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163 Copyright © 2011 Pearson Education, Inc 11 Biodiversity and Conservation Biology Chapter Objectives This chapter will help students: Characterize the scope of biodiversity on Earth Contrast the background extinction rate with periods of mass extinction Evaluate the primary causes of biodiversity loss Specify the benefits of biodiversity Assess the science and practice of conservation biology Analyze efforts to conserve threatened and endangered species Compare and contrast conservation efforts above the species level Lecture Outline I. Central Case: Saving the Siberian Tiger A. Up until the past 200 years, tigers roamed widely across the Asian continent, from Turkey to northeast Russia to Indonesia. B. Of the tigers that still survive in small pockets of their former range, those in the subspecies known as the Siberian tiger are the largest cats in the world. C. For thousands of years, the Siberian tiger coexisted with the native people of what is today the Russian Far East, who equated the tiger with royalty and viewed it as a guardian. D. The Russians who moved into and exerted control over the region in the early 20th century had no cultural traditions that expressed respect for the animal, causing the species to decline to as few as 20, perhaps 30, animals. E. International conservation groups began to get involved, working with Russian biologists to try to save the dwindling tiger population.

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Page 1: Biodiversity and Conservation Biologybio1110.nicerweb.com/Locked/media/doc/Withgott/...V. Conservation Biology: The Search for Solutions A. Conservation biology arose in response to

163 Copyright © 2011 Pearson Education, Inc

11 Biodiversity and Conservation Biology

Chapter Objectives This chapter will help students:

Characterize the scope of biodiversity on Earth

Contrast the background extinction rate with periods of mass extinction

Evaluate the primary causes of biodiversity loss

Specify the benefits of biodiversity

Assess the science and practice of conservation biology

Analyze efforts to conserve threatened and endangered species

Compare and contrast conservation efforts above the species level

Lecture Outline I. Central Case: Saving the Siberian Tiger

A. Up until the past 200 years, tigers roamed widely across the Asian continent,

from Turkey to northeast Russia to Indonesia.

B. Of the tigers that still survive in small pockets of their former range, those in

the subspecies known as the Siberian tiger are the largest cats in the world.

C. For thousands of years, the Siberian tiger coexisted with the native people of

what is today the Russian Far East, who equated the tiger with royalty and

viewed it as a guardian.

D. The Russians who moved into and exerted control over the region in the early

20th century had no cultural traditions that expressed respect for the animal,

causing the species to decline to as few as 20, perhaps 30, animals.

E. International conservation groups began to get involved, working with

Russian biologists to try to save the dwindling tiger population.

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F. Today, the population is in a range of 430 to 500 tigers, and 1,500 more

survive in zoos around the world.

II. Our Planet of Life

1. Biological diversity, or biodiversity, is the sum total of all organisms in

an area.

a. Biodiversity takes into account the diversity of species, their genes,

their populations, and their communities.

A. Biodiversity encompasses multiple levels.

1. Species diversity is expressed as the number or variety of species in the

world or in a particular region.

a. A species is a distinct type of organism, a set of individuals that

uniquely share certain characteristics and can breed with one another

and produce fertile offspring.

b. Speciation, the generation of new species, adds to species diversity,

while extinction decreases species diversity.

c. Taxonomists, the scientists who classify species, use an organism’s

physical appearance and genetic makeup to determine its species.

d. Biodiversity exists below the species level in the form of subspecies,

populations of a species that occur in different geographic areas and

differ from one another in some characteristics.

2. Genetic diversity encompasses the differences in DNA composition

among individuals within a given species.

a. Genetic diversity provides the raw material for adaptation to local

conditions.

b. In the long term, populations with more genetic diversity may stand

better chances of persisting, because their variation provides them

more genetic options with which to cope with environmental change.

c. Populations with little genetic diversity are vulnerable to

environmental change, because they may happen to lack genetic

variants that would help them adapt to novel conditions.

3. Ecosystem diversity, community diversity, habitat diversity, and landscape

diversity are all ways to view biodiversity.

B. Some groups hold more species than others.

C. Measuring biodiversity is not easy.

1. Many species are tiny and easily overlooked.

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2. Many organisms are so difficult to identify that ones thought to be

identical sometimes turn out, once biologists look more closely, to be

multiple species.

3. Some areas of Earth still have been hardly explored.

D. Biodiversity is unevenly distributed.

1. The latitudinal gradient influences the species diversity of Earth’s biomes.

2. For any given area, species diversity tends to increase with the diversity of

habitats, because each habitat supports a somewhat different set of

organisms.

