Transcript 4.2 Evaluating Biodiversity and Vulnerability ppt.

CONSERVATION AND
BIODIVERSITY
4.2 Evaluating Biodiversity and Vulnerability
Assessment Statements
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4.2.1 Identify factors that lead to loss of diversity.
4.2.2 Discuss the perceived vulnerability of tropical
rainforests and their relative value in contributing to
global biodiversity.
4.2.3 Discuss current estimates of numbers of
species and past and present rates of species
extinction.
4.2.4 Describe and explain the factors that may
make species more or less prone to extinction.
4.2.5 Outline the factors used to determine a
species’ Red List conservation status.
Assessment Statements
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4.2.6 Describe the case histories of three different
species: one that has become extinct, another that is
critically endangered, and a third species whose
conservation status has been improved by
intervention.
4.2.7 Describe the case history of a natural area of
biological significance that is threatened by human
activities.
4.2.1 Identify factors that lead to loss of
diversity.
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Factors that lead to loss of
diversity include:
Natural hazards (volcanoes,
droughts, ice ages, meteor
impacts)
Habitat degradation,
fragmentation, and loss
Agricultural practices
(monoculture, pesticide use, use
of genetically modified
species)
Introduction of non-native
species
Pollution
Hunting, collecting, and
harvesting
4.2.2 Discuss the perceived vulnerability of tropical rainforests
and their relative value in contributing to global biodiversity.
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Tropical rainforests are one of
the two most species-rich and
biodiverse ecosystems on
Earth.
Scientists believe they may
contain half of all species on
Earth, with many existing only
in the canopy, and many not
found anywhere else.
They are under constant threat:
an average of 1.5 hectares
are lost every four second,
which is driven by external
demands for timber, beef, soya
and biofuels.
Valuing them as carbon stores
is helping a little.
4.2.2 Discuss the perceived vulnerability of tropical rainforests
and their relative value in contributing to global biodiversity.
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Rainforests have thinnutrient poor soils, which
means it is difficult for
them to re-grow once
cleared.
Small disturbances
recover fairly quickly,
but large ones do not.
Also if only a limited
amount of timber is
taken it can re-grow
quickly, but too much
means it will not reach
climax community.
4.2.3 Discuss current estimates of numbers of species and past
and present rates of species extinction.
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Five mass extinctions:
Cretaceous-Tertiary 65
m.y.a. – asteroid impact,
16% marine families, 47%
marine genera, 18% land
vertebrate families
End Triassic 200 m.y.a.–
lava erupting, 23% all
families, 48% all genera
Permian-Triassic 250 m.y.a.
– asteroid/comet impact,
95% all species, 53%
marine families, 84%
marine genera, 70% all
land species
4.2.3 Discuss current estimates of numbers of species and past
and present rates of species extinction.
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Late-Devonian 364 m.y.a. –
unknown cause, 19% all
families, 50% all genera.
Ordovician-Silurian 439 m.y.a.
– drop then rise in sea level,
27% all families, 57% all
genera.
m.y.a. – million years ago
Past extinction occurred
suddenly over relatively short
period of time, caused by
environmental catastrophes.
Animals and plants died from
initial event and short-term
environmental turmoil that
followed.
4.2.3 Discuss current estimates of numbers of species and past
and present rates of species extinction.
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Total number of species
currently on Earth is poorly
understood. Current estimates
are between 5 and 100
million, but we have only
identified 1.8 million so far.
Hard to get an accurate count,
because most species not
discovered and described are
very small: insects, bacteria,
and other microbes.
Current mass extinctions are
happening at a faster rate,
which does not give species
time to adapt to changing
conditions. 27,000 species per
year from rainforests.
4.2.4 Describe and explain the factors that may make species
more or less prone to extinction.
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Factors that make animals more
prone to extinction:
Small population size and limited
distribution
Habitat specialists(specific diet or
habitat requirements)
Low reproductive capacity
Poor competitors
Large mammals(ready source of
meat)
Valuable products
Altruistic species(stick together)
Clumping(requires large numbers
for survival)
Position in food chain(Top
predators)
4.2.5 Outline the factors used to determine a species’ Red List
conservation status.
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Factors used to determine
conservation status:
Population size
Reduction in population size
Numbers of mature
individuals
Geographic range and
degree of fragmentation
Quality of habitat
Area of occupancy
Probability of extinction