Transcript Powerpoint lecture here

The Biosphere
Chapter 42
Climate
 Average weather condition in a region
 Affected by:
 amount of incoming solar radiation
 prevailing winds
 elevation
The Atmosphere
 Three layers
 Outer mesosphere
 Middle stratosphere (includes ozone layer)
 Inner troposphere (where air is warmed by
the greenhouse effect)
Warming the Atmosphere
 Solar energy warms the atmosphere and sets
global air circulation patterns in motion
Rotation and Wind Direction
 Earth rotates faster
under the air at the
equator than it does
at the poles
 Deflection east and
west
Seasonal Variation
 Northern end of Earth’s axis tilts toward sun
in June and away in December
 Difference in tilt causes differences in
sunlight intensity and day length
 The greater the distance from the equator,
the more pronounced the seasonal changes
Varying Temperatures
cold
cool temperature
warm temperature
tropical
(equator)
tropical
warm temperature
cool temperature
cold
March
231/2º
June
December
September
Pollutants
 Substances with which an ecosystem
has had no prior evolutionary
experience
 No adaptive mechanisms are in place
to deal with them
Ozone Thinning
 In early spring and summer ozone
layer over Antarctica thins
 Seasonal loss of ozone is at highest
level ever recorded
Effect of Ozone Thinning
 Increased amount of UV radiation
reaches Earth’s surface
 UV damages DNA and negatively
affects human health
 UV also affects plants, lowers primary
productivity
Air Pollutants
 Carbon oxides
 Sulfur oxides
 Nitrogen oxides
 Volatile organic compounds
 Photochemical oxidants
 Suspended particles
Protecting the Ozone Layer
 CFC production has been halted in
developed countries, will be phased out in
developing countries
 Methyl bromide will be phased out
 Even with bans it will take more than 50
years for ozone levels to recover
Thermal Inversion
 Weather pattern in which a layer of cool,
dense air is trapped beneath a layer of warm
air
cooler air
normal circulation
cool air
warm air
cool air
warm inversion air
cool air
Industrial Smog
 Gray-air smog
 Forms over cities that burn large amounts of
coal and heavy fuel oils; mainly in
developing countries
 Main components are sulfur oxides and
suspended particles
Photochemical Smog
 Brown-air smog
 Forms when sunlight interacts with
components from automobile exhaust
 Nitrogen oxides are the main culprits
 Hot days contribute to formation
Acid Deposition
 Caused by the release of
sulfur and nitrogen
oxides
 Coal-burning power
plants and motor vehicles
are major sources
Suspended Particulate Matter
Ocean Currents
 Upper waters move in currents that distribute nutrients
and affect regional climates
Rain Shadow
 Air rises on the windward side, loses moisture
before passing over the mountain
Monsoons
 A pattern of wind circulation that changes
seasonally
 Affect continents north and south of warmwater oceans
 Can cause seasonal variation in rains
Coastal Breezes
 Breeze blows in direction of warmer region
 Direction varies with time of day
Biogeographic Realms
 Six areas in which plants and animals
are somewhat similar
 Maintain their identity because of
climate and physical barriers that tend
to maintain isolation between species
Biomes
 Regions of land characterized by habitat
conditions and community structure
 Distinctive biomes prevail at certain
latitudes and elevations
nearctic
neotropical
palearctic
oriental
ethiopian
australian
Hot Spots
 Portions of biomes that show the greatest
biodiversity
 Conservationists are working to inventory
and protect these regions
 24 hot spots hold more than half of all
terrestrial species
Deserts
 Less than 10 centimeters annual
rainfall, high level of evaporation
 Tend to occur at 30 degrees north and
south and in rain shadows
 One third of land surface is arid or
semiarid
Dry Shrublands
and Woodlands
 Semiarid regions with cooler, wet
winters and hot, dry summers
 Tend to occur in western or southern
coastal regions between latitudes of
30 and 40 degrees
Forest Biomes
Tall trees form a continuous canopy
 Evergreen broadleaves in tropical latitudes
 Deciduous broadleaves in most temperate
latitudes
 Evergreen conifers at high temperate elevations
and at high latitudes
Arctic Tundra
 Occurs at high latitudes between polar
ice cap and boreal forests
 Summers are short and snow-free
 Permafrost lies beneath surface,
causes waterlogging in summer
 Nutrient cycling is very slow
Alpine Tundra
 Occurs at high elevations throughout the world
 No underlying permafrost
 Plants are low, cushions or mats as in arctic
tundra
How much are you aware?
Is the native vegetation of the place where you live forest,
grassland, or dessert?
Can you describe the physical characteristics of three plant
species that are native to your area?
What body of water serves as the source of your tap water?
How is your electricity generated?
Where does your garbage go?
Biomes - Land
 Primary vegetation types
 Four basic land biomes:




