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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/lawspolicies/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
You
Your class
Your state
United
States
Hectares of forest used for
housing
0.40
Answers will vary
Answers will vary
Total forest hectares used
120,000,000
177,000,000
0.59
Answers will vary
Answers will vary
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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 equalaged 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.
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