Chapter 6
Resources and Conservation
6-2 Renewable and Nonrenewable Resources
Classifying Resources
• Renewable Resources – can regenerate if they
are alive, or can be replenished by biochemical
cycles if they are nonliving
• Example: tree, water, air, solar
• Nonrenewable Resources – cannot be
replenished by natural processes
• Once these fuels are depleted they are gone
forever
• Example: coal, oil, natural gas
Sustainable
Development
• Sustainable
Development – a way
of using natural
resources without
depleting them and
causing long-term
environmental harm
Forest Resources
•
Earth’s forests are an important resource for the
products they provide and for the ecological
functions they perform.
•
•
•
•
•
•
•
Provide wood for products and fuel.
Remove carbon dioxide and produce oxygen.
Store nutrients.
Provide habitats and food for organisms.
Moderate climate.
Limit soil erosion.
Protect freshwater supplies.
•
Whether a forest can be considered a
renewable resource depends partly on the
type of forest.
•
Temperate forests of the Northeast are
renewable because they have been logged
and have grown back naturally.
•
Old-growth forests, such as those in Alaska
and the Pacific Northwest, are nonrenewable
because it takes centuries to produce them.
•
Deforestation
• Loss of forests, or deforestation, has several
effects:
• Erosion can wash away nutrients in the topsoil.
• Grazing or plowing can permanently change local
soils and microclimates, which prevents the
regrowth of trees.
•
Forest Management
• Mature trees can be harvested selectively to
promote the growth of younger trees and
preserve the forest ecosystem.
• Tree geneticists are breeding new, fastergrowing trees that produce high-quality wood.
Fishery Resources
•
Fishes and other animals that live in water are a
valuable source of food.
•
Overfishing
• Harvesting fish faster than they can reproduce
• Has greatly reduced the amount of fish in parts of the
world’s oceans
• Fisheries seemed to be a renewable resource, but
overfishing has limited that resource
•
U.S. National Fisheries Service has issued
guidelines that specify how many fish, and of
what size, can be caught
Air Resources
• Smog – a mixture of chemicals that occurs as
a gray-brown haze in the atmosphere
• Is due to automobile exhausts and
industrial emissions
• Considered a pollutant because it
threatens people’s health
• Pollutant – a harmful material that can enter
the biosphere through the land, air, or water
• The burning of fossil fuels can release
pollutants that cause smog and other
problems in the atmosphere
•
Strict automobile emissions standards and
clean-air regulations have improved air
quality in many cities, but air pollution is
still a problem.
•
Acid precipitation – nitrogen and sulfur
compounds in the atmosphere combine
with water vapor and fall to the Earth in the
form of rain, snow, sleet, or fog
•
Acid precipitation kills plants by damaging
their cells and interfere with plant growth
Freshwater Resources
•
Although water is a renewable resource,
the total supply of fresh water is limited
and is threatened by pollution.
•
Sources of freshwater pollution include:
• Improperly discarded chemicals that enter
streams and rivers.
• Wastes discarded on land that seep through soil
and enter underground water supplies.
• Domestic sewage containing compounds that
encourage growth of algae and bacteria.
• Sewage containing microorganisms that spread
disease.
•
Sustainable Use of Water
• One way to ensure the sustainable use of
water is to protect the natural systems
involved in the water cycle that help purify
water.
