Chapter 34: The Biosphere: An Introduction to
Earth’s Diverse Environments
1) Ecology – scientific study of the interactions
of organisms with their environment
a) A seafloor ecosystem – hydrothermal vents –
i) 350C near vent,
ii) 2C few meters away
iii)
Where does the energy come from to power
endergonic reactions?
(1) Bacteria (producers) use H2S from vent as high
energy electrons and CO2 from seawater
(a)
chemoautotrophs
2) Ecologist study how organisms interact with
their environment
a) 2-way interaction
i) organisms affected by their environment
ii) environment affected by organisms
(1) bacteria of vent transform energy to usable form
(2) plants – remove CO2 and add O2 to atmosphere
b) Ecology is studied at several levels
i) organism
(1) looking at individuals,
(2) Ex. look at adaptations…
ii) population
(1) Looking at an interbreeding group
(2) ex) follow rate of growth of population, migration
routes, etc…
iii) community
(1) Look at groups of interacting populations
(2) Ex. predation
iv)
Ecosystem
(1) abiotic components
(a) temperature, forms of energy, gases, water, nutrients,
other chemicals
(2) biotic components
(a) organisms
(3) Ex. how do chemicals flow between biotic and abiotic?
(carbon cycle, nitrogen cycle, etc…)
(4) Ex. How does energy flow b/w biotic and abiotic? light
 kinetic  potential  heat
3) The Biosphere
a) biosphere – global ecosystem – sum of all ecosystems on
planet Earth
i) Isolated in space except for light energy coming in and
going out
ii) Patchy
(1) land and water – from a distance
(2) deserts, grasslands, forests, lakes, streams, etc…
(3) Fig 34.2 – mixture of forest, small lakes, open meadow,
river…
(4) Can move even closer and find even more patchiness
(a)each lake has different habitats
(b) habit – environmental area in which an organisms
lives
4) Physical and Chemical Factors Influence Life
in the biosphere
a) Most important abiotic factors
i)
Solar energy
(1) powers all surface terrestrial and shallow water
ecosystems
(2) Limiting in water
(a)most photosynthesis takes place near water surface
(organisms and water absorbs light)
(3) Not very limiting on land
(a)However, competition on forest floors
ii)
Water
(1) aquatic organisms have seemingly unlimited supply
(a)problem: water balance due to different solute
concentrations within and around organisms
(2) Land: main problem is threat of drying out
(a)water tight coverings
(b) kidneys to reabsorb water and concentrate urine
iii) Temperature
(1) Too low and metabolic reactions slow to a crawl
(2) Too high and enzymes denature
(3) mammals and birds are warm blooded
iv) Wind
(1) wind damage can generate openings in forests
(patchiness)
(2) increases rate of evaporation
(a)fine on a hot summer day, dangerous in winter
v)
These factors combine with others to produce physical
and chemical components of environment
(1) Ex. soil – inorganic and organic molecules, water and
air
(a)variables – soil structure, nutrient content, pH
vi) Other abiotics
(1) fires, hurricanes, tornados, volcanic eruptions
5) Organisms are adapted to abiotic and biotic
factors by natural selection
a) species may arrive at a location in two ways
i)
evolves there
(1) pronghorn antelope
(2) evolved on open plains and shrub deserts of North
America over 1 million years ago
ii) disperses there
(1) humans in New York
iii) Examining the pronghorns adaptations to abiotic
factors
(1) abiotic factors in habitat
(a)arid, windswept, extreme temperature fluctuations
both daily and seasonally
(2) adaptiations to abiotic factors
(a)Temperature?
(b) thick coat of hollow hair (traps air, keeps it warm
and uses it for unsulation like a wetsuit does with
water)
(c)can raise patches of hair in hot weather to release heat
(d) Water?
(e)gets moisture (water) from vegetation it eats
(3) adaptations to biotic factors
(a) Food (energy; raw materials)?: small broadleaf
plants (forbs), grasses, woody shrubs
(i) its teeth are shaped to bite and chew these
(ii) stomach has cellulose digesting bacteria (like a
cow)
(b) Predation by wolves, coyotes, and cougars
(i) great speed and endurance
1. sprints 60 mph on flat ground (one of the
fastest mammals)
2. adults can maintain 22mph for 30 minutes
3. tan and white coat – camouflage in open plains
4. keen eyes
5. live in herds
iv) Human hunting seriously reduced numbers
(1) today found in western states
(2) competes with cattle and sheep for food
(3) hunted by humans and coyotes
v)
Could the pronghorn do as well if the open plains
were to become forests over time?
