Chapter 3 Communities, Biomes and Ecosystems

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Chapter 3 Communities, Biomes and Ecosystems
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1. Life in a community
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• Every ecosystem has a tendency to change from
  simple to complex. A final , stable community
  will become established ( climax community)
• What grows and survives varies

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Limiting Factors

• Factors that affect an organisms ability to
  survive in its environment.
• (any condition that keeps the size of a
  population from increasing)
• May be abiotic or biotic
• Fig. 3.1 trees at timberline

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Tolerance

• All organisms have a range of tolerance for
  different conditions.

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Tolerance

• Ability to withstand fluctuations in A or B
  Factors.

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Ecological Succession

• 2 kinds
• Primary
• Secondary

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Ecological Succession

• Change in the composition of species that make up
  a community over time.
• Orderly
• Natural
• Occurs in stages
• Can take decades or centuries

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2. Types of Ecological Succession

• 1. Primary succession
• The collinization of barren land.

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Primary Succession

• First lifeOn barren rock or ice.
• Such as newly formed volcanic island. sand
  dune
• First org. to establish
• Pioneer Species
• Often are Lichens
• (bacteria fungus, OR algae fungus)

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Lichens
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Pioneer Species

• First plants on Barren rocks.
• Lichens, small plants with brief life cycles
• Improve conditions.

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Primary Succession continued

• Soil develops gradually
• grasses overtake the lichens then ferns then
  shrubs and trees.
• Eventually the land
• is colonized by plants that become the main
  vegetation.
• ..The Climax Community

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Succession
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2. Secondary Succession

• Occurs after
• existing community cleared by a disturbance.
• Occurs where
• the soil is intact
• For example following a fire

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Secondary
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Eventually

• A stable community is established.a Climax
  Community
• Influenced by 2 factors
• Temperature
• And
• Rainfall

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Climax Community

• Stable array of species that persists relatively
  unchanged over time.

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Stages of Secondary Succession
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Forests
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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

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Fig. 44.6, p. 760
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Biomes

• Terrestrial
• Aquatic
• Marine
• Estuary
• Freshwater

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3.2 Terrestrial Biomes

• Climate results from uneven heating
• The average weather conditions in an area
• Latitude
• More direct sunlight at equator
• Elevation
• Ocean currents
• Land masses

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Major Terrestrial Biomes

• Characterized by Latitude and Climate
• Tundra
• Boreal Forest (Tiaga) (pine trees)
• Temperate Forest ( deciduous trees)
• Temperate woodland and shrubland ( example
  chaparrel)
• Temperate Grassland
• Desert
• Tropical Savanna
• Tropical Dry ( Seasonal) Forest
• Tropical Rain Forest

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Tundra

• The tundra is cold year-roundit has short cool
  summers and long, severe winters.  Drainage is
  poor
• permafrost
• little precipitation, about 4 to 10 inches per
  year, and what it does receive is usually in the
  form of snow or ice.    There is little diversity
  of species.  Plant life is dominated by mosses,
  grasses, and sedges

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Tundra

• Below polar ice caps
• Treeless
• Permafrost
• Shallow-rooted vegetation
• Plants are low, cushiony mats
• lichens
• Cold and dark most of the year

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A,b arctic c is alpine
Fig. 44.19, p. 771
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Boreal Forest (Taiga)

• Below Tundra
• Pine trees
• Short, moist summers
• Moose, deer

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The Taiga

• Also know as boreal forests, the taiga is
  dominated by conifers (cone-bearing plants), most
  of which are evergreen (bear leaves throughout
  the year).  The taiga has cold winters and warm
  summers. 
• The soil is acidic and mineral-poor.  It is
  covered by a deep layer of partially-decomposed
  conifer needles.

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Temperate Deciduous Forest

• Four distinct seasons
• Hot in the summer to below freezing in the
  winter. 
• Rain is plentiful
• Deciduous trees -drop their leaves in the autumn,
• Broad-leaf deciduous trees
• 4 seasonshot summers, cold winters
• Deer, rabbits, squirrels, oak trees, maple trees

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Tropical Rain Forest

• Warm, uniform temps
• Large amounts of rain throughout the year (
  125-660 cm/yr)
• Vertically layered
• epiphytes

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Tropical rainforest

• Highest species diversity (species rich
• Amazon rainforests produce about
• 40 of the world's oxygen
• One in four pharmaceuticals comes from a plant in
  the tropical rainforests

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Tropical Rainforest

• Plants grow rapidly /use up nutrients.
• This results is a soil that is poor. 
• The tropical rainforest is Dense/not much
  sunlight reaches the forest floor. 
• Adaptations
• Specialized roots help hold up plants in the
  shallow soil
• some plants climb on others to reach the sunlight
  
• smooth bark and smooth or waxy flowers speed the
  run off of water
• plants have shallow roots to help capture
  nutrients from the top level of soil.