• Examples:
• wetlands
• forests
• rock layers
• Also, by conserving water in:
• home
• industry
• agriculture
The Fate of Spilled Oil
• According to a well-known saying that oil and water
don’t mix, it might be expected that spilled oil would
float around until it was washed ashore
• A single gallon of oil can spread enough to cover up
to four acres of water
• As soon as the oil is spilled in a marine environment,
many changes begin to take place
• Within days, 25% of the oil is lost through
evaporation
• The remaining oil sinks to the bottom of the ocean
• It adheres to almost all objects that it encounters
• After 3 months only 15% of the original oil remains
• If a substantial oil spill occurred close to shore
rather than at sea, the effects would be
different because there would not be sufficient
time available for the process described above
to affect the total amount of oil involved
Effects of Oil Spills
1. Reduction of Light Transmission
• Light intensity 2m below an oil slick can be
reduced by 90%
• Reduces the rate of photosynthesis so
plants and protists die
2. Reduction in Dissolved Oxygen
• Oil film blocks rate of oxygen uptake by water
• DO is lower in oil contaminated water
3. Damage of Marine Birds
• Birds covered with oil can drown
• Oil causes bird feathers to mat together and
reduces the birds ability to fly and float in water
• Feathers lose their insulating ability
• Birds die because of exposure to cold weather or
inability to get food
4. Toxic Effects to Marine Environment
• Oil contains benzene, toluene, xylene,
which are toxic to plants and animals
Methods of Oil Spill Clean-Up
• Booms or Barriers
• Contain oil slick
• Makes it easier to skim the oil off the surface
• Skimmers
• Used to remove oil from the surface of the water
• They are attached to ships or may be hand-held
along shore
• Skimming works best in calm waters
• Sorbents
• Materials used to soak up oil spills
• Example: straw, powdered clay, sawdust, chopped corn
cobs, pine bark
• Chemical Dispersants, Detergents, and Solvents
• Used to degrade the oil
• Unfortunately most of these chemicals are toxic to
animals
• Flames
• Used to burn the oil
• The black smoke contains toxic components
Bioremediation
• The oil spill cleanup methods listed above only
recover 10-30% of the spilled oil
• The most environmentally safe prospect for the
cleanup of oil spills is the use of oil-degrading
microbes
• Bioremediation – the use of naturally occurring
microorganisms that have been genetically
engineered and that can be used to degrade
petroleum products
• A microorganism called petrophiles are spread across
an oil spill and they degrade the oil and convert it into
food
• The microorganisms may be mixed with
nutrients such as nitrogen, phosphorus, and
cottonseed protein that not only enhance the
microbial growth, but also absorb the oil and
provide a matrix for the microorganisms to
continue to degrade the absorbed oil
• The treated oil slick begins to break up and
turn into a yellowish substance that
eventually diminishes in size
Case Study – The Exxon Valdez
• In the spring of 1989, the largest oil spill in
U.S. history occurred when an oil tanker
named the Exxon Valdez hit a reef in Prince
William Sound off the coast of Alaska
• More than 10 million gallons of crude oil
spilled
• The oil slick covered more than 1,000 miles
of coastline
• Caused an estimated 5 billion dollars in
environmental damages
• The Exxon Valdez disaster killed more
wildlife than any other environmental
disaster in our nation’s history
• 250,000 seabirds died
• 2,800 sea otters died
• 300 harbor seals died
• 250 bald eagles died
• 22 killer whales died
6-3 Biodiversity
•
The Value of Biodiversity
• Biodiversity – the number of species that live
in a certain area
• A rain forest has the greatest amount of
biodiversity.
• Why is biodiversity important?
• Food
• Medicines
• Industrial products
•
•
Threats to Biodiversity
Human activity can reduce biodiversity
by:
• altering habitats
• hunting species to extinction
• introducing toxic compounds into food webs
• introducing foreign species to new
environments
• Threatened species – when the population of a
species begins declining rapidly
• Endangered Species – when species numbers
become so low that extinction is possible
• Extinction – the disappearance of a species when the
last of its members dies
• Since 1980’s almost 40 species of plants and animals
living in the United States have become extinct
• Although extinction can occur as a result of natural
processes, humans have been responsible for the
extinction of many species
Mussels
Fanshell
Catspaw
Ring Pink
Endangered
Endangered
Endangered
Pink Mucket
Little-wing Pearlymussel
Orange-foot Pimpleback
Rough Pigtoe
Endangered
Endangered
Endangered
Endangered
Fat Pocketbook
Cumberland Bean Mussel
Northern Riffleshell
Endangered
Endangered
Endangered
Clubshell
Endangered
Clubshell
Fish
Blackside Dace
Threatened
Palezone Shiner
Endangered
Pallid Sturgeon
Endangered
Birds
Bald Eagle
Endangered
Red-cockaded Woodpecker
Endangered
Interior Least Tern
Endangered
Passenger Pigeon
Extinct
Mammals
Gray Myotis (bat)
Endangered
Indiana Myotis (bat)
Endangered
Virginia Big-eared Bat
Endangered
Siberian Tiger
Endangered
Tasmanian Tiger
Extinct
Plains Zebra
Extinct
Insects
American Burying Beetle
Endangered
Plants
Price's Potato-bean
Threatened
Cumberland Sandwort
Endangered
Cumberland
Rosemary
Running Buffalo Clover
Threatened
White-haired Goldenrod
Threatened
Short's Goldenrod
Endangered
Virginia Spiraea
Threatened
Running Buffalo Clover
Endangered
Chaffseed
Endangered
Chaffseed
Cumberland Rosemary
Habitat Alteration
• Habitat loss is the biggest threat to
biodiversity
• Habitat Fragmentation – the separation of
wilderness areas from other wilderness areas
• Presents problems for organisms that
need large areas to gather food
• Habitat Degradation – the damage to a habitat
by pollution
•
Introduced Species
• Another threat to biodiversity comes from plants and
animals that humans transport around the world
either accidentally or intentionally.