III. Biodiversity Loss and Species Extinction

1. Extinction occurs when the last member of a species dies and the species

ceases to exist; in contrast, the extinction of a certain population from a

given area, but not the entire species globally, is called extirpation.

A. Extinction occurs naturally.

1. Most extinctions preceding the appearance of humans have occurred one

by one, at a rate that paleontologists refer to as the background rate of

extinction.

B. Earth has experienced five mass extinction episodes.

C. Humans are setting the sixth mass extinction in motion.

D. Current extinction rates are much higher than normal.

1. To keep track of the current status of endangered species, the World

Conservation Union (IUCN) maintains the Red List.

E. Biodiversity loss involves more than extinction.

F. Several major causes of biodiversity loss stand out:

1. Habitat loss

2. Invasive species

3. Pollution

4. Overharvesting

5. Climate change

6. Human Population

IV. Benefits of Biodiversity

A. Biodiversity provides ecosystem services free of charge.

B. Biodiversity helps maintain ecosystem function.

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C. Biodiversity enhances food security.

D. Organisms provide drugs and medicines.

E. Biodiversity generates economic benefits through tourism and recreation.

F. People value and seek out connections with nature.

1. Edward O. Wilson has popularized the notion of biophilia, asserting that

human beings have an instinctive love for nature and feel an emotional

bond with other living things.

G. Do we have ethical obligations toward other species?

V. Conservation Biology: The Search for Solutions

A. Conservation biology arose in response to biodiversity loss.

1. Conservation biology is a scientific discipline devoted to understanding

the factors, forces, and processes that influence the loss, protection, and

restoration of biological diversity.

B. Conservation biologists work at multiple levels.

C. Endangered species are a focus of conservation efforts.

1. The primary legislation for protecting biodiversity in the United States is

the Endangered Species Act (ESA). Passed in 1973, the Endangered

Species Act forbids the government and private citizens from taking

actions that destroy endangered species or their habitats.

D. Conservation efforts include international treaties.

1. The 1973 Convention on International Trade in Endangered Species

of Wild Fauna and Flora (CITES) protects endangered species by

banning the international transport of their body parts.

2. In 1992, the leaders of many nations agreed to the Convention on

Biological Diversity, a treaty outlining the importance of conserving

biodiversity, using it sustainably, fairly distributing its benefits, and

committing signatory nations to conserving this diversity.

E. Captive breeding, reintroduction, and cloning are being used to save species.

1. Zoos and botanical gardens have become centers for the captive breeding

of endangered species, so that large numbers of individuals can be raised

and then reintroduced into the wild.

2. The newest idea for saving species from extinction is to create individuals

through cloning.

F. Forensics is being used to protect threatened species.

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1. By analyzing DNA from organisms or their body parts sold at market,

researchers can often determine the species or subspecies of organism, and

sometimes its geographic origin. The analysis can help detect illegal

activity and enforce the laws protecting wildlife.

G. Some species act as ―umbrellas‖ for protecting habitat and communities.

H. Parks and protected areas help conserve biodiversity at the ecosystem level.

I. Biodiversity hotspots pinpoint regions of high diversity.

1. Biodiversity hotspots are areas that support an especially great diversity

of species, particularly species that are endemic to the area, or found

nowhere else in the world.

J. Innovative economic strategies are being employed.

1. One strategy is the debt-for-nature swap. In such a swap, a conservation

organization raises money and offers to pay off a portion of a developing

nation’s international debt in exchange for a promise by the nation to set

aside reserves, fund environmental education, and better manage protected

areas.

2. A newer strategy that Conservation International has pioneered is the

conservation concession. Developing nations often sell ―concessions‖ to

foreign multinational corporations, allowing them to extract resources

from the nation’s land.

K. We can restore degraded ecosystems.

L. Community-based conservation is growing.

1. In community-based conservation, biologists engage local people in

efforts to protect land and wildlife.

VI. Conclusion

A. The erosion of biological diversity could bring on a mass extinction event

equivalent to the major ones of the geological past.

B. The primary causes of biodiversity loss include habitat alteration, invasive

species, pollution, overharvesting, and global climate change.

C. Many conservation biologists are rising to the challenge with traditional and

innovative strategies to save endangered species and their habitats.