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Fig. 44.6, p. 760
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Grassland

• Extremely rich soil
• b/c grasses die off annually
• Well-suited to agriculture
• The Breadbasket of the World
• 2 General Kinds

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Temperate Grassland

• Fertile soil
• Thick cover of grasses
• No trees
• Maintained by periodic fires and animal grazing

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Tropical Savanna

• Grasses and Scattered Trees
• Africa, s. America, Australia
• Hot rainy summers
• Winters- cool dry

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Deserts

• All continents except Europe
• Annual rate of evaporation exceeds rate of
  precipitation
• Less than 26 centimeters annual rainfall
• One third of land surface
• Nocturnal animals
• Plants adapted

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Desert

• Some plant adaptations.
• Some plants, called succulents, store water in
  their stems or leaves
• Long root systems.
• Waxy coating on stems and leaves help reduce
  water loss.
• Flowers that open
• Nocturnal animals

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Aquatic Ecosystems

• Grouped based upon abiotic factors
• Freshwater
• Transitional
• marine

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Freshwater

• Rivers Streams
• Water movement varies
• More plants where water is slow
• Fish feed here

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Lakes ponds

• Bodies of standing freshwater
• Temperature varies with season
• So does oxygen nutrients
• Highest in Autumn and Spring

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Transition Aquatic Ecosystems

• Estuary

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Estuary

• Partially enclosed area where saltwater and
  freshwater mix
• High species diversity
• Important spawning area and nurseries
• Dominated by salt-tolerant plants-algae, seaweed,
  marsh grass
• Lots of waterfowl feed and migrating
• Examples are Chesapeake Bay, San Francisco Bay,
  salt marshes of New England

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Marine Biomes

• Zonation
• Photic Zone
• Aphotic Zone

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Marine Biomes

• Estuaries
• Effects of Tides
• Intertidal Zone
• Animal adaptations here
• In the Light
• In the Dark

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Alpine Tundra

• Occurs at high elevations throughout the world
• No underlying permafrost
• Plants are low, cushions or mats as in arctic
  tundra

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Chapter 4 Population Biology

• How do populations grow?
• What factors inhibit the growth of populations

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4.1 Population DynamicsLearning Objectives

• Population Dynamics
• What is a population?
• Compare patterns of Population growth
• 2 Models
• 1. Exponential Growththe J-curve
• 2. Logistic Growth-The S-Curve
• Describe life-history pattern and compare this to
  graphic representations
• Be able to make predictions as to the effect of
  environmental factors on population growth.

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• How fast do populations grow?

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Population Growth Rate

• How Fast the population is growing
• 2 most important
• Birth Rate Natality
• Death Rate Fatality
• also
• Immigration
• Emigration

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Exponential Growth

• Unchecked growth
• When no limits are put on the growth rate
• J-shaped Curve
• All populations grow at this rate until some
  limiting factor slows the growth rate.

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Exponential Growth

• Fastest rate of growth, under ideal conditions.
• Unchecked Growth
• Initially slow, then speeds up and remains rapid.
• The larger the population becomes, the faster it
  grows!
• J-Curve (if graphed the rate)
• Examples Houseflies, Bacteria

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Exponential Growthunlimited resources
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Exponential growth J-CurveThe larger the
population gets, the faster it grows.

• Aphidsplentiful food, room.

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What limits population growth?

• Limiting Factors
• food, predation, disease, lack of space
• Carrying Capacity
• Maximum of a species an environment supports
  indefinitely.

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Logistic Growth S-shaped curve

• Pop. growth rate slows or stops at the
  populations carrying capacity.
• Occurs when number of births is less than deaths
  OR when emigration exceeds immigration.

carrying capacity
Time
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Copy this picture into your notes, including
labeling.(K is usually used to reference
carrying capacity
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Reproductive Pattern

• Reproductive pattern
• Determines a populations growth.
• 2 generalized patterns
• rate-strategy ( r-strategy)
• K-strategy

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Reproductive Patterns

• R-Strategy Rate Strategists
• This is an adaptation to living in where
  fluctuations in biotic or abiotic factors occurs
• Example mosquitoes
• Changeable or unpredictable environments.
• Populations are controlled by Density-Independent
  factors
• Organisms characteristics
• Small body size
• Short life span
• Mature rapidly
• Reproduce early
• Large numbers of offspring
• Few survive

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K-Strategists

• Live in predictable environments
• So, the carrying capacity of the environment
  changes little from year to year.
• Example elephants and most large mammals, trees
• Organisms characteristics
• Stable environment
• Slow rate of reproduction
• Produce few offspring
• Many survive
• Offspring mature slowly
• Care for their young
• Maintain pop. sizes at or near carrying capacity
• Populations controlled by Density-dependent
  factors

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Population Dispersal Patterns

• The pattern of spacing of individuals within an
  area.
• 3 main patterns of dispersal
• Uniform black bears ( territorial)
  fish-schools (safety good for predation)
• Clumped Most common pattern
• herds of grazing animals, such as American Bison
• Random dandelions

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How organisms are dispersedclumped most common
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Population Density

• The NUMBER of individuals in a given area.

