wall of leaves between the sun and forest floor.  There can be two or three levels here.

EMERGENT TREES --  a few three will stick up above the canopy

below the canopy are UNDERSTORY TREES

below that  THE FOREST FLOOR

many new organisms live in canopy --new research is showing

Key--most of sunlight is captured by the trees-so only shade tolerant plants

Many types of plants, animals

animals--insects like--ants, termites, moths, butterflies, beetles---birds are common

climbing mammals, tree frogs, lizards---insects are food for many animals

Flowers and fruit and available YEAR ROUND   lots of nectar and fruit feeding birds and mammals

very important in pollination and spreading seeds.

Very low light levels during the day and difficult to see during the day due to leaves and vines and plants so animals communicate often by sounds.

Environmental Pressures

logging and agricultural

these are often poor countries and try to exploit the rainforest for jobs and money

AGRICULTURE IS NOT SUCCESSFUL HERE--cannot take repeated growing seasons of growth

Forestry can be sustainable but in many cases is not, too rapid exploitation

TEMPERATE DECIDUOUS FOREST

look familiar?  this is where we live.

There is a winter summer change here and  have trees that lose there leaves in winter and get them back in spring.

location:  eastern half of US and parts of central and southeastern Canada, southern Africa, and many areas of Europe and Asia

southern africa not shown on this map

rainfall:   75 to 100 cm or 30 to 60 inches per year.winter are relatively mild and plants can grow for about half a year

each area has certain species of tree that are major producers for the biome

unlike tropical rain forest here there are many fewer species and many forests consist of

two or three dominant species.

common species:  maple, birch, aspen , beech, oaks and hickory

tall tree shade the forest floor---here small flower plants grow--these plants have adapted by storing foods in underground structures and in spring before leaves come out on trees the flowers can capture sunlight and reproduce before they are shaded.

also smaller shrubs are found

animals:  many insects which eat leaves and tree wood   -- beetles, moth larvae, wasps and ants are examples

Birds live here but most are MIGRANTS--arrive in spring, reproduce in summer, leave in fall--the food is the large insect population also fruit seeds.

year round residents:  some birds like  woodpeckers, grouse, turkey and some finches

amphibians (frogs, toads, salamanders) reptiles (snakes and lizards) prey on insects and other small animals.

small and large mammals: mice ,squirrels, deer, shrews, moles and oppossums

Predators:  foxes, badgers, weasles, coyotes, and birds of prey

TAIGA   northern coniferous forest, boreal forestRussian for forest

type of plant:  evergreen coniferous forest

location:  southern half of Canada, parts of northern Europe, and much of Russia

climate:  short cool summers, long winters with lots of snow, winters are harsh and can last 6 monthssoils freezes

precipitation:  25 to 100 cm or 10 to 40 inches

very humid due to snow melt in spring and low temperature combine to reduce evaporation

landscape:  bogs, lakes and ponds

common trees:  spruces, firs, and larches  adapted to winter and dry??

dry why?  moisture fall as snow and stays above soil and melts in spring

needle shaped leaves prevent water loss, larch lose needles in fall,  branches flexible to shed snow in fall, tree shaped like a pyramid

sun is low in sky and photosynthesis is lower

animals: temporarily active in summer, most birds are migratory and feed on insect population not around in winter

permanent birds:  woodpecker, owls, grousemammals: deer, caribou, moose, wolvesfew amphibians and reptiles because it is too cold

TUNDRA

North of the Taiga is the Tundra

description

Lacks treespermanently frozen SUBSURFACE soil called PERMAFROST: 

climate :  cold and windy  (up to 10 months of winter)

precipitation:   less than 25cm or 10 inches  like the desert

temperature:  short cool summer, summer temperatures and usually less than  50F or 10C  hence very low evaporation rate

land is waterlogged due to permafrost which does not let water sink into soil  many ponds

and pools (shallow)

animals:  water attracts waterfowl like ducks and geese  (migrate there during spring, raise young in summer migrate south in fall)

Top few inches will thaw and some plants will grow but be short (less that 8 inches or 20 cm)

plants: grasses, dwarf birch, dwarf willow and lichens like reindeer moss

insects:  lots and serve as food for migratory birds

permanent residents: birds like ptarmigan and snowy owl

No reptiles or amphibians can live here

Hardy mammals live here: musk oxen, caribou (reindeer), arctic hare, and lemmings---these survive by eating the vegetation, short grasses and plants

Predators: arctic foxes, wolves, and owls.

Key point--very short growing season--damage to land will take a long time to heal.

ALPINE TUNDRA  -- found on some mountaintops around the world.  General appearance is similar to Tundra although many species of animals and plants are different.  Also many animals will migrate to alpine tundra in summer and return to lower elevations in winter

key point --- tundra due to elevation