(1) evolutionary adaptations limit geographic distribution
b) Terrestrial
i)
Biomes
9 major types (Fig. 34.9)
(1) many named for climate features
(2) also characterized by organisms adapted to area
(a)ex. grassland more likely to be populated by grazing
animals than a forest
ii) What does distribution of biomes largely depend on ?
(1) climate
(a)temperature
(b) rainfall
(i) if climate in 2 areas is similar, same type of biome
may occur (Fig. 34.9 –deserts, etc…)
1. Sahara desert
2. Gobi desert
a. convergent evolution may occur – different
unrelated species adapted to similar environ.
iii) Biomes grade into each other, variation within biomes
(1) northern coniferous forest – snowfall breaks
branches/small trees – creates opening for deciduous
trees (aspen and birch) (storm, fire, etc… can do this)
(2) FIRE can be important
(a) some grasslands would be replaced by forest
(b) most grasses survive fires (growing point from roots
below surface)
(c)some species of conifers make cones that release
seeds during fire (extreme heat)
iv) Today, natural biomes are being broken up and altered
by humans
(1) leads to high rate of species loss
c) TROPICAL FORESTS (DRY FORESTS – Madagascar
DISC4 38:37)
(1) location: cluster near equator
(2) temperature: almost always warm (constant)
(3) photoperiod: 11-12 hour days year long (constant)
(4) rainfall: variable – determines vegetation that grows
ii) Tropical dry forests – long dry seasons (several months) –
may get several 100cm of rain a day during wet season
(1) Lowland areas (central West Africa, India, Southeast Asia)
(2) scarce rainfall
(3) Plants
(a)thorny
shrubs and trees
(b) succulents
(c)deciduous trees
(i) drop leaves during dry periods prevent water loss
iii) Tropical rain forests (Disc 1 – Pole to pole – New
Guinea)
(1) location: humid equatorial regions
(a)Indonesia, Amazon river basin in South Americas
(2) rainfall: greater than 250 cm per year
(3) among most complex of biomes (many species)
(4) Plants
(a)300 species of trees in only 2.5 acres (50-60m tall)
(b) many layers:
(i) upper canopy
(ii) low-tree layer
(iii)shrub understory
(iv) ground layer
(v) forest floor
(vi) root layer
(c)often a closed canopy
(i) little light reaches floor (competition for light)
(5) Animals
(a)tree
dwellers: monkeys, birds, insects, snakes, bats,
frogs
(6) Poor soil typically
(a) high temps and rainfall = rapid decomposition and
recycling (little buildup of organic material) –
competition for nutrients
(b) almost all nutrients are in organisms at any given
time
(7) Human impact
(a)clear for lumber
(b) burn, farm (doesn’t last long – poor soil), abandon in
a few years
(c)mining
(d) rainforests recover slow, poor soil
d) Savannas (Disc 3 5:15 – red-billed quelea)
i)
dominated by grasses and scattered trees
ii) location: tropics in central south America, central and
south Africa, parts of Australia
(1) North America where temperate forests meets
grasslands of West
iii) Inhibition of tree invasion and maintain small-growth
grasses
(1) frequent fires (lightning, humans)
(2) grazing animals
iv) rapid grass growth support many animals
(1) large grazing mammals – migrate to green pastures and
scattered watering holes
(2) insects (ants and termites) – dominant herbivores
(3) burrow animals common – mice, moles, gophers,
snakes, ground squirrels, worms, numerous arthropods
(4) many of worlds largest herbivores and their predators
inhabit savannas
(a)African Savannahs
giraffes, zebras, antelope (many species),
baboons, lions, cheetahs
(b) Australian Savannahs
(i) kangaroos
(c)North American Savannahs
(i) bison, deer, black bear, coyotes, wolves (mostly
replaced by farms).