Key Terms background rate of extinction

biodiversity hotspots

biological diversity (biodiversity)

biophilia

captive breeding

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community-based conservation

conservation biology

Convention on Biological

Diversity

Convention on International

Trade in Endangered Species of

Wild Fauna and Flora (CITES)

ecological restoration

ecosystem services

Endangered Species Act (ESA)

endemic

extinction

extirpation

genetic diversity

habitat fragmentation

mass extinction

Red List

species

species diversity

Teaching Tips 1. Download the NatureServe 2002 report States of the Union: Ranking

America’s Biodiversity (www.natureserve.org/publications/statesUnion.jsp).

NatureServe ranks the 50 states and the District of Columbia based on diversity

of species, levels of rarity and risk, endemism, and number of extinct species.

Provide students with information about your state. Then ask them these

questions: How does it rank? Is the state high or low in biodiversity? High or

low in endemism? High or low in extinction rates? How does it compare to

surrounding states?

2. Assign students to research a species that is listed with the current IUCN Red

List of Threatened Species (www.redlist.org). Information is accessible via the

Red List database through a search by category, region, and/or country. Where

does the species live? What threatens the species? What is the status of the

species? What is being done to protect the species?

Species on the Red List are placed in a category based on their status : Extinct,

Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Lower

Risk, Near Threatened, and Data Deficient. A description of each category can

be found on www.redlist.org/info/categories. Ask students what they think the

categories mean and then provide them with the official definition.

3. Download an overview of the Endangered Species Act published by the U.S.

Fish and Wildlife Service (http://www.fws.gov/endangered/laws-

policies/index.html). This overview gives basic information about the ESA,

including how species become listed, a timeline of major events, how the law

is enforced, and how habitat conservation plans are implemented. Ask students

to compare the Endangered Species Act with the Red List.

4. Assign students to conduct Internet research for updates on the Siberian tiger

population. For example, they might uncover that in February 2003, a

photograph was taken of a wild Siberian tiger in northeastern China, suggesting

that the population is returning to areas it formerly populated

(www.savechinastigers.org).

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5. A consensogram is a tool that can be used in two ways: for surfacing student

misconceptions and also for sharing opinions about a controversial topic. The

instructor makes a large bar chart, either on a sheet of paper or on the board. A

question is posted above the chart, and possible answers are displayed along

the x axis. As students enter the room, have them come to the bar chart, read

the question, place a small sticky piece of paper (or fill in a square on the bar

chart) atop the bar for their answer choice, and sit down. When has all students

have made their choices, there will be a bar graph, or histogram, showing the

number of students who chose each answer. If the question is commonly

misunderstood, such as, ―Where does the material for the increase in biomass

of a growing plant come from?‖ (Possible answers: sunlight, water, soil,

carbon dioxide in the air, oxygen in the air), then this is an excellent departure

point for a lecture on plant growth and photosynthesis. If the question asks for

opinions about a topic, such as the preferred method for attempting to preserve

a particular endangered species (or not), then it can serve as a good beginning

for a class discussion as well.

Additional Resources

Websites

1. Conservation International (www.conservation.org/xp/CIWEB/)

Conservation International’s website describes its conservation regions,

strategies, and programs.

2. Convention on Biological Diversity, United Nations Environment Programme

(www.biodiv.org/default.shtml)

This UN website provides information about the Convention on Biological

Diversity, an international treaty to conserve the world’s biodiversity. The full

text of the treaty and international case studies can be accessed.

3. Invasivespecies.gov, National Agricultural Library for the National Invasive

Species Council (www.invasivespeciesinfo.gov)

This online resource gives information about federal efforts concerning

invasive species. The website also describes the impacts of invasive species

and presents species profiles.

4. National Biological Information Infrastructure (NBII), U.S. Geological Survey

(www.nbii.gov)

This website provides access to images, data, and information about the

nation’s biodiversity.

5. Publications of the IUCN—The World Conservation Union

(http://www.iucn.org/knowledge/publications_doc/publications/)

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This website, and its publications, discuss and provide information about the

efforts of the SSC to protect species worldwide.

6. The Nature Conservancy (http://nature.org)

This listing provides information about The Nature Conservancy’s programs

and success stories around the world.

7. Island Press (www.islandpress.org)

Extensive resources for text and AV resources on the science of restoration

ecology.

8. Society for Ecological Restoration International is a professional organization

for individuals involved in landscape-scale restoration. This international

organization shares information and resources with the global community on

projects ranging from wetland restoration in southern Iraq to restoring fragile

arctic tundra post–oil rig platform removal. (www.SER.org)

Audiovisual Materials

1. Before It’s Too Late, 1993, Storyteller Productions video, distributed by The

Video Project (http://www.storyteller.com.au/)

This video investigates the efforts of scientists worldwide to save endangered

species and preserve global biodiversity.