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2 Kinds of Limiting Factors related to dispersal
patterns.

• 1. Density-dependent Factors
• Often biotic factors
• Exert a greater influence the larger the
  population gets.
• EX disease, parasites, competition, predators
• 2. Density Independent Factors
• Affect a population regardless of their density
• Most are abiotic factors
• Ex Volcano, temperature, storms

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• ..\Bio 1\World Population.htm

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1999
1975
domestication of plants, animals 9000 B.C.
(about 11,000 years ago)
agriculturally based urban societies
beginning of industrial, scientific revolutions
Fig. 40.9, p. 695
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Chapter 5 Biodiversity and Conservation
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• Biodiversity
• Genetic diversity
• Species diversity
• Ecosystem diversity

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Dead as a Dodo

• Flightless bird that lived on the island of
  Mauritius
• Killed off by Europeans
• Once the dodo was extinct, a tree native to
  Mauritius stopped reproducing

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Biodiversity Extinction

• 90 percent of all species that have ever lived
  are now extinct
• Biodiversity is greater than ever
• Current range of biodiversity is the result of
  past extinctions and recoveries

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Importance of Biodiversity
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5.2 Threats to Biodiversity

• Extinction Rates
• Background Extinction
• Mass Extinctions

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Humans and Mammalian Diversity

• Humans began hunting mammals about 2 million
  years ago
• About 11,000 years ago, they began to drastically
  reduce mammalian habitats
• Of the 4,500 living mammal species, 300 (6.7
  percent) are endangered

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• Extinction
• Endangered Species
• Threatened
• Introduced Species

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Endangered Species

• An endemic species that is extremely vulnerable
  to extinction
• Endemic means a species originated in one
  geographic region and is found nowhere else

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Threatened Regions
Critically endangered species
Threatened species
Relatively stable species populations intact
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Indicator Species

• Species that provide warning of changes in
  habitat and impending widespread loss of
  biodiversity
• Example
• Migratory birds that breed in N. America and
  winter over in tropical forests
• Study found populations are plummeting as a
  result of deforestation, habitat fragmentation

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Factors that Threaten Biodiversity

• Habitat LossNumber one
• Tropical Rain Forest
• Coral Reefs
• Overexploitation
• Habitat Fragmentation
• Pollution
• Biological Magnification
• Acis Precipitation
• Eutrophication (cultural)

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DDT in Food Webs

• Synthetic pesticide banned in the United States
  since 1970s.
• Top carnivore birds accumulated DDT in their
  tissues.

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Shells are soft, crack, babies die.
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DDT banned in US in 1972!
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Habitat Loss Threats to Coral Reefs

• Natural threats, such as hurricanes
• Man-made threats
• Water pollution, oil spills
• Dredging
• Dynamite and cyanide fishing
• Coral bleaching

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Habitat Loss

• In the U.S.
• 98 percent of tallgrass prairies are gone
• 50 percent of wetlands have been destroyed

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Coral Bleaching

• Reef-building corals have photosynthetic,
  dinoflagellate symbionts
• When stressed, corals expel the protistans
• If the stress persists, the coral will die,
  leaving only its bleached hard parts behind
• Coral bleaching may be an effect of global
  warming and increased sea temperatures

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Habitat Fragmentation

• Habitats are chopped up into patches
• Three effects
• Increases habitat edges
• Decreases number of individuals that can be
  supported may be too few to allow breeding
• Decreases the area in which individuals can find
  food or other resources

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Habitat Degradation
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Introduced Species

• Species that have been introduced into a habitat
• either deliberately or accidentally
• No natural enemies or controls
• Can outcompete native species
• Play a role in 70 percent of cases where endemic
  species are threatened

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Nile Perch in East Africa

• Nile perch were introduced into Lake Victoria as
  a food source
• This predator ate native cichlids drove many
  species to extinction
• Now Nile perch species is close to crashing

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Rabbits in Australia

• Rabbits were introduced for food and hunting
• Without predators, their numbers soared
• Attempts at control using fences or viruses have
  thus far been unsuccessful

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Kudzu in Georgia

• Imported for erosion control
• No natural herbivores, pathogens, or competitors
• Grows over landscapes and cannot be dug up or
  burned out
• May turn out to have some commercial use

