REVIEW
Environmental Issues & Problems
ENV 150
What do we mean by “biodiversity”?
Guillaume Mauger
Today: Loss of Biodiversity
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REVIEW
What do we mean by “biodiversity”?
U.S. Office of Technology Assessment:
Biological diversity refers to the variety and
variability among living organisms and their
relative frequency. For biological diversity,
these items are organized at many levels,
ranging from complete ecosystems to the
chemical structures that are the molecular
basis of heredity. Thus, the term
encompasses different ecosystems, species,
genes, and their relative abundance.
What do we mean by “biodiversity”?
More than just diversity of species:
• Diversity of ecosystems
• Diversity of species
• Diversity within a species (genetic)
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Why is biodiversity important?
In other words:
What is the value in biodiversity?
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Valuing Biodiversity
“Ecosystem Services”
• Provisioning services
– Food, water, timber, fiber
• Regulating services
– Regulation of climate, floods, disease, wastes, and
water quality
• Cultural services
– Recreation, aesthetic enjoyment, spiritual
fulfillment
• Supporting services
– Soil formation, photosynthesis, nutrient cycling
source: Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: Biodiversity Synthesis.
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Valuing Biodiversity
Valuing Biodiversity
“Ecosystem Services”
• Provisioning services
• Use values
– Food,values
water, timber,
! Most
are fiber
assigned by humans
• Regulating services
– Regulation of climate, floods, disease, wastes, and
! Most
related to human survival
waterare
quality
• Cultural services
– Recreation, aesthetic enjoyment, spiritual
fulfillment
• Supporting services
– Soil formation, photosynthesis, nutrient cycling
source: Millennium Ecosystem Assessment, 2005. Ecosystems and Human Well-being: Biodiversity Synthesis.
– Direct uses of biodiversity: consumptive - food,
medicines, non-consumptive - eco-tourism
– Subject to trade & commerce, monetary value
readily assigned, varies with demand
• Non-use values
– Indirectly related to humans, ecosystem services,
future options, aesthetics
– Monetary valuation difficult
• Intrinsic value
– Worth ‘in themselves’
source: http://www.jri.org.uk/brief/biodiversity.htm
Valuing Biodiversity
Valuing Biodiversity, examples
Ecotourism worldwide generates from
$950K to $1.8M per minute! e.g.:
•
Kenyan lion, living to age 7:
– $515K in ecotourism, or $1K for its skin
•
Kenyan elephant, living to age 60:
– $1M in ecotourism, or $20-100K for its
tusks
Source: Michael Soulé
Valuing Biodiversity,
examples
Today’s Focus: Species
… How many do we have?
Estimated: 4 to 100 million animal & plant species
Documented: ~1.5M animal, ~400K plant species
Today’s Focus: Species
… How many do we have?
Today’s Focus: Species
… What’s the natural rate of extinction?
Estimated: 5 to 30 million animal & plant species
Documented: ~1.5M animal, ~400K plant species
Source: Millenium Ecosystem Assessment
Today’s Focus: Species
… What’s the natural rate of extinction?
First, definitions:
Local extinction - no longer found in a
specific area (loss of a population)
Ecological extinction - too few to serve
ecological role
Biological extinction - 100% gone.
Today’s Focus: Species
… What’s the natural rate of extinction?
Background extinction rate:
one extinct species per million
species per year: 0.0001% / yr
Today’s Focus: Species
… What’s the natural rate of extinction?
Background extinction rate: one extinct species
per million species per year: 0.0001% / yr
… How is this estimated?
Today’s Focus: Species
… What’s the natural rate of extinction?
Background extinction rate: one extinct species
per million species per year: 0.0001% / yr
… How is this estimated?
Documenting Changes in
Biodiversity
Earth’s History:
“Mass Extinctions”
= catastrophic, widespread event.
= Loss of 25-95% of species within a
relatively short period of time (<5M yrs)
(e.g.: extinction of the dinosaurs)
we’ve had ~5 in the past 500 million years.
The Far Side, G. Larson
Field surveys
Fossil record
Species-area relationships
Mathematical models
Today:
6th mass extinction
Today:
6th mass extinction
“All available evidence points to a sixth
major extinction event currently underway.
Unlike the previous five events, which
were due to natural disasters and
planetary change the current loss of
biodiversity is mainly due to human
activities.”
