Chapter 6Resources 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, faster-growing 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

• 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

Air Resources

• 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

MusselsFanshell Endangered Catspaw Endangered Ring Pink Endangered Pink Mucket Endangered Little-wing Pearlymussel Endangered Orange-foot Pimpleback Endangered Rough Pigtoe Endangered Fat Pocketbook Endangered Cumberland Bean Mussel Endangered Northern Riffleshell EndangeredClubshell Endangered

Clubshell

FishBlackside Dace Threatened Palezone Shiner EndangeredPallid Sturgeon Endangered

BirdsBald 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 Threatened 

White-haired Goldenrod Threatened 

Short's Goldenrod Endangered 

Virginia Spiraea Threatened 

Running Buffalo Clover Endangered 

Chaffseed Endangered

Running Buffalo Clover

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

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

6-4 Charting a Course for the Future

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