Download Value and Maintenance of Biodiversity

Value and Maintenance of
Biodiversity
Biology/Env S 204
Spring 2009
Value and Maintenance
• Benefits to humans, direct or indirect
• Intrinsic value
• What kind of a world do we want to
live in?
• Redundancy in ecosystems (how much
is enough?)
Benefits to humans
• Direct use value = marketable
commodities
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Food
Medicine
Raw materials
Recreational harvesting
Ecotourism
Benefits to humans: food
• About 3,000 species (ca. 1% of
300,000 total) of flowering plants
have been used for food
• About 200 species have been
domesticated
• Wild relatives source of genes for
crop improvement in both plants and
animals
Benefits to humans: medicine
• Organisms as chemists
• About 25% of all medical prescriptions
in the U.S. are based on plant or
microbial products or on derivatives or
on synthetic versions
• Some medicinal products from animals
(e.g., anticoagulant from leeches)
Benefits to humans: raw
materials
• Industrial materials:
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Timber
Fibers
Resins, gums
Perfumes
Adhesives
Dyes
Oils, waxes, rubber
Agricultural chemicals
Benefits to humans:
recreational harvesting
• Recreational harvesting:
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Hunting
Fishing
Pets
Ornamental
plants
Benefits to humans: ecotourism
• By definition based on biodiversity
• Growing portion of the tourism
industry
Indirect Use Value
• Indirect use value = services provided
by biodiversity that are not normally
given a market value (often regarded
as free)
• Include primarily ecosystem services:
atmospheric, climatic and hydrological
regulation; photosynthesis; nutrient
cycling; pollination; pest control; soil
formation and maintenance, etc.
Indirect Use Value
• Biosphere 2 was an attempt to
artificially create an ecosystem that
would sustain human life
• Ca. US$200 million invested in design
and construction plus millions more in
operating costs
• Could not sustain 8 humans for two
years
Intrinsic value
• Simply because it exists
• Moral imperative to be good stewards,
the preservation of other life for its
own sake
• Supported in many different religious
or cultural traditions
• Recognized in the Convention on
Biodiversity
Intrinsic Value
• Biophilia = the connection that human
beings subconsciously seek with the
rest of life (nature) or the innate
connection of humans to biodiversity
Intrinsic Value
• Biophilia = the connection that human
beings subconsciously seek with the
rest of life (nature) or the innate
connection of humans to biodiversity
• Should we put a monetary value on
everything?
Intrinsic Value
• Biophilia = the connection that human
beings subconsciously seek with the
rest of life (nature) or the innate
connection of humans to biodiversity
• Should we put a monetary value on
everything?
• If something can be valued, it can be
devalued.
What kind of a world do we
want to live in?
• Human co-opt about 40% of the
net primary productivity on an
annual basis
• Human population at over 6 billion
and growing at about 80 million
per year
• Loss of some biodiversity is
inevitable
What kind of a world do we
want to live in?
• Current extinction rate much higher than
background; also commitment to extinction
• Extinction is forever; species may have
unforeseen uses or values (e.g., keystone
species, medicinal value, etc.)
• Biodiversity has recovered after previous
mass extinctions, but are we also
eliminating that possibility by severely
restricting conditions conducive to
evolution?
What kind of a world do we
want to live in?
If 6 billion people consume 40% of
the annual net primary productivity,
what is the theoretical limit (=
carrying capacity) for humans under
current conditions?
2.5 x 6 billion = 15 billion
What kind of a world do we
want to live in?
But this number does not factor in the
costs of dealing with wastes or nonrenewable resources.
Nor does it leave room for other
biodiversity, upon which we depend
for ecosystem services (such as waste
removal/recycling).
Human population is expected to reach
ca. 12 billion by 2050.
What kind of a world do we
want to live in?
• This is why many now argue that we
have to find a way to put biodiversity
into the economic equation
• Previously no monetary values were
associated with natural resources
except the actual ones generated by
extraction (the world is there for us
to use)
What kind of a world do we
want to live in?
• Extraction costs (e.g., labor, energy)
usually computed
• But cost of replacement not included,
nor costs of the loss of the services
provided by that resource or its
ecosystem (e.g., cutting forest for
timber)
• Because costs are undervalued,
benefits of extraction are overvalued
What kind of a world do we
want to live in?
• Green accounting proposed as part of
the solution
• But requires that environmental assets
have proper prices (p. 171,
Chichilnisky essay in text)
• Tie in to property rights for natural
resources
Redundancy in Ecosystems
• Or, how much biodiversity is
enough?
• How much redundancy is built into
ecological processes/communities?
• To what extent do patterns of
diversity determine the behavior
of ecological systems?
Redundancy in Ecosystems
Two opposing views: rivet
hypothesis vs. redundancy
hypothesis
rivet
redundancy
Redundancy in Ecosystems
• Rivet hypothesis: most if not all
species contribute to the integrity of
the biosphere in some way
• Analogy to rivets in an aircraft—there
is a limit to how many can be removed
before the structure collapses
• Progressive loss of species steadily
damages ecosystem function
Redundancy in Ecosystems
• Redundancy hypothesis: species
richness is irrelevant; only the
biomass of primary producers,
consumers and decomposers is
important
• Life support systems of the planet
and ecological processes will generally
work fine with relatively few species
Redundancy in Ecosystems
• In the past (from fossils), most
ecological systems have been
conspicuously less species rich
• But no evidence that they operated
any differently
Redundancy in Ecosystems
• Major patterns of energy flow and
distribution of biomass in existing ecological
systems may be broadly insensitive to
species numbers
• But systems with higher diversity and more
kinds of interactions may be more buffered
from fluctuations
• Lack of data regarding the link between
species-richness and ecosystem function
Redundancy in Ecosystems
• Middle ground: ecosystem processes
often but not always have
considerable redundancy built into
them
– Not all species are equal (e.g., functional
groups, keystone species)
– The loss of some species is more
important than the loss of others
– Species loss may be tolerated up to some
critical threshold