Conservation Biology

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Conservation Biology
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57 Conservation Biology

• 57.1 What Is Conservation Biology?
• 57.2 How Do Biologists Predict Changes in
  Biodiversity?
• 57.3 What Factors Threaten Species Survival?
• 57.4 What Strategies Do Conservation Biologists
  Use?

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57.1 What Is Conservation Biology?

• Conservation biology is an applied science,
  devoted to preserving the diversity of life.
• Conservation biology is integrated with other
  disciplines, using knowledge from genetics,
  evolution, population ecology, biogeography,
  wildlife management, economics, and sociology.

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57.1 What Is Conservation Biology?

• Conservation biology is a normative discipline
  it embraces certain values and applies scientific
  methods to achieve goals related to those values.
• Conservation biologists are motivated by the
  belief that loss of biodiversity is negative.
• Although scientists are supposed to be neutral,
  most applied sciences are normative. The
  scientists must still adhere to standard
  scientific methods.

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57.1 What Is Conservation Biology?

• Conservation biology is guided by the following
  three principles
• Evolution is the process that unites all of
  biology.
• The ecological world is dynamic.
• Humans are part of ecosystems.

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57.1 What Is Conservation Biology?

• Human beings have caused extinctions of other
  species for thousands of years.
• When humans first arrived in North America 20,000
  years ago, they probably caused the extinction of
  large mammals such as camels, horses, mammoths,
  and giant sloths.
• A similar extinction occurred in Australia 40,000
  years ago.

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Figure 57.1 Extinct Australian Megafauna
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57.1 What Is Conservation Biology?

• When Polynesian people settled Hawaii 2,000 years
  ago, they exterminated at least 39 endemic
  species of birds (species found nowhere else in
  the world).

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57.1 What Is Conservation Biology?

• But the current extinction situation is unique.
• For the first time, all major environmental
  changes on Earth are human induced, and we are
  aware of what we are doing.

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57.1 What Is Conservation Biology?

• Why do we value biodiversity?
• We depend on other species for food, fiber, and
  medicines.
• Species are necessary for the functioning of
  ecosystems which provide us with so many goods
  and services.
• We derive enormous aesthetic pleasure from
  watching and interacting with other species.

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57.1 What Is Conservation Biology?

• Extinctions deprive us of the opportunity for
  scientific study and understanding ecological
  interactions.
• Extinctions raise many ethical concerns all
  species are judged to have intrinsic value.

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57.2 How Do Biologists Predict Changes in
Biodiversity?

• Scientists cannot accurately predict the number
  of extinctions in the coming century for four
  reasons
• The number of species currently on Earth is
  unknown.
• We do not know exactly where species live.

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57.2 How Do Biologists Predict Changes in
Biodiversity?

• It is difficult to determine when a species
  actually becomes extinct.
• We do not know what will happen in the future,
  including natural events, and what humans will
  do.

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57.2 How Do Biologists Predict Changes in
Biodiversity?

• Our planet is not well understood or explored.
• In 2004, the ivory-billed woodpecker was believed
  to have been glimpsed in Arkansas after 60 years
  without a siting.

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Figure 57.2 Back from Extinction?
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57.2 How Do Biologists Predict Changes in
Biodiversity?

• Rates of extinction are estimated in several
  ways.
• The speciesarea relationship is a
  well-established tool. As area decreases, number
  of species decreases.
• On average, a 90 percent loss in habitat will
  result in a 50 percent loss of species.

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57.2 How Do Biologists Predict Changes in
Biodiversity?

• The current rate of loss of tropical evergreen
  forest (the most species-rich biome) is about 2
  percent per year.
• If this rate of loss continues, at least 1
  million species will be lost from this biome in
  this century.

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Figure 57.3 Deforestation Rates are High in
Tropical Forests
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57.2 How Do Biologists Predict Changes in
Biodiversity?

• Biologists use computer models to estimate the
  probability that a population will go extinct.
• Species in imminent danger of extinction are
  labeled endangered.
• Threatened species are likely to become
  endangered in the near future.

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57.2 How Do Biologists Predict Changes in
Biodiversity?

• Species whose populations are suddenly shrinking
  are at high risk. Also species with highly
  specialized food or habitat requirements.
• Small populations can easily be wiped out by
  natural disasters, such as fire.
• Example the golden toad in Costa Rica.

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Figure 33.16 Diversity among the Amphibians (B)
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57.3 What Factors Threaten Species Survival?

