Transcript Biodiversity

Part IV. Renewable Resources
A. Fish
B. Forests
C. Water
D. Biodiversity
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D. Biodiversity
Chapter 14
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Introduction
• Extinction of both plant and animal species is occurring at
an unprecedented rate and the result is a decline in the total
variety of life on earth (a loss of biodiversity).
• A species becomes extinct when the last individual
organisms of the species die.
• There are both natural and anthropogenic sources of
extinction.
• The anthropogenic sources are related to market failure.
• The primary question in this chapter is how to provide the
optimal level of biodiversity for an entire ecosystem.
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Natural Extinctions
• Natural extinctions occur when the environment
changes and existing species find themselves at a
competitive disadvantage and are replaced by
existing species that are better adapted to the new
conditions.
• Natural extinctions are always occurring, usually
at a slow pace.
• The disappearance of the dinosaurs is an example
of a massive and rapid extinction, but it actually
took place over a period of about 2 million years. 4
Anthropogenic causes of
species extinction
•
There are several important anthropogenic causes
of extinction:
1. Excessive harvesting of the species
2. Loss of habitat
3. Competition from nonnative species
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Loss of habitat
• Many species are found only in a limited range of
habitat, and if this habitat is destroyed by
conversion into another land use, or contaminated
by pollution, the species will become extinct
• Loss of habitat may be associated with either
open-access or private property resources
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Loss of habitat
• Coral reefs tend to be open-access and are
destroyed both by industrial or fishing-related
pollution
• The owner of a wetland area who is contemplating
converting the wetlands to condominiums makes
the decision by comparing the private net benefits
of conversion with the private net benefits of
preservation.
• Social net benefits are generally excluded.
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Invasives – intentional
• Competition from nonnative species can also be
viewed as an externalities problem.
• Introduction of an exotic species is often
associated with a large ecological and social cost
that is not realized by the person who introduced
the species (intentional introductions of nursery
plants, apple snails)
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Invasives – unintentional
• May arrive as hitchhikers with the importation of
other species, importation of goods, and in the
luggage and on the person of international
travelers.
• A good example of this is the zebra mussel that
has been introduced into the US Great Lakes in
the ballast water of tanker ships.
• Impact native species through direct predation,
competition of ecological resources, or destruction
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of habitat.
Hawaii’s invasive species
?
?
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Open-access harvesting
• Common property resources often have restrictions on
their use while open-access resources do not.
• Cultural traditions of the Native Americans dictated the use
of bison herds and prevented the destruction of the species.
• When Native Americans lost control of their hunting
grounds to nonnative Americans, the buffalo herds became
open-access property, with no restrictions on their use.
• No individual hunter had incentive to preserve the
resource, a destructive race began, with each buffalo
hunter seeking to shoot as many buffalo as possible before
they were shot by competing hunters
• Buffalo quickly disappeared
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Open-access harvesting
• Modern examples: many of the large mammals of
Africa and Asia, such as the elephant, rhinoceros,
tiger, bear, and leopard
• Although hunting of these animals is usually
forbidden by law, it is extremely difficult to
enforce these prohibitions
• High profits associated with illegal trade of
animals makes enforcement extremely difficult.
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Costs of lost biodiversity
• Biodiversity promotes ecosystem stability and
health.
• The more diverse a system the greater its ability to
withstand shocks and stresses.
• In addition, people view a healthy and biodiverse
ecosystem as intrinsically more valuable than a
degraded or less diverse system.
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Costs of lost biodiversity
• Plants and animal species have value because they
may be used to produce economic goods
• Organisms’ genes may be a source of genetic
information that could be used in the development
of new varieties of plants
• A habitat provides an environment in which plants
and animals can exist
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e.g., wetlands
• As an example, wetlands play a unique ecological role as a
transition zone between aquatic ecosystems and terrestrial
ecosystems.
• Wetlands serve as a vast store of nutrients from terrestrial
sources that are gradually released into aquatic systems.
• Most estuarine shellfish and finfish are critically dependent
on the productivity of the wetlands.
• One of the most important roles of wetlands is to serve as a
buffer against storms.
• Wetlands absorb storm water and lessen floods from high
levels of rain.
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Biodiversity policy
• Recognize not only the market value of
biodiversity in areas of medicine and agriculture,
but also the non-market benefits associated with
biodiversity and ecosystem health
• Since future benefits of biodiversity unknown,
precautionary principle should be applied –
biodiversity protected as if the benefits were very
large, even though we cannot prove that they
would be large.
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Minimum viable population
• Another reason to invoke the precautionary
principle in biodiversity has to do with the idea of
a minimum viable population of species
• A population level lower than this minimum
viable level would move the species toward
extinction
• A prudent policy would set the level of population
well above the minimum viable level.
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Minimum viable population
• In some cases, captive breeding programs
have been used to help in the recovery of
species that have fallen below the minimum
viable level.
• In the US, examples of these programs
include the bald eagle and California
condor.
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Policies to reduce loss of habitat
• Loss of habitat is the inevitable result of
economic and population growth
• Excessive loss of habitat occurs when
people confront choices about how to utilize
habitat but do not have an incentive to
incorporate preservation values into their
decision making.