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5.3 Conservating Biology
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Rachel Carson

• Oceanographer and marine biologist
• Published Silent Spring in 1962
• Described the harmful effects of pesticides on
  songbirds and other species
• Book helped launch the environmental movement

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Conservation Biology

• Systematic study of biodiversity
• Works to elucidate the evolutionary and
  ecological origins of biodiversity
• Attempts to identify ways to maintain
  biodiversity for the good of human populations

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Density-Dependent Controls

• Logistic growth equation deals with
  density-dependent controls
• Limiting factors become more intense as
  population size increases
• Disease, competition, parasites, toxic
  effects of waste products

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Density-Independent Controls

• Factors that affect population growth regardless
  of population density.
• Natural disasters or climate changes affect large
  and small populations alike

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Age Structure Diagrams

• Show age distribution of a population

SLOW GROWTH
ZERO GROWTH
NEGATIVE GROWTH
RAPID GROWTH
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Pollutants

• Substances with which an ecosystem has had no
  prior evolutionary experience.
• No adaptive mechanisms are in place to deal with
  them

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Air Pollutants

• Carbon oxides
• Sulfur oxides
• Nitrogen oxides
• Volatile organic compounds
• Photochemical oxidants
• Suspended particles

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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

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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

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Thermal Inversion

• Weather pattern in which a layer of cool, dense
  air is trapped beneath a layer of warm air

cool air
warm inversion air
cool air
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Acid Deposition

• Caused by the release of sulfur and nitrogen
  oxides
• Coal-burning power plants and motor vehicles are
  major sources

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Ozone Thinning

• In early spring and summer ozone layer over
  Antarctica thins
• Seasonal loss of ozone is at highest level ever
  recorded

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Effect of Ozone Thinning

• Increased amount of UV radiation reaches Earths
  surface
• UV damages DNA and negatively affects human
  health
• UV also affects plants, lowers primary
  productivity

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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

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Generating Garbage

• Developed countries generate huge amounts of
  waste
• Paper products account for half the total volume
• Recycling can reduce pollutants, save energy,
  ease pressure on landfills

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Land Use

• Almost 21 percent of Earths land is used for
  agriculture or grazing
• About half the Earths land is unsuitable for
  such uses
• Remainder could be used, but at a high ecological
  cost

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Green Revolutions

• Improvements in crop production
• Introduction of mechanized agriculture and
  practices requires inputs of pesticides,
  fertilizer, fossil fuel
• Improving genetic character of crop plants can
  also improve yields

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Deforestation

• Removal of all trees from large tracts of land
• 38 million acres logged each year
• Wood is used for fuel, lumber
• Land is cleared for grazing or crops

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Effects of Deforestation

• Increased leaching and soil erosion
• Increased flooding and sedimentation of
  downstream rivers
• Regional precipitation declines
• Possible amplification of the greenhouse effect

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Regions of Deforestation

• Rates of forest loss are greatest in Brazil,
  Indonesia, Mexico, and Columbia
• Highly mechanized logging is proceeding in
  temperate forests of the United States and Canada

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Reversing Deforestation

• Coalition of groups dedicated to saving Brazils
  remaining forests
• Smokeless wood stoves have saved firewood in
  India
• Kenyan women have planted millions of trees

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Destroying Biodiversity

• Tropical rainforests have the greatest variety of
  insects, most bird species
• Some tropical forest species may prove valuable
  to humans
• Our primate ancestors evolved in forests like the
  ones we are destroying

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Desertification

• Conversion of large tracts of grassland to
  desertlike conditions
• Conversions of cropland that result in more than
  10 percent decline in productivity

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The Dust Bowl

• Occurred in the 1930s in the Great Plains
• Overgrazing and prolonged drought left the ground
  bare
• 1934 winds produced dust storms that stripped
  about 9 million acres of topsoil

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Ongoing Desertification

• Sahel region of Africa is undergoing rapid
  desertification
• Causes are overgrazing, overfarming, and
  prolonged drought
• One solution may be to substitute native
  herbivores for imported cattle

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Water Use and Scarcity

• Most of Earths water is too salty for human
  consumption
• Desalinization is expensive and requires large
  energy inputs
• Irrigation of crops is the main use of freshwater

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Negative Effects of Irrigation

• Salinization, mineral buildup in soil
• Elevation of the water table and waterlogging
• Depletion of aquifers

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Ogallala Aquifer

• Extends from southern South Dakota to central
  Texas
• Major source of water for drinking and irrigation
  
• Overdrafts have depleted half the water from this
  nonrenewable source

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Water Pollutants

• Sewage
• Animal wastes
• Fertilizers
• Pesticides
• Industrial chemicals
• Radioactive material
• Excess heat (thermal pollution)