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Evaluating Biodiversity & Vulnerability
IB Syllabus: 4.2.1 – 4.2.7
AP syllabus
Ch.22, 23, 24
Planet in Peril – episode 1
Syllabus Statements
• 4.2.1: Identify factors that lead to a loss of diversity• 4.2.2: Describe 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
• 4.2.6: Describe the case histories of three species: one that has become extinct, another that is currently endangered, and a third 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
How is biodiversity lost?
• Natural Processes– Natural hazards (volcanoes, drought, mudslide)– Global catastrophies (ice age, meteor impact)
• Human Processes– Habitat degradation, fragmentation & loss– Introduction/escape of nonnative species,
genetically modified organisms, monoculture– Pollution– Hunting, collecting, harvesting. overfishing
Rain Forests – A Case Study
• 2% of the land surface with 50-80% of the terrestrial species
• Characterized by warm constant temperature, high humidity & rainfall
• Vertical stratification provides niche diversification
• Decomposition rates are extremely fast little litter, thin nutrient poor soil
• Nutrients stored in biomass of organisms
The threats to rainforests
• Most of destruction since 1950
• Brazil has ½ remaining world rainforest
• At current rates of deforestation Brazil’s rainforest will be gone in 40-50 years
• Total loss yearly to deforestation is 50,000 to 170,000 km2
• 1.5 ACRES LOST PER SECOND worldwide
• Cutting & degradation at even faster rates
• Highest average annual deforestation of primary forests, 2000-2005, by area. All countries
1 Brazil -3,466,000 • 2 Indonesia -1,447,800 • 3 Russian Federation -532,200 • 4 Mexico -395,000 • 5 Papua New Guinea -250,200 • 6 Peru -224,600 • 7 United States of America -215,200 • 8 Bolivia -135,200 • 9 Sudan -117,807 • 10 Nigeria -82,000
Amazon Rainforest• The Amazonian Rainforest covers over a billion acres, encompassing areas
in Brazil, Venezuela, Columbia and the Eastern Andean region of Ecuador and Peru.
• If Amazonia were a country, it would be the ninth largest in the world. • The Amazon Rainforest has been described as the "Lungs of our Planet"
because it provides the essential environmental world service of continuously recyling carbon dioxide into oxygen.
• More than 20 percent of the world oxygen is produced in the Amazon Rainforest.
• More than half of the world's estimated 10 million species of plants, animals and insects live in the tropical rainforests. One-fifth of the world's fresh water is in the Amazon Basin.
• One hectare (2.47 acres) may contain over 750 types of trees and 1500 species of higher plants.
Amazon effects
• 1/3 of rainforest destruction from shifting cultivation• Rest cleared for pasture- then planted with African
grasses for cattle• When pasture price exceeds forest prices incentive
for land clearing• Government subsidized agriculture and colonization• Improved infrastructure for transport• In Brazil alone, European colonists have destroyed
more than 90 indigenous tribes since the 1900's.
Plants uniquely adapted to the conditions there
Why rainforests vulnerable
Ecology• Pollinator relationships – reproduction
depends on other organisms• Poor, thin soils – easily eroded once trees
removed, little chance for regrowthLocation
• Surrounded by rapid population growth of developing countries – pollution, waste, space
• Poor economy benefits from any resources that are harvestable
• Economic – raw materials, exports, cattle, oil & gas
• Socio-political – Pressures of population growth, subsidize tree plantations, colonization
• Ecological – Invasive species, climate change, soil degradation
General Pressures on Rainforests
BromeliadBromeliad
OrchidOrchid
RoadsRoadsLoggingLogging
Cash cropsCash crops
Cattle ranchingCattle ranching
Tree plantationsTree plantations
Flooding from damsFlooding from dams
MiningMining
Oil drillingOil drilling
Unsustainable peasant farmingUnsustainable peasant farming
Primary Causes:Primary Causes:
Rapid population growthRapid population growth
Exploitive government policiesExploitive government policiesPovertyPoverty
Exports to developed countiesExports to developed counties
Failure to include ecological servicesFailure to include ecological servicesin evaluating forest resourcesin evaluating forest resources
ToucanToucan ScarletScarletmacawmacaw
Golden lionGolden lionmarmosetmarmoset
Blue morpho butterflyBlue morpho butterfly
Secondary Causes:Secondary Causes:
Interconnected Causes Of Degradation &
Destruction of TropicalRainforests
Revolve around1. Population
Growth2. Poverty3. Government
Policy
Rodonia Brazil: Acquired by the Advance Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on August 24, 2000, the false-color image combines near-infrared, red, and green light. Tropical rainforest appears bright red, while pale red and brown areas represent cleared land. Black and gray areas have probably been recently burned. The Jiparaná River appears blue.