• Human activities that threaten survival of other
  species include the following
• Habitat destruction
• Introduction of exotic species
• Overexploitation
• Climate change

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57.3 What Factors Threaten Species Survival?

• Habitat loss is the most important cause of
  endangerment in the U.S., especially in
  freshwater.
• As habitat is progressively lost, remaining
  habitat patches get smaller and more isolated
  habitat is increasingly fragmented.

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Figure 57.4 Proportions of U.S. Species Extinct
or Threatened
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57.3 What Factors Threaten Species Survival?

• Small habitat patches cannot maintain populations
  of species that require large areas.
• Small patches can support only small populations
  (greater risk of extinction).
• As patch size decreases, it has more edge.
  Factors originating outside the patch can have
  more influence.

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Figure 57.5 Edge Effects
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57.3 What Factors Threaten Species Survival?

• Some edge effects
• In forest patches, winds are stronger,
  temperatures higher, humidity lower, and light
  levels higher than farther inside.

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57.3 What Factors Threaten Species Survival?

• In a tropical evergreen forest in Brazil,
  research was conducted before logging began. Land
  owners agreed to leave forested patches of
  different sizes.
• Monkeys that travel over large areas were the
  first species eliminated. Next were army ants,
  then the birds that follow army ant swarms.

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Figure 57.6 Species Losses Have Been Studied in
Brazilian Forest Fragments
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57.3 What Factors Threaten Species Survival?

• When species are lost from small habitat patches,
  recolonization is unlikely. Dispersing
  individuals are not likely to find isolated
  habitat patches.
• Species may be able to persist in small habitat
  patches if there are corridors connecting patches.

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57.3 What Factors Threaten Species Survival?

• Corridors have been studied experimentally in
  pine forests.
• Eight sites were established to test whether
  bluebirds used corridors.

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Figure 57.7 Habitat Corridors Facilitate Movement
(Part 1)
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Figure 57.7 Habitat Corridors Facilitate Movement
(Part 2)
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57.3 What Factors Threaten Species Survival?

• Until recently, humans caused extinctions mainly
  by overhunting.
• Some species are still threatened today.
  Elephants and rhinoceroses are killed for their
  tusks and horns.
• Powdered rhinoceros horn is used in traditional
  Chinese medicine. An attempt to replace it with
  saiga antelope horn worked so well that it is now
  endangered.

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Figure 57.8 Endangered by Medical Practices
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57.3 What Factors Threaten Species Survival?

• Humans move many species to regions outside their
  original range, both intentionally and
  accidentally.
• Some exotic species become invasive. They spread
  widely and become extremely abundant, often at a
  cost to native species.

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57.3 What Factors Threaten Species Survival?

• There are countless examples, such as rabbits,
  introduced to Australia for sport hunting. Many
  small marsupials have been exterminated by
  competition with rabbits and predation by
  introduced cats, dogs, and foxes.
• The brown tree snake arrived on Guam in the
  1940s, and has now reached very high densities
  and caused the extinction of 15 bird species,
  including three endemics.

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Figure 57.9 Agent of Extinction
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57.3 What Factors Threaten Species Survival?

• Invasive species can include pathogens such as
  the chestnut blight and Dutch elm disease of
  trees.
• In Hawaii, avian malaria has eliminated native
  bird species living below 1,500 m elevation. The
  range of mosquitoes that transmit the disease may
  move upward with climate warming.

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57.3 What Factors Threaten Species Survival?

• Global warming will increase average temperatures
  by 2C5C by the end of this century.
• Species will have to shift ranges to remain in
  the same temperature regimes.
• Some habitats, such as alpine tundra, may be
  completely eliminated.

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57.3 What Factors Threaten Species Survival?

• In order to understand and predict future shifts,
  biologists study how species ranges shifted
  during the last 10,000 years of post-glacial
  warming.
• Species that are able to disperse quickly, such
  as birds, may be able to shift their range
  quickly if suitable habitat is available.
  Sedentary species are likely to shift much more
  slowly.

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57.3 What Factors Threaten Species Survival?

• Global warming may result in entirely new
  climates.
• A warming of 2C in tropical low elevations will
  result in a climate warmer than anywhere in the
  humid tropics today.
• Warmer nights have already been documented at
  several sites. Trees use more energy reserves,
  and growth rates have slowed.

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57.3 What Factors Threaten Species Survival?