2. Natural Connections (Classroom Version), 2000, Howard Rosen Productions

video, distributed by Bullfrog Films (www.bullfrogfilms.com)

This video is divided into five programs: Introduction to Biodiversity; The

Significance of Salmon; Keystone Species; Forests, Biodiversity and You; and

Biodiversity vs. Extinction.

3. Wild Places, Scientific American Frontiers, PBS Home Video

(www.shop.pbs.org)

This episode of Scientific American Frontiers looks at the current extinction

crisis and innovative conservation strategies implemented around the world.

4. Conserving Earth’s Biodiversity, E. O. Wilson and Dan Perlman, distributed

by Island Press (www.islandpress.org)

This CD-ROM program features video clips of E.O. Wilson, interactive exercises,

case studies, and maps to introduce the topic of biodiversity and its current crisis.

Weighing the Issues: Facts to Consider Bioprospecting in Costa Rica

Facts to consider: Much of this question requires a personal response. Some

responses may indicate that this agreement is at least a starting point—a partial

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model, showing that there are constructive alternatives to bioprospecting that

benefit companies in developed nations but not the countries of origin. The

agreement does allow for a small royalty to INBio and the Costa Rican government

if a product is developed based on the original agreement; however, these royalties

transpire only if a product goes to market. Though both sides did get some benefit

in this agreement, many might argue that it would be more equitable if greater

benefits to the contracting company also led to greater benefits to the developing

country. A case study about the issue can be found in the Trade and Environment

Database (TED) of The American University

(www.american.edu/TED/MERCK.HTM).

Biophilia and Nature-Deficit Disorder

Facts to consider: Most of this question requires a personal response. To answer

the last part of the question, students may discuss how a survey might help

determine whether most people in a community have an affinity for other living

things, asking questions about recreation, values, and charitable preferences. So,

too, might a tally of how many households have pets, how well pet-supply

businesses are doing, activity levels in local parks, or participation in outdoor

recreational activities. Using a more interactive, applied approach, a day in front of

a local grocery store promoting animal adoptions with a local animal shelter might

yield interesting, even quantifiable, results.

Single-Species Conservation

Facts to consider: Answers will vary depending on background and experience.

One advantage of single-species conservation is in highlighting public awareness. A

single species provides a visible symbol for supporters to showcase in making pleas

for contributions. It is easier to show the plight of an organism with statistics and

photos rather than that of an ecosystem, especially if the organism in question is

charismatic megafauna, such as a lion, tiger, or bear. Facilities for restoring

populations can be built anywhere, and with advances in veterinary medicine and

expertise in exotic animal husbandry, most organisms respond quite well to captive

breeding programs. Finally, it is simpler to collect data to show the progress of

population restoration in captivity and in the wild.

There are, however, some disadvantages to single-species conservation. If a species

is removed from the wild because the initial population is too small, reintroduction

of the organism to the wild poses very serious problems both to the organism and to

the ecosystem. With California condors, for example, the chicks were mostly raised

by hand, and so workers had to train condors how to behave like condors and to

avoid humans, sometimes using extreme methods. From a genetic standpoint, the

species is weakened because of the small size of the gene pool. If the species is to

be reintroduced into the wild, other obstacles can arise. If the habitat is not

appropriate to the organism or not protected from direct or indirect human-induced

damage, all of the time, effort, and funding put into saving the species will be lost

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as the organism dies out. A single species is reliant on the abiotic conditions and

biotic communities with which it evolved, and so any alteration of these conditions

will select against the species being reintroduced. The conservation of charismatic

megafauna has exacerbated this as the only organisms deemed worth saving are

typically large mammals or birds, not the less charismatic vertebrates, invertebrates,

or plants. Finally, preserving and conserving habitats protects species that have yet

to be discovered, described, and studied, and may be more economically feasible in

the long term.

The Science behind the Stories:

Thinking Like a Scientist Amphibian Diversity and Decline

Observation: The rate of discovery of new amphibian species is tremendous.

Question: Does Sri Lanka have more than the 40 species of frogs already known to

live on the island?

Study: In the 1990s, Madhava Meegaskumbura and his team spent eight years

collecting frogs from 300 study sites and compared a variety of their physical,

behavioral, and genetic traits to the same traits of previously identified Sri Lankan

frog species.

Results: More than 100 new species of amphibians were found.

