Download Chap. 2 Global Biodiversity patterns and processes

Threats to biodiversity
(對生物多樣性的威脅)
鄭先祐(Ayo)
國立台南大學 環境與生態學院 院長
[email protected]
Threats to biodiversity
1. Major threats to biodiversity and their
interaction
2. Anthropogenic extinctions and their
community and ecosystem impacts
3. Current patterns of global endangerment
4. What types of species are most vulnerable
to extinction?
5. Responses to the biodiversity crisis
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Fig. 3.1 Major
forces that
threaten
biological
diversity.
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Major threats to biodiversity
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Habitat degradation (棲地的潰敗)
Overexploitation (過度的開發)
Invasive species (入侵物種)
Anthropogenic climate change (人為導致的氣
候變遷)
Bioaccumulation and Synergistic effects(生物
累積和加乘效應)
Snowballing (滾雪球) effect
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bioaccumulation
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p.69 snowballing effects
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Mammalian
megafaunal
genera
(species>44kg)
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Indirect impacts
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Cascade effects (Box. 31.1)
Ecological release
Dominant species
Ecosystem engineers, those species such as
beavers or elephants that strongly modify
habitat.
Keystone species
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Current patterns of global
endangerment

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Table 3.2 number of globally threatened
species by taxon.
Box 3.2 the IUCN red list system.

IUCN = The International Union for the
Conservation of Nature and Natural
Resources.(自然和自然資源的保育)
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p.75 Tab. 3.2
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Box 3.2 The IUCN red list system
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Extinct (Ex):
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A taxon is extinct when there is no reasonable
doubt that the last individual has died.
A taxon is presumed extinct when exhaustive
surveys in known and expected habitat, at
appropriate times (diurnal, seasonal, annual) to
the taxon’s life cycle and life form, throughout its
historic range have failed to record an individual.
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Box 3.2 The IUCN red list system

Extinct in the wild (EW):
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A taxon is extinct in the wild when it is known only
to survive in cultivation, in captivity,
or as a naturalized population well outside the
past range, and there is no reasonable doubt that
the last individual in the wild has dies, as outlined
under EX.
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Box 3.2 The IUCN red list system

Threatened (Table A)
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Near threatened (NT)
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Critically Endangered (CR) (Table A)
Endangered (EN) (Table A)
Vulnerable (VU) (Table A)
A taxon is near threatened when it is likely to
qualify for a threatened category I the near future.
Least Concern (LC)

It is not likely to qualify in the near future.
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Box 3.2 The IUCN red list system

Data deficient (DD)
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A taxon is data deficient when there is inadequate
information to make a direct or indirect
assessment of its risk of extinction based on its
distribution, population status, or both.
Not evaluated (NE)

A taxon in not evaluated if it is has not yet been
evaluated against the criteria.
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Table A overview of criteria (A-E) for
classify species as CR, EN, or VU
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A-1 Reduction in population size (over 10 years or 3
generations in the past where causes are reversible,
understood, and have ceased) >90% >70%
>50%
A-2 Reduction in population size (where causes are
not reversible, not understood, or ongoing) >80%
>50% >30%
B-1 Small range (extent of occurrence) plus any two
of (a) severe fragmentation or few occurrence (CR=1,
EN=2-5, VU=6-10), (b) continuing decline, © extreme
fluctuation. <100 km2 <5000 km2 <20,000 km2
B-2 small range <10 km2 < 500 km2 < 20,000 km2
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Table A overview of criteria (A-E) for
classify species as CR, EN, or VU
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C Small and declining population. (Mature
individuals, plus continuing decline either over a
specific rate in short time periods, or with specific
population structure or extreme fluctuations.) <250
<2500 <10,000
D-1 very small population (mature individuals) <50
<250
<1,000
D-2 very small range (Capable of becoming CR or
EX within a very short time) - - <20 km2 or <5
locations
E Quantitative analysis (estimated extinction risk
using quantitative models, e.g., Population viability
analyses.
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Essay 3.3 An endangered
biological phenomenon
endangered biological phenomenon
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肇致物種危機，不是單純的物種本身的適應能力，而是物種
的生活習性(現象)。
譬如，migrant species
There are two principal reasons why animal
migrations are endangered by human activities
1. Migrant species move through a sequence of ecologically
distinct areas.
2. Aggregation of the migrants can occur, making the animals
especially vulnerable.
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Fig. 3.6 Habitat loss and degradation is the
greatest threat to global diversity among
mammals, birds, amphibians, and gymnosperms.
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Where are species most at risk worldwide?
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Endangered species in the US
Table 3.3 percent of US threaten and endangered
species affected by five types of threat.
 Habitat loss and degradation
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Overexploitation
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27%(M)、69%(B)、37%(R)、27%(A)、53%(F)
Pollution
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45%(M)、33%(B)、66%(R)、17%(A)、13%(F)
Invasive species
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89%(M)、90%(B)、97%(R)、87%(A)、94%(F)
19%(M)、22%(B)、53%(R)、45%(A)、66%(F)
Disease