• Increasing sea surface temperatures are
  threatening corals.
• High temperatures cause them to expel their
  photosynthetic endosymbiotic dinoflagellatescalle
  d bleaching. Death can result.
• Forty percent of coral reefs worldwide are likely
  to be killed off by 2010.

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Figure 57.10 Global Warming Threatens Corals
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57.4 What Strategies Do Conservation Biologists
Use?

• Establishing protected areas is an important part
  of efforts to preserve biodiversity.
• Protected areas preserve habitat and prevent
  human exploitation.
• They can act as nurseries from which individuals
  can disperse, replenishing populations that might
  otherwise go extinct.

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57.4 What Strategies Do Conservation Biologists
Use?

• The UN Convention on Biodiversity at the Earth
  Summit in 1992 stated
• The fundamental requirement for the conservation
  of biological diversity is the in situ
  conservation of ecosystems and natural habitats
  and the maintenance and recovery of viable
  populations of species in their natural
  surroundings.

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57.4 What Strategies Do Conservation Biologists
Use?

• Some areas are selected for protection based on
  species richness and number of endemic species.
• Biodiversity hotspots have been identified.
  They occupy 15.7 percent of Earths surface but
  have 77 percent of terrestrial vertebrate
  species.
• Most are also areas with high human populations
  and pressures.

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Figure 57.11 Hotspots of Avian Biodiversity
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57.4 What Strategies Do Conservation Biologists
Use?

• But many other areas are also important
  biologically.
• World Wildlife Fund identified 200 ecoregions of
  conservation importance.
• Many are regions that are missed by the hotspot
  approach.

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Figure 57.12 The Global 200 Ecoregions
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57.4 What Strategies Do Conservation Biologists
Use?

• After areas are identified, a conservation
  strategy must be developed.
• Conservation biologists make detailed analyses of
  the area and species present, then work with
  local people, experts, and others, to develop an
  action plan.

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57.4 What Strategies Do Conservation Biologists
Use?

• Conservation biologists have identified 595
  centers of imminent extinction which have
  threatened species found nowhere else.
• The sites harbor 794 species considered to be at
  serious risk of extinction.
• Only one-third of the sites are legally
  protected. Most are surrounded by rapid human
  development and are in urgent need of protection.

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Figure 57.13 Centers of Imminent Extinction
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57.4 What Strategies Do Conservation Biologists
Use?

• Some degraded ecosystems can be restored.
• In restoration ecology, methods are being
  developed to restore degraded habitats.
• Many grasslands have rich soils, and have been
  converted to agriculture.

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57.4 What Strategies Do Conservation Biologists
Use?

• A large prairie restoration project is underway
  in Montana. 15,000 km2 will be returned to native
  prairie plants and animals.
• The region was never plowed, so native vegetation
  should recover rapidly.
• The ranchers who own the land are retiring and
  their children are not interested in continuing
  the ranches.

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Figure 57.14 An American Prairie Is Being Restored
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57.4 What Strategies Do Conservation Biologists
Use?

• Bison, prairie dogs, and black-footed ferrets
  will be reintroduced.
• Prairie dogs dig extensive burrows and manipulate
  vegetation, supporting dozens of birds and other
  species.
• The restored prairie is expected to draw
  ecotourists, which will also improve the economy
  of the region.

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57.4 What Strategies Do Conservation Biologists
Use?

• Restoration often requires restoring disturbance
  patterns.
• Many species depend on disturbances such as fire,
  windstorms, grazing.
• Humans often try to reduce such disturbances. For
  example fire suppression was official policy for
  many years. Controlled burning is now used in
  many forest and grassland management programs.

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57.4 What Strategies Do Conservation Biologists
Use?

• Conservation biologists try to determine the
  historical patterns of disturbance.
• Annual rings of trees reveal scars from fires
  that were not intense enough to kill the trees.
• One such study near Los Alamos, NM revealed that
  low-intensity ground fires were frequent before
  about 1900.

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Figure 57.15 The Frequency and Intensity of Fires
Affect Ecosystems (A)
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57.4 What Strategies Do Conservation Biologists
Use?

• Then, grazing and fire suppression reduced
  frequency of low-intensity fires.
• Dead branches, needles, and other litter
  accumulate and when a fire does occur, there is a
  great deal of fuel available. The result is that
  fires are more likely to be intense canopy fires
  that kill trees.

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Figure 57.15 The Frequency and Intensity of Fires
Affect Ecosystems (B)
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57.4 What Strategies Do Conservation Biologists
Use?

