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Introduction to Environmental Science. Chapters 1 and 2. We Cannot Create or Destroy Matter. Law of conservation of matter – matter cannot be created nor destroyed Matter is converted from one form to another. Everything we think we have thrown away remains here with us in some form….

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we cannot create or destroy matter
We Cannot Create or Destroy Matter
  • Law of conservation of matter – matter cannot be created nor destroyed
      • Matter is converted from one form to another

Everything we think we have thrown away remains here with us in some form…

energy changes are governed by two scientific laws
Energy Changes Are Governed by Two Scientific Laws
  • First Law of Thermodynamics
    • Energy input always equals energy output
  • Second Law of Thermodynamics
    • Energy always goes from a more useful to a less useful form when it changes from one form to another
      • Decreased energy efficiency
systems respond to change through feedback loops
Systems Respond to Change through Feedback Loops
  • Positive feedback loop - causes a system to change in the same direction
systems respond to change through feedback loops1
Systems Respond to Change through Feedback Loops
  • Negative feedback loop – causes a system to change in the opposite direction from which it is moving
    • Opposing process
  • Can promote sustainability!
    • Aluminum mining  can  recycling
time delays can allow a system to reach a tipping point
Time Delays Can Allow a System to Reach a Tipping Point
  • Time delays vary
    • Between the input of a feedback stimulus and the response to it
    • Example: Planting trees
  • Tipping point, threshold level
    • Causes a shift in the behavior of a system
system effects can be amplified through synergy
System Effects Can Be Amplified through Synergy
  • Synergistic interaction – two or more processes interact so that the combined effect is greater than the sum of their separate effects
    • Helpful
      • E.g., campaign vs. individual persuasion
    • Harmful
      • E.g., Smoking and inhaling asbestos particles


Chapters 3 and 4

habitat vs niche
Habitat vs. Niche
  • Habitat – place where an organism lives
    • Organisms address
  • Niche – role of an organism in an ecosystem (physical, chemical, and biological conditions that a species needs to live and reproduce)
    • Organisms occupation
  • Thousands of organisms can occupy the same habitat but each organism has its own niche.
levels of organization of life
Levels of Organization of Life
  • Organism- a living thing
  • Population- a group of organisms of the same species that live in a particular area
  • Community- populations of different species that live in one particular area
several abiotic factors can limit population growth
Several Abiotic Factors Can Limit Population Growth
  • Limiting factor principle
    • Too much or too little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimal range of tolerance
range of tolerance for a population of organisms
Range of Tolerance for a Population of Organisms
  • Range of tolerance may vary in populations
    • Small differences in genetic makeup, health, and age
ecological efficiency
Ecological Efficiency
  • No organism EVER receives all of the energy from the organism it just ate
  • 10% Law
    • Only 10% of the energy from one trophic level is transferred to the next
some ecosystems produce plant matter faster than others do
Some Ecosystems Produce Plant Matter Faster Than Others Do
  • Gross primary productivity (GPP)
    • Rate at which an ecosystem’s producers convert solar energy into chemical energy stored in their tissues
  • Net primary productivity (NPP)
    • Rate they create and store energy minus the energy they use for homeostasis
    • Ecosystems and life zones differ in their NPP


nutrients cycle in the biosphere
Nutrients Cycle in the Biosphere
  • Biogeochemical cycles, nutrient cycles
    • Nitrogen
    • Hydrologic
    • Carbon
    • Phosphorus
    • Sulfur
  • Connect past, present, and future forms of life
nitrogen fixation
Nitrogen Fixation
  • Nitrogen gas cannot be used by living things directly
    • Converted by lightening
  • Bacteria in soil and ocean convert nitrogen gas into ammonium (NH4+) and nitrates (NO3-)
    • Fixation
  • Used by plants to produce amino acids, proteins, nucleic acids, and vitamins
  • When organism dies bacteria convert proteins into ammonia or ammonium
    • Ammonification
returning nitrogen
Returning Nitrogen
  • Specialized bacteria in soil and bottom of lakes convert NH3 and NH4+ back into nitrates
    • Nitrification
  • Nitrates are converted to nitrogen gas and returned to the atmosphere
    • Denitrification
    • N2
    • N2O
nitrogen cycle summary
Nitrogen Cycle Summary
  • Fixation
    • gas  ammonium or nitrate
  • Assimilation
    • Taken up by plants through roots; incorporated into proteins
  • Ammonification
    • Bacteria break down proteins into ammonia and ammonium
  • Nitrification
    • Ammonia  nitrates
  • Denitrification
    • nitrates  gas
human intervention in the nitrogen cycle
Human intervention in the nitrogen cycle
  • Additional NO and N2O
    • Burning fuels at high temperatures
  • Destruction of forest, grasslands, and wetlands
  • Add excess nitrates to bodies of water
    • Runoff
  • Remove nitrogen from topsoil
    • Harvesting nitrogen rich crops and irrigation
alteration of the hydrologic cycle by humans
Alteration of the hydrologic cycle by humans
  • Withdrawal of large amounts of freshwater at rates faster than nature can replace it
  • Clearing vegetation
    • Increases temperature and thus evaporation
  • Increased flooding when wetlands are drained
carbon cycle equations
Carbon Cycle Equations