(i)
(Disc 2 Australia – 1:07:23 and
Sonoran desert 1:20)
e) Deserts
i)
Driest of all terrestrial biomes
ii) low and unpredictable rainfall (<30cm per year)
iii) temperature
(1) some are hot (daytime soil surface temps > 140F) and
large daily temp. fluctuations (Sahara)
(2) some are cold (Antarctica, deserts west of Rockies)
iv) driest deserts
(1) Central Australia and Sahara in central Africa (<2cm or
rain / year)
(a)evaporation greatly exceeds precipitation
(2) Namib desert
(a)location: Southwest coast of Africa
(b) moist air (fog), but little rainfall and extremely dry
v)
Tend to be centered around 30degrees north and 30
degrees south latitude
(1) southern hemisphere
(a)Kalahari in Africa
(b) central Australia
(2) northern hemisphere
(a)Sahara
(b) Arabian Desert
(c)Mexico (large parts)
(d) Southwestern United States
vi) Rainshadow deserts
(1) deserts of central Asia east of Caucasus mountains
(continuation of Himalayas)
(2) southern argentina east of andes
(3) California and Nevada east of the Sierra Nevada
vii) Life in the deserts
(1) growth and reproduction linked to rainfall
(2) Plants
(a)driest deserts have no vegetation
(b) less dry – scattered deep-rooted shrubs, cacti (Fig.
34.13)
1. saguaro cactus – pleated structure
2. pleats enable cactus to expand upon water
absorption.
(c)plants tend to produce many seeds that lay dormant
until heavy rain triggers germination
(3) Animals
(a)many live in burrows, active only at cool nights
(b) adapted to conserve water
(c)seed eaters common
(i) ants, birds, rodents
(d) who eats the seed eaters?
(i) lizards, snakes, hawks
viii) desertification
(1) process of semi-arid regions becoming deserts
(a)can be caused by humans, overgrazing
f)
Chaparral
i)
Spanish for “place of evergreen scrub oaks”
ii) created when cool seawater meets land with high
average temperatures
iii) plants
(1) region of dense, spiny shrubs with tough, evergreen
leaves – hold moisture (poison oak, scrub oak, cacti,
Yucca whipple etc…)
(2) annual plants also common
(3) adapted to fires (lightning caused)
(a)fire resistant roots
(b) stored food reserves
(c)many seeds produced will ONLY germinate after fire
(d) other are asexual (don’t depend on seeds)
(4) Animals
(a)browsers like deer, fruit-eating birds, seed-eating
rodents,
(b) lizards and snakes
iv) location: mid-latitude coastal areas (Mediterranean
region, coast of Chili, SW Africa, SW Australia,
California.
v)
results from cool ocean currents offshore
(1) leads to mild, rainy winters
(2) long, hot, dry summers
g) Temperate
grasslands (Disc 3 – Steppe)
i)
like tropical savannahs without the trees (except by
rivers and streams)
ii) found in regions with cold winter temps.
(1) pampas in Argentina and Uruguay
(2) steppes in Asia
(3) prairies in Central North America
iii) persistence relies on (inhibit woody plants without
harming below ground grass shoots)
(1) seasonal drought
(2) fires
(3) grazing by large mammals
iv) Animals
(1) bison, pronghorns of North America
(2) gazelle and zebra of African veldt (???)
(3) wild horses and sheep of steepes
v)
animals (rich soil from glacial deposits and decaying
organic matter)
(1) many microorganisms and animals
(a)annelids
(b) arthropods
(c)burrowing mammals (ex. prairie dogs)
vi) amount of rainfall influences height of grasslands
vii) Little left of North American prairies – farmed – one
of most productive agriculture regions in world.
h) Temperate
deciduous forests (Disc 1 pole to
pole) – 15:00
i)
location: throughout midlatitude regions
(1) sufficient moisture to support large trees
(2) Eastern US
(3) most of central Europe
(4) parts of Eastern Asia
(5) parts of Australia
ii) Plants
(1) broadleaf deciduous trees
(a)oak species
(b) hickory
(c)birch
(d) beech
(e)maple
(2) tree types depend on local climate and soil conditions
iii) temperatures
(1) -30C to +30C
iv) precipitation
(1) high and throughout year
v)
growing season of 5-6 months
vi) annual rhythm
(1) trees drop leaves in late autumn
(2) new leaves made in spring
vii) why do they lose leaves
(1) to prevent evaporation of water in low water condition
caused by freezing
viii) compare to tropical rain forests
(1) more open
(2) richer soil – organic and inorganic
(3) lower decomposition rates
(4) thick layer of leaf litter
ix) Animals
(1) invertebrates in soil and litter
(2) vertebrates – mice, shrews, ground squirrels
(3) birds
(4) bobcats, foxes, black bears, mountain lions, etc…
x)
Almost all original forest in North America destroyed
by logging and clearing for agriculture and urban
development
xi) forests recover quick (moist) and have repopulated
much of former range.