• Although new habitats can be created, developing
  a fully functioning ecosystem that supports many
  species is not easy.
• Many development projects destroy habitat, but
  they are permitted as long as the developer
  promises to create new habitat to replace the one
  being destroyed.

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57.4 What Strategies Do Conservation Biologists
Use?

• Early wetlands restoration projects in southern
  California planted a few, easily grown species
  new wetlands failed to establish.
• Experimental work showed that species-rich
  mixtures were necessary to provide complex
  habitat for insects and birds. Nitrogen also
  accumulated faster.

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Figure 57.16 Species Richness Enhances Wetlands
Restoration (Part 1)
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Figure 57.16 Species Richness Enhances Wetlands
Restoration (Part 2)
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57.4 What Strategies Do Conservation Biologists
Use?

• Consumers can influence exploitation of species.
• The Forest Stewardship Council certifies forest
  products that have been harvested sustainably and
  in ways that protect biodiversity. Consumers can
  look for the FSC certification when purchasing
  forest products.

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57.4 What Strategies Do Conservation Biologists
Use?

• A Marine Stewardship Council was formed to
  certify marine products, from combined efforts of
  the World Wildlife Fund and Unilever.
• Australian rock lobster and Alaskan salmon have
  been certified.

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57.4 What Strategies Do Conservation Biologists
Use?

• The Convention on International Trade in
  Endangered Species (CITES) is an international
  treaty to decrease trade in endangered species,
  or any parts of these speciese.g., whale meat,
  rhinoceros horn, parrots, orchids, etc.
• For some items, such as elephant ivory, the
  demand remains strong, so poaching is common.

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57.4 What Strategies Do Conservation Biologists
Use?

• Sources of elephant tusks can now be pinpointed
  by matching microsatellite DNA markers from feces
  to those in tusks.

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57.4 What Strategies Do Conservation Biologists
Use?

• The best way to control invasive species is to
  prevent their introduction.
• Many aquatic species have been carried
  unintentionally in ship ballast water. This water
  could be deoxygenated, which would kill any
  organisms, and also extend the life of ballast
  tanks.

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57.4 What Strategies Do Conservation Biologists
Use?

• The American horticultural industry has crafted a
  voluntary code of conductthe invasive potential
  of a plant must be thoroughly researched before
  an introduction.
• Stocks of invasives will be phased out, and
  gardeners will be encouraged to use noninvasive
  species.

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57.4 What Strategies Do Conservation Biologists
Use?

• Traits that make a plant likely to become
  invasive include high growth rate, short
  generation time, small seeds, dispersal by
  vertebrates, large native range, dependent on
  nonspecific mutualists, not evolutionarily
  related to plants in the new area.
• A decision tree has been developed to help
  determine whether a species should be allowed
  into North America.

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Figure 57.17 A Decision Tree for Exotic Species
(Part 1)
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Figure 57.17 A Decision Tree for Exotic Species
(Part 2)
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57.4 What Strategies Do Conservation Biologists
Use?

• We are improving our ability to assess the
  economic value of ecosystems and their services.
• Industries and government agencies have more
  incentive to preserve ecosystems if monetary
  value is attached to them.

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57.4 What Strategies Do Conservation Biologists
Use?

• Ecosystem Marketplace was launched in 2005 as a
  global clearinghouse for this kind of
  information.
• It is sponsored by environmental groups such as
  the Nature Conservancy and by large corporations
  such as Citigroup.
• Their website offers information on ecosystem
  services and specific information for buyers and
  sellers.

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57.4 What Strategies Do Conservation Biologists
Use?

• The profit value of biodiversity has been
  demonstrated in several instances
• The native vegetation of Western Cape Province,
  South Africa, is a species-rich area called
  fynbos.
• The shrubby vegetation survives droughts, poor
  soils, and frequent fires.
• Two-thirds of Western Capes water comes from the
  fynbos.

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Figure 57.18 Invasive Species Disrupt Ecosystem
Functioning (A)
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57.4 What Strategies Do Conservation Biologists
Use?

• Endemic plants are also harvested for dried
  flowers and thatching, and ecotourists come to
  see the fynbos.
• There are now several exotic species that grow
  faster and taller, increase intensity of fires,
  and transpire a lot of water.
• Stream flows have been decreased by half.

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Figure 57.18 Invasive Species Disrupt Ecosystem
Functioning (B)
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57.4 What Strategies Do Conservation Biologists
Use?