Secondary results
• Clearing rainforests degrades tropical rivers– Water more turbid, silts river bottoms, nutrient
overload in estuaries, smothers offshore coral reefs
• Accelerates flooding & reduces aquifer recharge
• Affect precipitation patterns– Flow of moisture to downwind areas is reduced
Why are they special? Or…
• Why should we care?• Some biogeographers claim that loss of
tropical rainforests is no more important than loss of old growth forests in EU & NA
• 1. Important ecological & environmental services
• 2. Instrumental values medicines from plants
• 3. Cultural value
Instrumental Values of Tropical Forest Ecosystems
Use Values Nonuse Values
Direct Use Values Indirect UseValues
Option Values Existence Values
Timber and otherbuilding materials
Fuelwood
Medicinal plants
Edible wild fruitsand plants
Fiber
Soil fertility
Flood control
Water purification
Pollution control
Recreation andtourism
Education
Ecologicalservices (pestcontrol,pollination)
Geneticinformation
Future products:
Medicines
Geneticresources
Biologicalinsights
Food sources
Buildingsupplies
Future ecologicalservices
Protection ofbiologicaldiversity
Maintainingcultures of localpeople
Continuingecological andevolutionaryprocesses
Cultural Extinction• 250 million people in 70 countries from
indigenous rainforest cultures• Hunting & Gathering, Sustainable Agriculture• Remaining tribal people are disappearing with
their lands• Irreplacable loss of ecological & cultural
knowledge – most medicine men 70+ years old• Need protection & ownership of land to survive• BUT that stands in the way of progress
The HuliPapua New Guniea
The Yanomami South America
The PygmiesCentral Africa
Prevention Restoration
Protect most diverse andendangered areas
Educate settlers about sustainableagriculture and forestry
Phase out subsidies that encourageunsustainable forest use
Add subsidies that encouragesustainable forest use
Protect forests with debt-for-natureswaps, conservation easements,and conservation concessions
Certify sustainably grown timber
Reduce illegal cutting
Reduce poverty
Slow population growth
Reforestation
Rehabilitationof degradedareas
Concentratefarming andranching onalready-clearedareas
Biodiversity will decrease from…
1. Environmental Stress
2. Large environmental disturbance
3. Extreme environmental conditions
4. Severe limitation of an essential nutrient, habitat, or other resource
5. Introduction of a nonnative species
6. Geographic isolation
Food supply and demand
Freshwatersupply and
demand
Forest productsupply and
demandClimate change
Biodiversity loss
Habitatchange
Changes intranspirationand albedo Loss
of cropgenetic
diversity Reducedresistanceto change
Loss andfragmentation
of habitat
CO2 emission
Habitat changeand fragmentation
of habitat
Changes inprecipitation
and temperature
Water availability
Water use and pollutionand soil nutrient loss
CO2, CH4,
N2O emissions
Erosion,pollution, and
changes inwater flow
Loss and fragmentation
of habitat
Loss and fragmentation
of habitat
DeforestationDeforestationChanges inwater supply and
temperature
Changes inwater supply and
temperature
About 1.5 - 10 million Species live on Earth
Estimates of the Numbers of Species in the World
Source: World Conservation Monitoring Centre, Global Biodiversity - Status of the Earth's Living Resources, 1992.
Groups of Organisms Species described
Maximum estimates
Most conservative estimates
Viruses 5,000 500,000 500,000
Bacteria 4,000 3,000,000 400,000
Fungi 70,000 1,500,000 1,000,000
Algae 40,000 10,000,000 200,000
Plants 250,000 500,000 300,000
Vertebrates 45,000 50,000 50,000
Nematodes 15,000 1,000,000 500,000
Molluscs 70,000 180,000 200,000
Crustaceans 40,000 150,000 200,000
Arachnids 75,000 1,000,000 750,000
Insects 950,000 100,000,000 8,000,000
18000 to 50000 species lost per year1 species lost every 20 minutesEstimates differ but over 50 species lost per day is probably accurateStop the Clock – www.conservation.org/act
67%Secure orapparently
secure
1%Other
16%Vulnerable
8%Imperiled
7%Critically imperiled
1% Probably extinct
Current Classification of Species
How can we reduce biodiversity loss?
