Download Conservation of Biodiversity

Conservation of Biodiversity
Chapter 40
Conservation biology
• Biodiversity!!
• Emerged in response to a crisis
– At least 10–20% of all species now living most likely will become
extinct in the next 20–50 years
• Bioinformatics
Conservation biology
• Supports following ethical principles:
– Biodiversity is desirable for the biosphere
and, therefore, for humans
– Extinctions, due to human actions, are
undesirable
– Complex interactions in ecosystems
support biodiversity and are desirable
– Biodiversity from evolutionary standpoint
has value in and of itself, regardless of
practical benefit
Biodiversity
• Variety of life on Earth
– Between 10 and 50
million species may
exist
• Extinction
– Of the described
species, nearly 1,200 in
the United States and
40,000 worldwide are in
danger of extinction
• Endangered
species
• Threatened species
Understanding Biodiversity
• Genetic diversity
– variations among the members of a population
• Ecosystem diversity
– dependent on interactions of species at a locale
– Conserve species that play a critical role in an ecosystem
– Saving an entire ecosystem can save many species
• Landscape diversity
– interacting ecosystems within one landscape
– Fragmentation reduces can disrupt seasonal behaviors
• Distribution of Biodiversity
– Biodiversity not evenly distributed throughout the biosphere
– biodiversity hotspots
• contain unusually large concentrations of species
Disrupted ecosystem in Flat-head Lake, Montana
Direct Value of Biodiversity
• Wildlife Has
Medicinal Value
– Most prescription
drugs in the United
States originally
derived from living
organisms
Direct Value of Biodiversity
• Wildlife Has
Agricultural Value
– Crops are derived
from wild plants that
have been modified
– Biological pest controls
are often preferable to
chemical pesticides
Direct Value of Biodiversity
• Wildlife Has
Consumptive Use
Value
– freshwater and marine
harvests depend on the
catching of wild animals
– Provides a variety of
other products that are
sold in the marketplace
worldwide
Indirect Value of Biodiversity
• Biogeochemical Cycles Dispose of Waste
– Biodiversity contributes to workings of water, carbon,
phosphorus, and nitrogen cycles
• Natural Areas Provide Fresh Water, Prevent Soil Erosion, and
Regulate Climate
– Water-holding capacity of forests and wetlands reduces the
possibility of flooding
– Intact ecosystems naturally retain soil and prevent erosion
• Ecotourism Is Enjoyed by Many
– In U.S., people spend $4 billion each year on ecotourism
Wildlife Extinctions
• Habitat loss
• Introduction of alien
species
• Pollution
• Overexploitation
• Disease
1. Habitat loss
• 1,880 threatened and
endangered species in U.S.
• 85% of cases
• Focus on tropical rain forests
and coral reefs
• Loss of habitat also affects
freshwater and marine
biodiversity
– Coastal degradation mainly due
to the large concentration of
people living on or near the coast
– 60% of coral reefs have been or
are on verge of destruction
2. Alien Species
• Nonnative members brought
into new ecosystems through
• Colonization
– Europeans brought various
familiar species with them
when they colonized new
places
• Horticulture and
agriculture
– Aliens have escaped from
cultivated areas
• Accidental transport
– Global trade and travel
• Aliens on Islands
– Islands are particularly
susceptible to
environmental discord
caused by the introduction
of alien species
2. Alien Species
• Everglades National
Park, Florida
–
–
–
–
Pythons
Caiman
Wooly rat
Monitor lizards
3. Pollution
• Environmental change that
damages lives and health
of organisms
• Acid deposition
– sulfur dioxide from power
plants
– nitrogen oxides in
automobile exhaust
– converted to acids when
they combine with water
vapor in the atmosphere
• Eutrophication
– Overenrichment
– algae blooms occur and
upon death, the
decomposers break down
the algae
• in so doing, they use up oxygen
3. Pollution
• Ozone depletion
– Ozone shield absorbs most of the
wavelengths of harmful ultraviolet
(UV) radiation so they do not strike
the Earth
• Organic chemicals
– used in products ranging from
pesticides to dishwashing
detergents, cosmetics, plastics, etc
• Global warming ****
– A 1 meter rise in sea level could
inundate 25–50% of U.S. coastal
wetlands
– Bleaching coral reefs
4. Overexploitation
• Number of individuals taken from a wild
population so great that the population
becomes severely reduced in number
• Positive feedback cycle
– Smaller population
– Greater incentive to capture few
remaining organisms
• Poachers
• Overexploited 11 of 15 major oceanic
fishing areas
– Fish are a renewable resource
– More efficient fishing fleets to
decimate fishing stocks
5. Diseases
• Due to encroachment
of humans on habitat
and other general
interventions
• Pollution can weaken
organisms
– more susceptible to
disease
• May be due to alien
species
– Chytrid fungus
Conservation Techniques
• Habitat Preservation
• Habitat Restoration
Habitat Preservation
• Keystone species
– influence the viability of a
community
– Extinction of a keystone
species can lead to other
extinctions and a loss of
biodiversity
• Metapopulation
– population subdivided into
several small, isolated
populations
– Habitat fragmentation by
humans
• Landscape Preservation
– Landscape protection for
one species is often
beneficial for other wildlife
that share the same space
Habitat Restoration
• Restoration ecology
– Subdiscipline of conservation biology
– Seeks scientific ways to return ecosystems to
former state
– Three principles have so far emerged:
• It is best to begin as soon as possible before remaining
fragments of the original habitat are lost
• Once the natural history is understood, it is best to use
biological techniques that mimic natural processes to
bring about restoration
• Goal is sustainable development, ability of an ecosystem
to maintain itself while providing services to human
beings
Habitat Restoration
•
The Everglades
– Located in southern Florida
– Beginning of 20th century,
settlers began to drain land to
grow crops
– A restoration plan has been
developed that will sustain the
Everglades ecosystem, while
maintaining the services
society requires
– The Everglades is to receive a
more natural flow of water from
Lake Okeechobee
Global Climate Change
• Emissions of
greenhouse gases
are accelerating
• From 2000–2005
global CO2
emissions
increased four
times faster than
in the preceding
10-year span
Climate Change
• In many plants and animals, life cycle events are
triggered by
– Warming temperatures
– Day length
• As global temperatures warm, and day length remains
steady, natural interactions may become out of sync
– Plants may bloom before pollinators have emerged
– Eggs may hatch before dependable food sources are
available
Human Impact on Biomes
• Sustainability
• goal of developing, managing, and conserving Earth’s
resources
• meet the needs of people today without compromising
the ability of future generations to meet their needs
1975
2001
Figure 18.39
The Greenhouse Effect and Global Warming
• Greenhouse gases
–
–
–
–
Include CO2, water vapor, and methane
Are transparent to solar radiation
Absorb or reflect heat
Contribute to increases in global temperatures
Some heat
energy escapes
into space
Sunlight
Atmosphere
Radiant heat
trapped by
greenhouse
gases
Carbon dioxide (CO2) (ppm)
400
350
300
250
0
500
1000
Year
1500
2000
Looking to Our Future
– Emissions of greenhouse gases are accelerating.
– From 2000–2005 global CO2 emissions increased
four times faster than in the preceding 10-year
span.
– In addition, eating locally grown fresh foods may
lower the greenhouse gas emissions that result
from food processing and transportation.
Our future?
• carbon (ecological) footprint
– amount of greenhouse gas emitted as the
result of the actions of a single individual
– reduce our carbon footprints by:
• Reducing our use of energy
• Driving less
• Recycling