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Policies to reduce loss of habitat
• Consequently, marginal private cost of
converting habitat < marginal social cost
• Closing the disparity between private and
social costs or alternatively, the disparity
between private and social benefits of
preservation is an extremely difficult task.
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Policies to reduce loss of habitat
• Any policy must recognize the public good
characteristics of habitat preservation (nonrivalry
and nonexcludability).
• One approach for addressing the disparity between
private and social benefits from preserving rain
forests would allow the country where the plant,
from which the new medicine is derived, grows to
receive a royalty payment from its use (which
allows the to country share in the benefits from
preservation).
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Policies to reduce loss of habitat
• The implementation of marketable carbon permits
would allow countries to receive positive benefits,
in the form of payments from wealthier countries,
in exchange for preservation of forests.
• This would also address the issue of preserving
carbon sequestration.
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Policies to reduce loss of habitat
• Some issues can be addressed with command and
control regulations
• For example prohibition of wetland destruction
and creation of national parks and wildlife
sanctuaries to protect critical habitat
• The first question that must be answered in the
development of policies to protect habitat is how
much should be protected and at what level of
protection.
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Policies to reduce loss of habitat
• Criteria for developing a prioritization scheme
should consider:
– uniqueness of habitat
– biodiversity contained in the habitat
– importance of habitat for the provision of ecological
services
– existence values associated with the habitat
– the cost of protecting the habitat.
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Endangered Species Act, 1973
• Under this act, it is illegal to use any federal funds in a
fashion that might further threaten endangered species.
• Since federal funds are used in many infrastructure
projects (roads, sewers, etc.) this legislation applies to a
surprisingly large proportion of development projects.
• A major criticism of this act is that it is oriented toward
species in trouble but does nothing directly to protect other
species from becoming endangered or threatened.
• This act came up for reauthorization in 1993, but was not
changed.
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Policies to reduce loss of habitat
•
There are 2 basic types of policies that are
available for protecting and preserving habitat in
general.
1. The creation of protected areas such as national
parks.
2. The restriction of use of privately owned lands. For
example, there are federal and state laws that
restrict the destruction of wetlands.
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Policies to reduce loss of habitat
• In 1991, a controversy developed over the Bush
administration proposal to change the definition of a
wetland from a definition based on soil type and vegetation
to one based on inundation by water for specified times
during the growing season.
• The new definition was not enacted but did serve to point
out the importance of a clear, consistent definition and the
potential for dramatic changes in wetland area designations
should the definition change
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NGOs
• The development of wildlife refuges and nature preserves
is normally thought of as a government activity but is
becoming increasingly private.
• Nongovernmental organizations (NGOs), such as the
Nature Conservancy, can act as agents for individuals.
• These NGOs collect money from individual citizens and
then use the funds to buy critical habitat from private
landowners.
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NGOs
• The private provision of a public good can take
place because of the role of GNOs
• These groups serve to reduce free rider problems
by providing an organization through which
individual citizens can commit to protect habitat
• These organizations also serve to reduce the
transactions costs to citizen action.
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Invasive species policy
• Policies for prevention of introduction of nonnative species are difficult to develop
• The US has a policy of prohibiting importation of
plants and animals believed to be a risk to native
species: “black/red”-listing
• Direct controls can be used to make it illegal to
have undeclared plants and animals in possession
when crossing borders.
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Invasive species policy
• An alternative policy would be to develop a
“white/green list” where people would have to
prove that an imported species is safe before it
could be imported.
• The most promising economic incentive for
addressing non-native species is a liability system
which would make importers liable for future
damages associated with imported plants and
animals.
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Policies to reduce OA exploitation
• The logical solution to open-access exploitation
would be to better define property rights
• However, assignment of private property rights to
wild game and fish would be politically unfeasible
• It is possible to design policies which limit access
such as season limits, limits on the number
harvested, and restrictions on how and where
animals may be harvested.
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Policies to reduce OA exploitation
• However, certain endangered or threatened
animals are not allowed to be harvested at all
• Both assignment of property rights and restriction
of access are ineffectual when profits from illegal
harvesting are high relative to opportunity wage of
the hunter, where the opportunity wage is the
highest alternative wage for the hunter in a
different occupation.
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Policies to reduce OA exploitation
• Policies directed at both supply and demand can
address the open-access issue
• A combination of prohibitions on all sales (supply) of
animal products and publicity campaigns (demand)
making it socially unacceptable to use animal
products can eliminate the profitability of the illegal
trade.
• This was the rationale behind the ban on ivory by the
Convention for International Trade in Endangered 34
Species (CITES).
Summary
• Biodiversity, or the total variety of life on earth, is
important for ecosystem stability, direct and indirect
contributions to social welfare, and the preservation of
genetic information.
• 3 primary anthropogenic sources of loss of biodiversity:
overharvesting, competition from nonnative species, and
loss of habitat.
• Both C&C and economic incentives can be used to
reduce the socially inefficient loss of habitat.
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