• 2 main approaches – ecosystem or species directed
1. Preventing premature extinction of species
2. Preserving & restoring ecosystems which provide habitats and resources for the world’s species
The Species Approach The Ecosystem Approach
Goal
Protect species frompremature extinction
Strategies
• Identify endangered species
• Protect their critical habitats
Tactics
• Legally protect endangered species
• Manage habitat
• Propagate endangered species in captivity
• Reintroduce species into suitable habitats
Goal
Protect populations ofspecies in their naturalhabitats
Strategy
Preserve sufficient areasof habitats in differentbiomes and aquaticsystems
Tactics
• Protect habitat areas through private purchase or government action
• Eliminate or reduce populations of alien species from protected areas
• Manage protected areas to sustain native species
• Restore degraded ecosystems
Endangered vs. Threatened
• Organisms are classified for conservation purposes Traditionally into 2 groups
1. Endangered• So few individuals that it could become extinct
over all of its natural range• Without protection critically endangered
extinct
2. Threatened• Still abundant in range but declining numbers• Ecological warning signs
Red Data Books
• List the species in the red – the ones most in jeopardy of extinction
• Various factors contribute to identifying species as threatened, of concern, endangered, extinct
• Examples - population size, reduction of population size, numbers of mature individuals, geographic range and degree of fragmentation, quality of habitat, area of occupancy, probability of extinction
• http://www.iucnredlist.org/
Figure 22-7 (1)Page 564
Florida manatee
Northern spotted owl (threatened)
Gray wolf Florida panther Bannerman's turaco (Africa)
Devil's hole pupfish
Snow leopard(Central Asia)
Black-footed ferret
Symphonia(Madagascar)
Utah prairie dog(threatened)
Ghost bat(Australia)
California condor
Black lace cactus
Black rhinoceros(Africa)
Oahu tree snail
Figure 22-7 (2)Page 565
Grizzly bear(threatened)
Arabian oryx(Middle East)
White top pitcher plant
Kirtland's warbler
African elephant(Africa)
Mojave desert tortoise (threatened)
Swallowtail butterfly
Humpback chub
Golden lion tamarin (Brazil)
Siberian tiger(Siberia)
Figure 22-7 (3)Page 565
West Virginiaspring salamander
Giant panda(China)
Knowlton cactus
Mountain gorilla(Africa)
Swamp pink
Pine barrens tree frog (male)
Hawksbill sea turtle
El Segundo blue butterfly
Whooping crane
Blue whale
EXTINCTION
Evidence from the past
• The fossil record remains first and foremost among the databases that document changes in past life on Earth.
• The fossil record clearly shows changes in life through almost any sequence of sedimentary rock layers.
• Successive rock layers contain different groups or assemblages of fossil species.
3 Types of Extinction
1. Local extinction (extirpation) species no longer found in an area where it was once found
• Still found elsewhere (= population extinction)
2. Ecological extinction so few members of a species are left that it can no longer play its ecological role in the ecosystem
3. Biological extinction species is no longer found anywhere on the earth
Mass Extinctions Epoch Cause Species Lost
Precambrian Glaciation Stromatolites
Cambrian O2 Depletion Olnellids
Ordovician Glaciation of Gondwana
Brachiopods
Devonian Meteor, Glaciation Early corals
Permian Pangea Trilobites
End Cretaceous Meteor, Volcanoes Dinosaurs
Holocene Humans All forms
Permian mass Extinction
- Permian Period (286-248 million years ago) Formation Of Pangea
- Terrestrial faunal diversification occurred in the Permian
- 90-95% of marine species became extinct in the Permian (largest extinction in history)
- Causes? = Formation of Pangea reduced continental shelf area, glaciation, Volcanic eruptions
The End-Cretaceous (K-T) Extinction
- Numerous evolutionary radiations occurred during the Cretaceous (144-65 million years ago) 1st appearance of dinosaurs, mammals, birds, angiosperms
- A major extinction occurred at the end of the period- 85% of all species died in the End-Cretaceous (K-T) extinction (2nd largest in history)
- Causes? = Meteor impact in the Yucatan, Volcanic eruption both supported geolocially, cause climate change, atmospheric changes
Extinction Rates• Biologists estimate that 99.9% of all species ever in
existence are now extinct– Background extinction – local environmental changes
cause species to disappear at low rate– mass extinction – catastrophic, widespread (25 – 75%
of existing species– mass depletion – higher than background but not mass
• Cause temporary biodiversity reductions but create vacant niches for new species to evolve
• 5 million years of adaptive radiation to rebuild diversity after extinction
Premature extinction from human causes
Passenger pigeon
Great auk Dodo Dusky seaside sparrow
Aepyornis(Madagascar)
Main factors Overhunting, Habitat Destruction &Introduction of Exotic Species
Differences in Cause of Extinction
Historically most mass extinctions were caused by
• Catastrophic Agents- such as meteorite impacts and comet showers,
• Earth Agents- such as volcanism, glaciation, variations in sea level, global climatic changes, and changes in ocean levels of oxygen or salinity
Currently a mass extinction is being caused by the actions of 1 species Us
Which species are most vulnerable?