Observation: At the same time that the Meegaskumbura team showed the

scientific community that there were still many amphibian species yet to be

discovered, populations of many other amphibians were decreasing at alarming

rates, some with no apparent cause for the decline. Researchers’ main concern was

that amphibians were being affected by a combination of harmful environmental

conditions.

Question: What may have caused such drastic decreases in amphibian populations?

Hypothesis: Because all amphibians breathe and absorb water through their skin at

some stage of their life, they are sensitive and vulnerable to individual or a

combination of external environmental stressors.

Experiment: Rick Relyea and Nathan Mills conducted an experiment that exposed

young frogs—tadpoles—to two environmental stressors: predators and pesticides.

These researchers had three groups of tadpoles: tadpoles exposed only to pesticides,

tadpoles exposed only to predators, and tadpoles exposed to both pesticides and

predators. Joseph Kiesecker conducted a similar experiment, exposing frogs to

pathogens and pesticides.

Results: The experiments yielded similar results. Combinations of environmental

stresses have the greatest influence on the death rate of the frogs tested. In Relyea

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and Mills’s study, tadpoles exposed to low levels of pesticide and the presence of

predators had a 25% lower survival rate than if only the pesticide was present. In

Kiesecker’s study, frogs were more susceptible to parasitic infections if also

exposed to pesticides in water. While these studies do not define a specific cause

for amphibian population decline, the research does point to combinations of

environmental conditions having the most influence over amphibian survivorship.

Using Forensics to Uncover Illegal Whaling

Observation: Conservation biologists long suspected that much of the whale meat

on the market was actually caught illegally for the purpose of selling for food, and

that fleets from nations such as Japan were killing more whales than international

law allowed.

Question: Is all whale meat sold in Japan caught legally?

Hypothesis: Illegal samples would be found on grocery store shelves in Japan,

labeled generically as whale meat.

Experiment: Baker and Palumbi bought samples of whale meat—all labeled

simply as kujira, the generic Japanese term for whale meat—from a number of

markets in Japan. They sequenced DNA from these samples.

Results: It was concluded that they had sampled meat from 9 minke whales, 4 fin

whales, 1 humpback whale, and 2 dolphins. One fin whale came from the Atlantic

whereas the other 3 were from the Pacific, and 8 of the 9 minke whales came from

the Southern Hemisphere. Because several of these species and/or subspecies were

off-limits to hunting, the data suggested that some of the meat had been hunted,

processed, or traded illegally.

Observation: Two years later, Baker, Palumbi, and Cipriano presented results

from markets in South Korea and Japan. Again their genetic sleuthing revealed a

diversity of whale species, and they stated that their data were ―difficult to

reconcile‖ with records of legal catches (scientific whaling by Japan and fishing

bycatch by South Korea) reported by these nations to the IWC. Among the whales

they detected were two specimens of what seemed to be a subspecies or species of

whale new to science.

Question: Was illegal fishing continuing, and was this illegal catch still being sold

on grocery shelves?

Hypothesis: Illegal harvest of meat was continuing in South Korea and Japan.

Experiment: In 2000, the team analyzed 655 samples from Japanese and South

Korean markets.

Results: Evidence was found of 12 species or subspecies of whales, along with

orcas, porpoises, and dolphins—and even sheep and horses! Seven of the whale

species were internationally protected, and together these constituted 10% of the

whale meat for sale in Japanese markets. In 2007, Baker led a team that combined

genetic forensics with ecological methods to estimate numbers of individual whales

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whose meat was passing through Korean markets. They inferred that meat from 827

minke whales had passed through South Korea’s market in five years. The nation

had reported catching only 458 minke whales as fishing bycatch, leading the

researchers to conclude that the remainder had been taken illegally.

Answers to End-of-Chapter Questions Testing Your Comprehension

1. Biodiversity has no single definition. At the species level, it refers to both the

number of different species present in an area and to the evenness or relative

abundance of those species. At the genetic level, it refers to the genetic variety

within a single species. At the ecosystem level, it refers to the number and

variety of ecosystems in an area. The concept may be applied at the

community, habitat, and landscape levels as well.

2. Habitat alteration, invasive species, pollution, overexploitation, and climate

change are all causes of biodiversity loss. Examples, in the order of the factors

just mentioned, are hydroelectric dams altering stream habitat, zebra mussels in

the Great Lakes, air pollution killing forest trees, Siberian tigers being hunted

to near extinction, and climate change affecting the cloudforest fauna in

Monteverde.