Forest
Grassland
Desert
Tundra
Biomes - Land
Forest




Tropical forests - Highly diverse and capture all light
Temperate forests - Deciduous trees which drop leaves annually
Boreal forests - highly uniform, coniferous trees of 1 or 2 species
Chaparrel - woody spiny evergreen shrubs
 Grassland - area where rainfall is not enough for tree growth
 Tropical - savannas - free trees - cleared by fires
 Temperate - prairies (tall grass) and steppes (short grass)
Biomes - Land
Desert
 Rainfall is sparse
 Animals and plants have evolved ways to conserve
water
Tundra
 Coldest biome - close to the poles
 Permafrost - keeps soils moist and bogged
Biomes - Aquatic
 Freshwater
 Lakes and Ponds - surrounded by land
 Vernal ponds - dry up in the summer
 Rivers and Streams - flowing water
 Wetlands - support above water plants
 Saltwater
 Oceans
 Coral reefs
 Estuaries
Soil Characteristics
 Amount of humus
 pH
 Degree of aeration
 Ability to hold or drain water
 Mineral content
Soil Profiles
 Layer structure of
soil
 Soil characteristics
determine what
plants will grow and
how well
Rain forest
Grassland
Desert
Deciduous
Coniferous
Lakes
 Bodies of standing freshwater
 Eutrophic lake is shallow, nutrient-rich, has
high primary productivity
 Oligotrophic lake is deep, nutrient-poor,
has low primary productivity
Lake Zonation
LITTORAL
LITTORAL
LIMNETIC
limit of effective
light penetration
PROFUNDAL
Thermal Layering
 In temperate-zone lakes, water can form
distinct layers during summer
wind
THERMOCLINE
Seasonal Overturn
 In spring and autumn, temperatures in the
lake become more uniform
 Oxygen-rich surface waters mix with deeper
oxygen-poor layers
 Nutrients that accumulated at bottom are
brought to the surface
Eutrophication
 How do nutrients enter a lake?
 Can occur naturally over long time span
 Can be triggered by pollutants
Streams
 Begin as springs or seeps
 Carry nutrients downstream
 Solute concentrations are influenced by
streambed composition and human
activities
Estuary
 Partially enclosed area where
saltwater and freshwater mix
 Dominated by salt-tolerant plants
 Examples are Chesapeake Bay, San
Francisco Bay, salt marshes of New
England
Estuarine Food Webs
 Primary producers are phytoplankton and
salt-tolerant plants
 Much primary production enters detrital
food webs
 Detritus feeds bacteria, nematodes, snails,
crabs, fish
Mangrove Wetlands
 Tropical saltwater ecosystem
 Form in nutrient-rich tidal flats
 Dominant plants are salt-tolerant
mangroves
 Florida, Southeast Asia
Rocky Intertidal
 Grazing food webs prevail
 Vertical zonation is readily apparent
 Diversity is greatest in the lower littoral
zone
Sandy Coastlines
 Vertical zonation is less obvious than along
rocky shores
 Detrital food webs predominate
Intertidal Zones
 Littoral zone is submerged only during
highest tides of the year
 Midlittoral zone is regularly submerged and
exposed
 Lower littoral is exposed only during
lowest tides of the year
Coral Reefs
 Develop in clear, warm waters near coasts
or around volcanic islands, mainly between
latitudes 25° north
and south
 Coral bleaching is
on the rise –
occurs when sea
temperatures rise
Ocean Provinces
 Benthic province - sediments and
rocks at bottom
 Pelagic province - full volume of water
 Neritic zone is near continental shelves
 Oceanic zone is ocean basins
The Open Ocean
neritic
zone
intertidal zone
oceanic
zone
air at
surface
continental
shelf
PELAGIC
PROVINCE
BENTHIC
PROVINCE
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bathyal
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2,000
abyssal
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4,000
hadal
zone
deep-sea
trenches
11,0000
depth (meters)
Phytoplankton
 Floating or weakly swimming
photoautotrophs; form the base for most
oceanic food webs
 Ultraplankton are photosynthetic bacteria
Deep Ocean Food Webs
 Regions too dark for photosynthesis
 Marine snow supports a detrital food web
 Organic matter drifts down from shallower
water
 Diverse species migrate up and down in
water column daily
Hydrothermal Vents
 Openings in ocean floor that spew mineralrich, superheated water
 Primary producers are chemoautotrophic
bacteria; use sulfides as energy source
 Life may have originated in similar
conditions on early Earth
Upwelling
 Upward movement
of water along a
coast; replaces
surface waters that
move away from
shore
ENSO
 El Nino Southern Oscillation
 Climactic event that involves changes
in sea surface temperature and air
circulation patterns in the equatorial
Pacific Ocean
Between ENSOs
 Warm water and heavy rainfall move west
across the Pacific
 Warm moist air rises in the western Pacific
causing storms
 Upwelling of cool water along western
coasts
Between an ENSO
warm, moist, ascending
air masses, low pressure,
storms in western Pacific
t
low wes
b
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high w
to east
t to w
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w
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clear skies, dry
descending air
masses, high
pressure
est
wind
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eq
ater
w
g
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warm
upwelling of cold
water to 30-160
feet below surface
During an ENSO
 Trade winds weaken and warm water flows east
across the Pacific
 Sea surface temperatures rise
 Upwelling along western coasts ceases
 Heavy rainfall occurs along coasts, droughts
elsewhere
During ENSOs
clear skies,
descending air
masses, high
pressure
w west
o
l
b
s
d
n
high wi
warm, moist
ascending air
masses, low
pressure,
storms
rain falls in
central Pacific
aken;
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w
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w
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no upwelling;
cold water as
deep as 500 feet
below surface
Cholera Connection
 Cholera outbreaks are correlated with rises
in sea temperature
 Dormant stage of causative organism lives
in copepods
 Copepod population increases when
phytoplankton increase in warming seas