• Vulnerability of species affected by …– Numbers – low numbers = automatic risk– Degree of specialization = generalists adapt better
than specialists– Distribution = widely distributed organisms, may
migrate out of harms way & different effects by area– Reproductive potential – if low = vulnerable– Reproductive behaviors – how complex, picky, …– Trophic level – higher are more vulnerable to
biomagnification & trophic cascades
Characteristic Examples
Low reproductive rate(K-strategist)
Specialized niche
Narrow distribution
Feeds at high trophic level
Fixed migratory patterns
Rare
Commercially valuable
Large territories
Blue whale, giant panda,rhinoceros
Blue whale, giant panda,Everglades kite
Many island species,elephant seal, desert pupfish
Bengal tiger, bald eagle,grizzly bear
Blue whale, whooping crane,sea turtles
Many island species,African violet, some orchids
Snow leopard, tiger, elephant, rhinoceros, rare plants and birds
California condor, grizzly bear, Florida panther
Indian Tiger
Range 100 years ago
Range today(about 2,300 left)
Black Rhino
Range in 1700
Range today(about 2,400 left)
African Elephant
Probable range 1600
Range today(300,000 left)
Asian or Indian Elephant
Former range
Range today(34,000–54,000 left)
Vulnerability of ecosystems
1. Diversity at species, genetic, ecological or functional levels
** Remember, Diversity = Stability **
2. Resilience Ability of a living system to restore itself to original condition after being exposed to a minor outside disturbance
3. Inertia ability of a living system to resist being disturbed or altered
Biome % of Area Disturbed
Temperate broadleaf forests
Temperate evergreen forests
Temperate grasslands
Mixed mountain systems
Tropical dry forests
Subtropical and temperate rain forests
Cold deserts and semideserts
Mixed island systems
Warm deserts and semideserts
Tropical humid forests
Tropical grasslands
Temperate boreal forests
Tundra
94%
94%
72%
71%
70%
67%
55%
53%
44%
37%
26%
18%
0.7%
Leading causes of wildlife depletion & extinction
1. Habitat loss, fragmentation or degradation
• Agriculture, urban development, pollution• Prevent dispersal, mating, gene flow
2. Deliberate or accidental introduction of non-native species
• Rapid reproduction, no competitors, no predators, upset energy flow
Overfishing
Habitatloss
Habitatdegradation
Introducingnonnativespecies
Commercialhunting
andpoaching
Sale ofexotic pets
anddecorative
plants
Predatorand
pest control
Pollution
Climatechange
Basic Causes
• Population growth• Rising resource use• No environmental
accounting• Poverty
Case Studies - Elephants
Endangered 1. Ecological pressures – shrinking habitat2. Socio-political pressures – recovery of
elephants in smaller habitats = widespread habitat destruction, other species now poached for ivory
3. Economic pressures – poaching for ivory
• Ecological Role – keystone species, maintains grassland community by removing trees
• Consequences – loss of ecosystem type
Case Studies – Passenger Pigeon
Extinct September 1, 1914 1. Ecological pressures – clearing virgin forests for
agriculture lost food & nests, 1 egg laid per year2. Socio-political pressures – Supply meat for
growing east coast cities3. Economic pressures – easy capture in large
dense flocks, roosts markets in the east
• Ecological Role – once most numerous bird on the planet
• Consequences – linked to spread of lyme disease
Case Studies – American Alligator
Recovered June 4 19871. Ecological pressures – shrinking habitat2. Socio-political pressures – alligator nuisance,
sustainable use, tourism3. Economic pressures – confused with American
Crocadile hunted for skins
• Ecological Role – keystone predator, gator holes in everglades, top carnivore
• Consequences – loss of fish & bird populations & change whole everglades ecosystem structure / now healthy systems
Alligator mississippiensis
Remember
• That current changes in species numbers will be exacerbated by global warming
When is endangered really “in danger”
• Is there a number where the population is too small to survive?
• MVP = minimum viable population the smallest number of individuals necessary to ensure the survival of a population in a region for a specified timer period
• Time range typically 10-100 years• Most indications are that a few thousand
individuals is the MVP if time span is > 10 years
Genetic Bottlenecks
• If populations recover from times with small numbers other problems can persist
• Genetic bottlenecks• Think of a traffic bottleneck many cars
approach and stop, only a few get through.• Same with genes – genetic diversity is
dramatically reduced• When populations are reduced to small
numbers interbreeding occurs and genetic diversity plummets
Cheetahs• A few thousand years ago cheetahs
experienced a population crash• They have since recovered but they are
almost all genetically identical• Why is this a problem?
1. Inbreeding increased the chances of deformity from recessively inherited diseases
2. Identical genes gives identical vulnerability to disease
3. Weakened physiology – exaggerated recovery time from activity makes them vulnerable
References
• www.rainforestweb.org
• www.redlist.org