• Exotic (Invasive) species – organisms that are not
native to a particular area
• Reproduce rapidly because their new habitat lacks
the predators that would control their population
• Example: zebra mussels, amur honeysuckle, kudzu,
cane toad, European starling, mongoose in Hawaii
Conservation Biology
• Conservation – the management of natural
resources, including the preservation of habitats and
wildlife
• Many species are in danger due to the actions of
humans, so working with people is an important part
of conservation biology
Strategies for Conservation
• Many conservation efforts are aimed at managing
individual species to keep them from becoming
extinct
• U.S. Endangered Species Act – this law made it illegal
to harm any species on the endangered or threatened
species lists
• Create more natural preserves
• Reintroduction programs – release organisms into an
area where their species once lived
• Examples: California condor, wolves in
Yellowstone, Black-footed ferret
6-4 Charting a Course for
the Future
Ozone Depletion
• Ozone Layer – atmospheric layer in which
ozone gas is relatively concentrated
• The ozone layer absorbs a good deal of
harmful ultraviolet or UV radiation from
sunlight before it reaches Earth’s surface
Early Evidence
• In the 1970’s, scientists discovered a hole in
the ozone layer over Antarctica
• In 1974, a research team published data
showing that gases called
chloroflurocarbons, or CFC’s could damage
the ozone layer
• CFC’s were once widely used:
• As propellants in aerosol cans
• As coolant in refrigerators, freezers, and air
conditioners
• In the production of plastic foams
• The U.S. and other nations began reducing the use of
CFC’s in 1987, and eventually banned them
• Since the ban the level of CFC’s in the atmosphere
had decreased, indicating that the ban will have
positive, long-term effects on the global environment
• Current data predict that the ozone holes should
shrink and disappear within 50 years
Global Climate Change
• Since the lat 19th century, average
temperatures have risen about 0.6ºC
• Global Warming – the increase in the average
temperature of the biosphere
• One sign of global warming is melting polar
ice
Evidence of Global Warming
• The geological record shows that Earth’s climate has
changed repeatedly during its history
• Researchers must determine whether the current warming
trend is part of a larger, natural cycle of climate change, or
whether it is caused by human activity
• A widely accepted hypothesis is that current warming is
related, in part, to human activities that add carbon dioxide
and other greenhouse gases to the atmosphere
• Data show that concentrations of carbon dioxide in the
atmosphere have been rising for 200 years
• As a result, the atmosphere’s natural greenhouse effect is
intensified, causing the atmosphere to retain more heat
Possible Effects of Global Warming
• Most recent computer models suggest that average
global surface temperatures will increase by 1 to 2ºC
by the year 2050
• Sea levels may rise enough to flood coastal areas,
affecting coastal ecosystems as well as human
communities
• Parts of North America may experience more
droughts during the summer growing season
• New organisms may be able to live in places where
they once could not
• Other organisms may become threatened or extinct in
areas where they once thrived