8%(M)、37%(B)、8%(R)、5%(A)、1%(F)
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Fig. 3.8 Proportion of species threatened with
extinction by plant and animal groups in the US.
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Fig. 3.8 Proportion of species threatened with
extinction by plant and animal groups in the US.
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Freshwater mussels (淡水貝) 70%
Crayfishes(淡水螯蝦) 50%
Stoneflies 43%
Freshwater fishes 38%
Amphibians 37%
Flowering plants 35%
Gymnosperms 25%
Ferns 24%
Tiger beetles, butterflies, skippers, reptiles,
dragonflies 分別約 18%
Mammals 15%
Birds 14%
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Numbers of threatened species in 12 countries
(Table 3.4, p.84)
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Ecuador 2,151 spp.
US 1,143 spp.
Malaysia 892 spp.
Indonesia 833 spp.
China 773 spp.
Mexico 748 spp.
Brazil 697 spp.
Australia 621 spp.
Colombia 593 spp.
India 552 spp.
Madagascar 530 spp.
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Numbers of threatened species in 12 countries
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Fig. 3.9 Contribution of major threats to
endangerment among vertebrate species in China.
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Overexploitation 79%
vertebrate species affected
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Habitat loss 70%
Pollution 20%
Alien species 5%
Disease 1%
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What types of species are most
vulnerable to extinction?
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Specialization
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K-selected life history strategy
Rare species
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Highly restricted geographic range
Seven forms of species rarity, based on three
distributional traits (Table 3.5, p.87)
Population size, geographic range, habitat
specificity.
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“bad luck”: extrinsic causes of
extinction due to human activities

These species are not intrinsically vulnerable
due to their traits but rather have the
misfortune to be in the wrong place, the
wrong time, or of being particularly palatable
to humans.
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Economic and social contexts
of endangerment
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Extreme poverty afflicts over 1 billion people, who
live on less than $1/day, are chronically hungry, lack
clean water and sanitation.
An additional 2.7 billion live on scarcely $2/day, and
are just able to meet their basic needs, but not more.
Globalization spreads the dangers of economic
expansion as countries prioritize international trade
in natural resources to enhance their economies.

This can exacerbate poverty where trade is not tied to
sustainable practices that improve the lives of local people,
but rather provide cheap goods that fuel the economies of
developed nations.
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Responses to the biodiversity crisis
1. Scientific analysis of and communication
about the drivers of change in biodiversity
and human welfare
2. Technological improvements
3. Legal and institutional instruments
4. Economic incentives and plans
5. Social interventions.
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The mechanisms for achieving solutions
1. Establishment of protected (Chap.14)
2. Targeted interventions at genetic, species, and
ecosystem levels that integrate ecological
understanding with community-based problem
solving (Chap.11-13).
3. Restoration of damage ecosystems or
endangered populations(Chap.15)
4. Creation of truly sustainable forms of
development (Chap.16)
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Laws and international agreements that
address biodiversity loss
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Major international agreements, the landmark US
Endangered species Act (ESA), and other key US
laws that protect biodiversity are described in Case
Study 3.3.
Red List index (RLI) tallies changes in status due to
either a deterioration or improvement of all
threatened and near-threatened species since 1988.
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The RLI for birds has decreased by nearly 7% since 1988,
(Fig.3.10, p.91)
Living Planet Index (LPI), summarizes change over
time in populations of over 1100 terrestrial,
freshwater, and marine vertebrate species (Loh, et
al., 2005)

The LPI shows that terrestrial vertebrates have declined by
25% between 1970 and 2000 (Fig. 3.11A)
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Case study 3.1 Enigmatic declines and
disappearances of amphibian populations
1.
2.
3.
4.
5.
6.
Ultraviolet radiation
Disease pathogens
Introduced species
Natural population fluctuations
Climate change
Subtle habitat changes
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Disappearances of amphibian populations
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Case study 3.2 hope for a hotspot: preventing an
extinction crisis in Madagascar
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Madagascar as a biodiversity hotspot
Hotspot under siege (侵襲)
Promise for protected area expansion
Maximizing protected area design for biodiversity
conservation
From planning to park establishment: the case of
Masoala
Continuing the legacy(遺產): sustainability and
financing of a new reserve system
Protected areas: providing promise for Madagascar
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Case study 3.3 Key international and US
Laws
Biodiversity
 The convention on international trade in
endangered species of wild fauna and flora.
(CITES), first opened for signature in 1973.
 Convention on biological diversity (CBD) was
opened for signature in 1992 at the Earth
Summit in Rio de Janeiro, and now includes
188 countries as parties (but not the US).
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Habitat and ecosystem
protections
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The United Nations’ Educational, Social and
Cultural Organization’s (UNESCO) Man and
the Biosphere Programme provides an
intitutional unbrella for a series of
international Biosphere Reserves.
The Convention on Wetlands, also known as
the Ramsar convention after the city in Iran
where it was originally signed in 1971.
The UN Environment Program’s Regional
Seas initiative.
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美國 Federal laws
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Endangered species Act
National Forest Management Act
The Magnusun Act
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The Magnusun Fishery conservation and
management Act of 1976 (amended substantially
in 1996) controls marine resourcesm particularly
commercially valuable fish species, within the US
Exclusive economic zone, the area within 200
nautical miles of the country’s coastline.
Marine Mammal Protection Act
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Questions for discussion
1. Despite considerable efforts, we know very little
about the status of most of the world’s species.
How can we improve our knowledge on species
endangerment? What kinds of information might be
most helpful to garner, and why?
2. In two or three decades’ time, your children or other
youngsters may ask you a question along the lines
of “when the biodiversity crisis became apparent in
its full scope during the 1990s, what did you do
about it?” What will your answer be?
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問題與討論
http://mail.nutn.edu.tw/~hycheng/
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