3. The zebra mussel (a small, striped mollusk), has spread rapidly through eastern

North American waterways, fouling ship motors, pumps, docks, and so on.

Feral pigs in Hawaii alter the habitat for mosquitoes, increasing the invasive

mosquito species Culex quinquefasciatus, which spreads avian malaria and

avian pox diseases among the native bird populations. Humans are an invasive

species, too. We’ve transported many agricultural species, as well as many

weeds, some of which have naturalized in their new habitats, thus altering the

local ecological balance.

4. Processes provided by ecosystems, such as air and water purification, are called

ecosystem services. Other than those just mentioned, ecosystems also: provide

food, fuel, and fiber; detoxify and decompose waste; and stabilize and

moderate Earth’s climate.

5. Biodiversity increases food security by providing the genetic diversity for

species to adapt to a wide range of growth conditions, and by providing

potential new species for cultivation. Salt-tolerant plants that produce animal

feed, vegetable oil, and wood may increase the food supply and prosperity of

the world’s poor living in areas with saline soils, for instance. Many

pharmaceuticals are derived from wild species, and many more are awaiting

discovery. Australia has an active research program to survey its unique biota

for useful pharmaceuticals, and has found the compounds hycoscine, salsodine,

and prostaglandin E2, among others.

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6. Biodiversity provides valuable ecosystem services free of charge. It helps

maintain ecosystem function, provides natural classrooms, enhances food

security, provides economic benefits through tourism and recreation, and

provides traditional medicine and high-tech pharmaceuticals.

7. The U.S. Endangered Species Act (ESA) has resulted in the rebounding

populations of the peregrine falcon, brown pelican, and bald eagle, all of which

have been removed from the endangered species list. Fully 40% of species with

declining populations have been stabilized. The ESA has been criticized for

valuing endangered species above the livelihood of humans, and because of

fears that it will unreasonably restrict the use of private land.

8. Captive breeding can offer controlled conditions such as protected habitats,

lack of natural predators, and a steady supply of food. This could benefit many

populations. For example, in 1982, the population of the California condor,

North America’s largest bird, had dwindled to only 22 animals in the wild, but

rebounded in 2010 to 176 in captivity and 180 in the wild after the help of a

captive breeding program. At this point, maintaining a species by cloning is

not a viable alternative, as without ample habitat and protection in the wild,

having cloned animals in a zoo does little good.

9. An “umbrella” species requires large areas of habitat. If sufficient habitat is

protected to preserve that umbrella species, many other species with smaller

habitat requirements will also benefit. A “keystone” species is one that plays a

crucial role in the trophic web of an ecosystem. Since keystone species are

often top predators that require a large area of habitat, they can be both

keystone and umbrella species.

10. In a debt-for-nature swap, a conservation organization raises money and offers

to pay off a portion of a developing nation’s international debt in exchange for

a promise by the nation to set aside reserves, fund environmental education,

and better manage protected areas. In a conservation concession, developing

nations often sell ―concessions‖ to foreign multinational corporations, allowing

them to extract resources from the nation’s land.

Calculating Ecological Footprints

Hectares of forest used for

housing

Total forest hectares used

You 0.40 0.59

Your class Answers will vary Answers will vary

Your state Answers will vary Answers will vary

United

States 120,000,000 177,000,000

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1. The majority of the remainder of forest product use is wood pulp for the

production of paper and packaging materials.

2. If a forest is harvested at greater than its sustainable rate, the result will be a

decrease in the standing stock of forest materials. This will eventually result in

deforestation. For communities in the area, this will likely mean a loss of jobs

in the local timber industry and a loss of jobs in other sectors that depend on the

forest, including ecotourism. Erosion and pollution may increase, and quality of

life and land and housing values may decrease.

3. If the plots are large enough to fragment the forest, then species that depend on

intact forest habitat will decline or disappear. If the plots are small, then species

that thrive in gaps in the forest may increase, and local species richness may

even increase. (b) Clear-cutting will completely change the array of organisms

present in an area, killing or driving out all forest-dependent species, and

providing habitat for a considerably smaller array of species that can thrive in

clear-cuts. (c) Simplification of a forest into a plantation monoculture of equal-

aged trees greatly reduces the diversity of niches available, and thereby reduces

the species diversity of the forest community considerably. Spatial scale makes

a difference in all of these instances, for example, for part (a). Moreover, the

greater the scale over which forest loss or habitat occurs, the more likely species

are to be lost from entire regions.