-UNEP State and Trends of the Environment, 2007
IUCN Red List, definitions
IUCN Red List, example species
(International Union for Conservation of Nature)
The International Union for the Conservation of Nature,
Red List of Threatened Species:
Questions to answer for yourselves:
• About the species & its niche
ENDANGERED (EN)
Considered to be facing a very high risk of extinction
in the wild.
THREATENED / VULNERABLE (VU)
Population does not qualify as Endangered but is
still at risk. Likely to become endangered: risk of
extinction is still high.
– type, habitat, diet, niche, etc.
• Status (i.e., endangered, threatened, etc.)
– How its status was estimated
– Reasons for its current status
– Change in status over time
• Threats
– Past, present, future
source: http://www.iucnredlist.org/
Millenium Ecosystem
Assessment, stats
• “Over half of the 14 biomes that the MA assessed
have experienced a 20-50% conversion to human
use”
• “Across a range of taxonomic groups, the population
size or range (or both) of the majority of species is
declining.”
• “Over the past few hundred years, humans have
increased species extinction rates by as much as
1,000 times background rates that were typical over
the Earth’s history.”
source: http://www.millenniumassessment.org
Millenium Ecosystem
Assessment
Millenium Ecosystem
Assessment, stats
• 16,928 plant and animal species are known to be
threatened with extinction. This may be a gross
underestimate because less than 3% of the world’s
1.9 million described species have been assessed
by the IUCN
• In the last 500 years, human activity is known to
have forced 869 species to extinction
• 1 in 4 mammals and 1 in 8 birds face a high risk of
extinction in the near future
• 1 in 3 amphibians and almost half of all tortoises
and freshwater turtles are threatened.
source: http://www.millenniumassessment.org
What makes a species vulnerable
to threats / extinction?
What makes a species vulnerable
to threats / extinction?
Characteristics of
vulnerable species
•
•
•
•
•
•
•
•
“Big, slow, tasty, or with valuable parts.”
What are the causes of
species decline?
Low reproductive rate
Specialized niche
Narrow distribution
Feeds at high trophic levels
Fixed migratory patterns
Rare
Commercially valuable
Large territories
Direct Causes (“drivers”)
• Habitat change
–
–
–
–
•
•
•
•
•
Land use (e.g., conv. to agriculture)
River modifications
Loss of corals
Sea floor damage (e.g., due to trawling)
By far the
most
important
driver
Invasives
Population and Resource Use
Pollution
Climate Change
Overexploitation
(“HIPPCO”, in book)
Direct Causes (“drivers”)
Habitat loss
Affects:
• 89% of threatened birds
• 83% of threatened mammals
• 91% of threatened plants
• “Island” species (often endemic)
– vulnerable to habitat destruction /
degradation
– e.g.: mountain tops, islands, freshwater
lakes, national parks
• Habitat Fragmentation
– Blocks migration
– Smaller, more vulnerable populations
– Barriers to disperse into new areas,
reproduce, find food
Habitat loss
Invasives
Affects:
• 30% of threatened birds
• 5% of threatened plants
Problem: some have no natural limits to
population growth
– i.e.: no “Environmental Resistance”
Examples:
• 98% of US food supply is from
introduced species
• Zebra mussel
• other examples … ?
Over-exploitation
Pollution
Affects:
• 37% of threatened birds
• 34% of threatened mammals
• 8% of threatened plants
• 8% of threatened reptiles
• Hunting
• Collecting
• Fisheries by-catch
• Trade
Bioaccumulation
– Increasing chemical
concentration in first
organism in a food chain
Biomagnification
ex:
– Increasing chemical
concentration in successive
trophic levels
DDT passed up the food web
Note: not just pesticides! Other pollutants similarly harmful
Millennium Ecosystem Assessment
A few of the Key Messages:
• The benefits of biodiversity go beyond the material, also:
security, resiliency, social, health, freedom of choices and
actions
• The past 50 years have seen the largest changes in
biodiversity in human history
• Although in the past people have benefitted from converting
natural ecosystems to human-dominated ecosystems, these
are resulting in greater and greater costs
• By far the most important cause of biodiversity loss is habitat
change, followed by climate change, invasives,
overexploitation, and pollution.
• In preventing biodiversity loss, short-term trargets are not
sufficient for success: need more holistic approach.
Blue whale
Cause: Whaling
Current moratorium
Millennium Ecosystem Assessment