i)
Coniferous forests (Disc 1 pole to pole)
i)
cone-bearing evergreen trees (few species)
(1) spruce, pine, fir, hemlock
ii) taiga – boreal or northern coniferous forest
(1) largest terrestrial biome on planet
(2) broad band across North America and Eurasia
(3) reaches southern boarder of arctic tundra
(4) also found at cool, high elevations in temperate
latitudes (mountains)
iii) temperature and precipitation
(1) long cold winters, wet summers sometimes warm
(2) usually snow, insulates ground during winter and
prevents it from freezing too deep so that it can thaw
over summers (also makes opening – breaks branches,
falls trees)
(a)clusters of deciduous trees (birch, willow, aspen,
alder) can grow in openings
iv) soil
(1) nutrient-poor, thin, acidic
(2) needles decompose slowly at low temps
(a)waxy cuticle
v)
fire during drought periods
(1) cones are fire resistant and adapted to release seeds
during fire
vi) Animals
(1) little animal life
(a)needles inedible to most animals
(2) moose, elk, snowshoe hares, squirrels, grizzly bears,
wolves, grouse, migratory birds.
vii) being logged at an alarming rate!
j)
Tundra (Disc 1 – pole to pole)
i)
location (acrtic tundra)
(1) northern most limits of plant growth just before
permanent ice and snow cover and south to coniferous
forests
(2) encircles north pole
(3) alpine tundras - found at high latitudes (even in tropics)
ii) climate
(1) cold, little light for long periods of time
(2) brief warm summers, almost constant daylight
iii) Plants
(1) dwarf woody shrubs, grasses, mosses, and lichen
(fungus/algae or cyanobacteria symbionts)
(2) grow quick and flower rapidly in short summers
iv) permafrost – continuously frozen subsoil
(1) characterizes tundra
(2) underlies 80% Alaska, half of Canada, Scandinavia,
and Russia
(3) depth ranges from few meters to 1500m (5000ft) in
Siberia
(4) only upper part of soil thaws in summer from few
centimeters to several meters.
(5) prevents plant roots from penetrating deep
v)
absence of trees
(1) extremely cold winters, permafrost, high winds
vi) saturated soil
(1) may get little rain, but permafrost prevents drainage and
cold temps limit evaporation
vii) Animals
(1) adaptations
(a)good insulation
(2) large: musk oxen, caribou
(3) small: lemmings (small rodent)
(4) predators: arctic fox. snowy owl
(5) birds – migratory – summer breeding ground
(6) mosquitoes fill air and other insects during summer
6) Polar and high mountain ice (Disc 1 – pole to
pole)
7) Aquatic Biomes (salt water)
a) life began in sea
b) moved to land 3 billions years later
c) Oceans
i)
75% of surface covered by ocean
ii) provide water for almost all rainfall
iii) ocean temps have major effect on climate and wind
iv) marine algae supply substantial portion of
atmospheric oxygen for biosphere
v)
estuary
(1) where freshwater streams and rivers merge with ocean
(a)Long Island Sound
(b) salt content ranges from freshwater (1%) to salt
water (3%)
(c)among most productive biomes on Earth
(i) water enriched with nutrients from river
(ii) oysters, crabs, and many fish present
(iii)many waterfowl feed here
(d) often bordered by mudflats and salt marshes = types
of wetlands
(2) Wetlands
(a)intermediate biomes between aquatic and terrestrial
(b) mudflats, salt marshes, rocky and sandy beaches
(c)usually has saturated soil partly or permanently
(d) intertidal zone –
(i) wetland at edge of estuary or ocean
(ii) flooded by high tides and dry at low tide (about
every 12 hours)
(e)Life forms
(i) Rocky
1. sedentary organisms
a. algae, barnacles, mussles, sea stars, sea
anemones (attach to rocks so not washed
away)
(ii) sandy beachs/ mudflats
1. suspension-feeding worms, clams, predatory
crustaceans (all bury themselves)
2. surface crabs and shorebirds feed along shore
(iii)tide pool – small body of water that remains in a
rock or sand depression during low tide
(3) Other oceanic zones
(a)abiotic factors determine what thrives in these zones
(b) pelagic zone – open ocean itself
highly motile communities (fish, squid, marine
mammals – whales, dolphins)
(ii) phytoplankton – many, many species of
photosynthetic algae and cyanobacterio drift
passively
(iii)zooplankton – animals that drift here, adaptations
to keep afloat.
