review environmental issues & problems env 150...

Environmental Issues & Problems

ENV 150

Guillaume Mauger

Today: Loss of Biodiversity

What do we mean by “biodiversity”?

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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.

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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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“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

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• 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

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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


… How many do we have?Estimated: 5 to 30 million animal & plant species

Documented: ~1.5M animal, ~400K plant species

Source: Millenium Ecosystem Assessment


… 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.



Background extinction rate:

one extinct species per millionspecies per year: 0.0001% / yr


… 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?


… 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

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