• Removal of the invasives will be very costly
  (140 to 830 per hectare).
• But replacing the services of the fynbos would be
  vastly more expensive.
• A sewage purification plant would cost 135
  million to build and 2.6 million per year to
  maintain (1.8 to 6.7 times more expensive).
• Labor-intensive removal of invasive plants also
  creates jobs.

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57.4 What Strategies Do Conservation Biologists
Use?

• Ecotourism is a major source of income for many
  countries, and it exists because of biodiversity.
• Wild dogs of Africa have been declining due to
  diseases, and ecotourists increasingly want to
  see them.
• A survey showed that ecotourists would be willing
  to pay an extra U.S.12 to see the dogs.

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57.4 What Strategies Do Conservation Biologists
Use?

• This would add up to U.S.90,000 per year for a
  pack of 10 dogs in Kruger National Park in South
  Africa.
• Investigators are now working with other parks,
  lodges, and ranchers to re-establish wild dog
  populations.

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57.4 What Strategies Do Conservation Biologists
Use?

• In Costa Rica, a study was conducted on the
  economic value of pollinators in tropical forests
  adjacent to coffee plantations.
• Coffee production was highest in sites that were
  closest to forest patches.
• Hand-pollination showed that the difference was
  due to the presence of pollinators from the
  forest.

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Figure 57.19 Establishing the Economic Value of
Forest Patches (Part 1)
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Figure 57.19 Establishing the Economic Value of
Forest Patches (Part 2)
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Figure 57.19 Establishing the Economic Value of
Forest Patches (Part 3)
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57.4 What Strategies Do Conservation Biologists
Use?

• The calculated value of pollination for the
  plantation was 60,000 per year, more than
  current conservation incentive payments offered
  to landowners to protect forest.

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57.4 What Strategies Do Conservation Biologists
Use?

• Protected areas alone cannot preserve
  biodiversity even regions where people live can
  also contribute.
• Using these lands in ways that sustain
  biodiversity is known as reconciliation ecology.

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57.4 What Strategies Do Conservation Biologists
Use?

• People are more likely to work to protect local
  interests than on national or global issues.
• The National Wildlife Federation has a program in
  which individuals can have their backyards
  certified as wildlife-friendly.
• Tucson, AZ has initiated a project to make the
  city into important habitat for many species of
  birds.

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57.4 What Strategies Do Conservation Biologists
Use?

• The largest population of bats in North America
  roosts under the Congress Avenue bridge in
  Austin, Texas.
• Their nightly departure to feed is a major
  tourist attraction.
• The bridge was renovated in such a way that the
  expansion joints provide perfect crevices for
  roosting bats.

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57.4 What Strategies Do Conservation Biologists
Use?

• The Turkey Point power plant in southern Florida
  dug a system of canals that cover 6,000 acres for
  cooling the water used in the plant.
• The canals have become home to red mangroves and
  a thriving population of American crocodiles, an
  endangered species. The company now hires
  biologists to monitor the crocodiles and ensure
  their success.

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57.4 What Strategies Do Conservation Biologists
Use?

• Some of the worlds most endangered species are
  held in captivity while threats to their habitats
  are reduced.
• There is not enough space in zoos to maintain
  adequate populations, but captive breeding
  programs have played an important role during
  critical periods.
• These programs also raise public awareness.

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57.4 What Strategies Do Conservation Biologists
Use?

• Captive propagation has helped to save the
  whooping crane and the California condor.
• In 1978, only 2530 condors remained.
• The first chick raised in captivity hatched in
  1988. Six birds were released in 1992. By 2005,
  there were 121 wild condors in California,
  Arizona, and Baja California.

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Figure 57.20 A California Condor Soars
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57.4 What Strategies Do Conservation Biologists
Use?

• The Plimsoll line was a line painted on British
  ships in the nineteenth century to indicate the
  ship was overloaded. It was created by Samuel
  Plimsoll to reduce loss of ships and sailors from
  overloading.
• (Ships were overloaded to increase profits, even
  though it made them unstable and unseaworthy, and
  sink.)

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57.4 What Strategies Do Conservation Biologists
Use?

• We can make an analogy to Earth today the loss
  of species suggests that the load of human
  activities has pushed the hull of Noahs ark
  below the Plimsoll line.
• Science cannot determine an acceptable rate of
  loss. Ethical considerations must figure
  prominently in the decisions that society makes.