(iv) fish and other animals eat zooplankton, which eat
phytoplankton
(c)benthic zone – seafloor
(i) depth and light condition determine life forms
(ii) animals
1. attached algae, fungi, bacteria, sponges,
burrowing worms, sea anemones, clams, crabs
fishes
(d) Photic zone
(i) illuminated regions of benthic and pelagic zones
(ii) small portion where photosynthesis can occur
(e)aphotic zone – dark region below photic zone
(i) most extensive part of biosphere
(ii) no photosynthesis
(iii)invertebrates like sea urchins and polychaete
worms, some fish that scavenge sinking organic
matter from above (marine snow, etc…)
(iv) some fish have large eyes to see in dim light,
others use bioluminescence to attract mates and
prey
(v) hydrothermal vent communities
(f) Continental shelves
(i) submerged parts of continents
(g) coral reefs (biome)
(i) found in warm tropical waters above continental
shelf
(i)
(ii) reef
built up year after year by coral animals
(group of cnidarians) – secrete hard exoskeleton
and multicellular algae
(iii)highly fragile – pollution, introduced predators,
souvenir hunters, pet stores, etc…
d) the ocean is not a limitless resource
i)
overharvested
ii) dumping waste
iii) whales near extinction
iv) less seafood
v)
seafood contaminated with toxins
8) Aquatic Biomes (Fresh Water)
a) Lakes, ponds, rivers, streams, wetlands
b) light has great influence
c) Lakes and Ponds
i)
photic and aphotic zone
(1) phytoplankton in photic zone
(2) root plants inhabit shallow waters
ii) benthic zones
(1) microorganisms in benthic community decompose dead
organisms that sink to bottom
(2) cell resp by microorganisms removes oxygen
(a)some lakes only anaerobic microbes can live there
iii) Temperature
(1) during summer upper layer of lake is warm and does
mix with cooler layer below
(2) fish hang in cooler parts of lake unless oxygen is used
up by decomposers
iv) limiting nutrients
(1) nitrogen and phosphorus – limit phytoplankton growth
(2) if temp differences in lake, nutrients released by
decomposers can be trapped in colder, dark waters
(3) in winter, surface water gets colder than lower water,
sinks, nutrients return to surface and O2 brought to
bottom
(4) Today, N and P enter from sewage and runoff (lawns,
agriculture) – produce blooms of algae, reduces light
penetration and when they die and decompose, serious
oxygen depletion can occur.
d) Rivers and streams
i)
communities quite different from lakes and ponds
ii) river changes from source (spring or snow melt) to
where it empties in sea
(1) source
(a)usually cold, clear, low in nutrients
(b) narrow channel, swift currents = little silt on bottom
and no phytoplankton
(c)algae or organic material carried into streams (leaves)
supports most organisms (attached to rocks)
(d) most abundant benthic org. = arthropods – small
crustaceans and insect larvae that eat algae, leaves,
or each other
(e)trout – predominant fish
(i) use sight to find food (clear water)
(2) downstream
(a)river widens and slows
(b) warmer and usually murkier water – sediments and
phytoplankton suspended
(c)worms and insects buried in mud
(d) waterfowl, frogs, catfish and other fish
(i) find food by scent and taste (don’t rely much on
sight)
e) freshwater wetlands
i)
swamps to marshes and bogs
(1) form in shallow basins or along the banks of rivers or
lakes
(2) very rich in species diversity
(3) provide water storage areas (reduce flooding)
(4) improve water quality by filtering pollutants
(a)economic
and ecologically valuable