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Environmental Issues & Problems
ENV 150
Guillaume Mauger
Today: Loss of Biodiversity
What do we mean by “biodiversity”?
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.
REVIEW
What do we mean by “biodiversity”?
More than just diversity of species:
• Diversity of ecosystems
• Diversity of species
• Diversity within a species (genetic)
REVIEW
Why is biodiversity important?
In other words:
What is the value in biodiversity?
REVIEW
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.
REVIEW
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.
! Most values are assigned by humans
! Most are related to human survival
REVIEW
Valuing Biodiversity
• Use values– Direct uses of biodiversity: consumptive - food,
medicines, non-consumptive - eco-tourism
– Subject to trade & commerce, monetary valuereadily 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
REVIEW
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?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?
Today’s Focus: Species
… What’s the natural rate of extinction?
First, definitions:
Local extinction - no longer found in aspecific area (loss of a population)
Ecological extinction - too few to serveecological role
Biological extinction - 100% gone.
Today’s Focus: Species
… What’s the natural rate of extinction?
Background extinction rate:
one extinct species per millionspecies 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?Field surveys
Fossil record
Species-area relationships
Mathematical models
Documenting Changes inBiodiversity
Earth’s History:“Mass Extinctions”
= catastrophic, widespread event.
= Loss of 25-95% of species within arelatively short period of time (<5M yrs)
(e.g.: extinction of the dinosaurs)
we’ve had ~5 in the past 500 million years.
The F
ar
Sid
e, G
. Lars
on
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, definitionsThe International Union for the Conservation of Nature,
Red List of Threatened Species:
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 ofextinction is still high.
source: http://www.iucnredlist.org/
IUCN Red List, example species(International Union for Conservation of Nature)
Questions to answer for yourselves:
• About the species & its niche
– 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
Millenium EcosystemAssessment, stats
source: http://www.millenniumassessment.org
• “Over half of the 14 biomes that the MA assessedhave experienced a 20-50% conversion to humanuse”
• “Across a range of taxonomic groups, the populationsize or range (or both) of the majority of species isdeclining.”
• “Over the past few hundred years, humans haveincreased species extinction rates by as much as1,000 times background rates that were typical overthe Earth’s history.”
Millenium EcosystemAssessment, stats
source: http://www.millenniumassessment.org
• 16,928 plant and animal species are known to bethreatened with extinction. This may be a grossunderestimate because less than 3% of the world’s1.9 million described species have been assessedby the IUCN
• In the last 500 years, human activity is known tohave forced 869 species to extinction
• 1 in 4 mammals and 1 in 8 birds face a high risk ofextinction in the near future
• 1 in 3 amphibians and almost half of all tortoisesand freshwater turtles are threatened.
Millenium EcosystemAssessment What makes a species vulnerable
to threats / extinction?
What makes a species vulnerable
to threats / extinction?
“Big, slow, tasty, or with valuable parts.”
Characteristics ofvulnerable species
• Low reproductive rate
• Specialized niche
• Narrow distribution
• Feeds at high trophic levels
• Fixed migratory patterns
• Rare
• Commercially valuable
• Large territories
What are the causes ofspecies decline?
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)
• Invasives
• Population and Resource Use
• Pollution
• Climate Change
• Overexploitation
By far the
most
important
driver
(“HIPPCO”, in book)
Direct Causes (“drivers”)Habitat loss
• “Island” species (often endemic)– vulnerable to habitat destruction /
degradation
– e.g.: mountain tops, islands, freshwaterlakes, national parks
• Habitat Fragmentation– Blocks migration
– Smaller, more vulnerable populations
– Barriers to disperse into new areas,reproduce, find food
Affects:• 89% of threatened birds• 83% of threatened mammals• 91% of threatened plants
Habitat loss Invasives
Problem: some have no natural limits topopulation growth– i.e.: no “Environmental Resistance”
Examples:
• 98% of US food supply is fromintroduced species
• Zebra mussel
• other examples … ?
Affects:• 30% of threatened birds• 5% of threatened plants
Pollution
Bioaccumulation– Increasing chemical
concentration in firstorganism in a food chain
Biomagnification– Increasing chemical
concentration in successivetrophic levels
DDT passed up the food web
Note: not just pesticides! Other pollutants similarly harmful
Over-exploitationAffects:• 37% of threatened birds• 34% of threatened mammals• 8% of threatened plants• 8% of threatened reptiles
• Hunting• Collecting• Fisheries by-catch• Trade
Blue whaleCause: WhalingCurrent moratorium
ex:
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 andactions
• The past 50 years have seen the largest changes inbiodiversity in human history
• Although in the past people have benefitted from convertingnatural ecosystems to human-dominated ecosystems, theseare resulting in greater and greater costs
• By far the most important cause of biodiversity loss is habitatchange, followed by climate change, invasives,overexploitation, and pollution.
• In preventing biodiversity loss, short-term trargets are notsufficient for success: need more holistic approach.
Millennium Ecosystem Assessment