Cellular Respiration

C6H12O6  +  6O2  6CO2  +  6H2O +ATP 


6CO2 + 6H2O sunlight C6H12O6 + 6O2

carbon cycle
Carbon Cycle
  • Marine sediments are earth’s largest store of carbon
    • Carbon is trapped between layers of sediment
    • Converted to fossil fuels when heated and compressed
phosphorous cycle
Phosphorous Cycle
  • Phosphorus
    • Helps form important molecules like DNA, RNA, and ATP
    • Inorganic phosphate PO43- is released into the soil and water as sediments wear down.
    • Eventually enters the ocean, where it is used by marine organisms
    • Does NOT include the atmosphere
phosphate cycle
Phosphate Cycle
  • Organic phosphate moves through the food web and to the rest of the ecosystem.
  • Organisms
  • Land
  • Ocean
  • Sediments
sulfur cycles through the biosphere
Sulfur Cycles through the Biosphere
  • Sulfur found in organisms, ocean sediments, soil, rocks, and fossil fuels
  • SO2 in the atmosphere
  • H2SO4 and SO4- released during volcanic eruptions (toxic)
sulfur cycles through the biosphere1
Sulfur Cycles through the Biosphere
  • Human activities affect the sulfur cycle
    • Burn sulfur-containing coal and oil
    • Refine sulfur-containing petroleum to make gasoline and other heating products
    • Convert sulfur-containing metallic mineral ores
      • Copper lead and zinc


Chapter 5

individuals in populations with beneficial genetic traits can leave more offspring
Individuals in Populations with Beneficial Genetic Traits Can Leave More Offspring
  • When environmental conditions change, populations
    • Adapt
    • Migrate
    • Become extinct
  • Genetic resistance – ability of one or more organisms in a population to tolerate a chemical designed to kill it
      • Malaria

A group of bacteria, including genetically resistant ones, are

exposed to an antibiotic

Eventually the resistant strain

replaces the strain affected by

the antibiotic

The genetically resistant bacteria

start multiplying

Most of the normal bacteria die

Normal bacterium

Resistant bacterium

geologic processes affect natural selection
Geologic Processes Affect Natural Selection
  • Tectonic plates affect evolution and the location of life on earth
    • Location of continents and oceans
    • Species physically move, or adapt, or form new species through natural selection
  • Earthquakes
  • Volcanic eruptions
extinction is forever
Extinction is Forever
  • Extinction
  • Endemic species
    • Species found only in one area
    • Particularly vulnerable
    • Golden Toad (Costa Rica) died out when habitat dried up
species diversity variety abundance of species in a particular place
Species Diversity: Variety, Abundance of Species in a Particular Place
  • Species diversity
    • Species richness – number of different species in a community
    • Species evenness – abundance of organisms within each type of species
species diversity variety abundance of species in a particular place1
Species Diversity: Variety, Abundance of Species in a Particular Place
  • Most species-rich communities
    • Tropical rain forests
    • Coral reefs
    • Ocean bottom zone
    • Large tropical lakes
worldwide richness
Worldwide Richness?
  • Diversity varies with geographical location
    • Richness is highest at tropics
    • Lowest at the poles

Question: Is productivity higher in a species-rich ecosystem?

each species plays a unique role in its ecosystem
Each Species Plays a Unique Role in Its Ecosystem
  • Generalist species
    • Broad niche
    • Live in different places, eat different food, high range of tolerance
    • Examples?
  • Specialist species
    • Narrow niche
    • More prone to extinction
    • Examples?
specialist species and generalist species niches
Specialist Species and Generalist Species Niches

Question: Is better to be a generalist or a specialist?

niches can be occupied by native and nonnative species
Niches Can Be Occupied by Native and Nonnative Species
  • Native species – organisms that normally live and thrive in a particular ecosystem
  • Nonnative species - invasive, alien, or exotic species
    • May spread rapidly
    • Not all are villains
indicator species serve as biological smoke alarms
Indicator Species Serve as Biological Smoke Alarms
  • Indicator species – species that provide early warnings of damage to a community or ecosystem
    • Can monitor environmental quality
      • Trout
      • Birds
      • Butterflies
      • Frogs
coal canaries 1800s 1900s
Coal Canaries: 1800s – 1900s
  • Coal miners took caged canaries into mines to act as early warning sentinels
  • If birds stopped singing and appeared to be distressed miners knew there were poisons being released
keystone foundation species determine structure function of their ecosystems
Keystone, Foundation Species Determine Structure, Function of Their Ecosystems
  • Keystone species – have a large effect on the types and abundances of other species in an ecosystem
    • Pollinators
    • Top predator
  • Foundation species
    • Create or enhance their habitats, which benefit others
      • Elephants
      • Beavers
endangered and threatened species are ecological smoke alarms
Endangered and Threatened Species Are Ecological Smoke Alarms
  • Endangered species – so few individual survivors that species could soon become extinct over its range
  • Threatened species- still abundant, but numbers are declining
ecological succession
Ecological Succession
  • Natural ecological restoration
    • Primary succession – gradual establishment of biotic communities in lifeless areas where there is no soil or sediment
    • Secondary succession – series of communities with different species develop in places containing only soil or bottom sediment
no population can grow indefinitely j curves and s curves
No Population Can Grow Indefinitely: J-Curves and S-Curves
  • Biotic potential – capacity for population growth under ideal conditions
    • Larger organisms tend to have low potential
population growth
Population Growth
  • Exponential growth – population that increases at a fixed rate
    • J-Curve
  • Logistic growth – rapid exponential population growth followed by a steady decrease in population growth
    • S-Curve
s curves
  • Environmental resistance – combination of all factors that act to limit the growth of a population
  • Carrying capacity (K) – maximum population of a given species that a habitat can sustain indefinitely without being degraded
phases of logistic growth curve
Phases of Logistic Growth Curve
  • Lag Phase– little initial growth.
  • Rapid Growth Phase
  • Stable Phase– stabilizing factors limit growth
species reproductive patterns
Species Reproductive Patterns
  • r-Selected species, opportunists – species with a capacity for a high rate of population increase
    • Many small offspring
    • Little to no parental care or protection
    • Reproductive opportunists
  • K-selected species, competitors – reproduce later in life and have a small number of offspring with fairly long life spans
    • Few large offspring
    • High parental care
chapter 10

Chapter 10


forests vary in their make up age and origins
Forests Vary in Their Make-Up, Age, and Origins
  • Old-growth or primary forest – uncut or regenerated primary forest that has been undisturbed for 200 years or more
    • 36% of world’s forests
    • ¾ found in Russia, Canada, Brazil, Indonesia and Papua New Guinea
forests vary in their make up age and origins1
Forests Vary in Their Make-Up, Age, and Origins
  • Second-growth forest – result from secondary ecological succession; develop after forest destruction
    • 60% of world’s forests
fire insects and climate change can threaten forest ecosystems
Fire, Insects, and Climate Change Can Threaten Forest Ecosystems
  • Surface fires
    • Usually burn leaf litter and undergrowth
      • Kill seedlings and small trees
      • Spare most mature trees; allow wildlife to escape
    • Stimulate seed germination
      • Sequoia and jack pine
    • Burn away flammable ground material
      • Prevents more destructive fires
fire insects and climate change can threaten forest ecosystems1
Fire, Insects, and Climate Change Can Threaten Forest Ecosystems
  • Crown fires
    • Extremely hot: burns whole trees
    • Kill wildlife
    • Increase soil erosion
    • Occur in forests that have not experienced surface fires for several decades
unsustainable logging is a major threat to forest ecosystems
Unsustainable Logging is a Major Threat to Forest Ecosystems
  • Increased erosion
    • Sediment runoff into waterways
  • Habitat fragmentation
    • Loss of biodiversity
  • Invasion by
    • Nonnative pests
    • Disease
    • Wildlife species
unsustainable logging is a major threat to forest ecosystems1
Unsustainable Logging is a Major Threat to Forest Ecosystems
  • Major tree harvesting methods:
    • Selective cutting
    • Clear-cutting
    • Strip cutting
we can improve the management of forest fires
We Can Improve the Management of Forest Fires
  • The Smokey Bear educational campaign
    • Forest Service and National Advertising Council
    • Convinced public that ALL forest fires are bad
      • Increases the likelihood of crown fires
      • Threaten 40% of federal forest lands from fuel buildup and slash (logging debris)
we can improve the management of forest fires1
We Can Improve the Management of Forest Fires
  • Prescribed fires – careful planning
  • Herds of goats to eat underbrush (CA)
  • Allow fires on public lands to burn
degradation of tropical forest positive feedback loop
Degradation of Tropical Forest: Positive Feedback Loop
  • Step 1: Roads
    • Cut deep into a forest for logging and settlement
    • Selective cutting; large trees fall but bring small trees with them because of vines and canopy
  • Step 2: Ranchers buy land
    • Cattle ranchers use land for grazing
    • After overgrazing herds move
  • Step 3: Settlers buy land for harvesting
    • Grow food to survive
    • Soil nutrients depleted after a few years and

land is barren

  • Rangelands – unfenced grasslands in temperate and tropical climates that supply forage (vegetation) for grazing (grass-eating) and browsing (shrub-eating) animals
  • Pastures – managed grasslands or enclosed meadows usually planted with domesticated grasses or other forage
important ecological services of grasslands
Important ecological services of grasslands
  • Soil formation
  • Erosion control
  • Nutrient cycling
  • Storage of atmospheric carbon dioxide in biomass
  • Maintenance of diversity
riparian zones
Riparian Zones
  • Thin strips of lush vegetation along streams or rivers
    • Livestock tend to aggregate around natural water sources
case study stresses on u s public parks
Case Study: Stresses on U.S. Public Parks
  • 58 Major national parks in the U.S.
  • Biggest problem may be popularity
    • Noise
    • Congestion
    • Pollution
    • Damage or destruction to vegetation and wildlife
  • Repairs needed to trails and buildings