© 2011 Pearson Education, Inc. Value of wild species & biodiversity Ecosystem capital: goods &...

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Value of wild species & biodiversity

• Ecosystem capital: goods & services provided to humans by natural systems

• ecosystem capital = ecosystems• ecosystems = wild species

• Ecosystem sustainability = save ecosystem integrity, resilience, processes, biodiversity

Biological wealth• 2 million species examined, named, classified• 5–30 million species

• Biota: natural species of living things

• Biological wealth: biota + their ecosystems• = ecosystem capital & sustains humans• major part of a country’s total wealth

• Biodiversity: variety of living species

Biodiversity Value• Why shouldn’t we hunt species to extinction?

• Wild species have value & essential to preserve

• By identifying this value we can assess our moral duties to species

• Instrumental value: a species’ existence benefits some other organism• Food, shelter, source of income• Usually anthropocentric

• preserve species = enjoy benefits provided

• Intrinsic value: value for own sake• not have to be useful to us• Do animals have rights? Or are they simply property?

• Many believe only humans have intrinsic value• no reason to preserve “insignificant” species

Recreational, aesthetic, and scientific uses

• Ecotourism: tourists visit a place to observe wild species or unique ecological sites• It is the largest foreign exchange-generating

enterprise for many developing countries

• Environmental degradation affects commercial interests

Biodiversity & its decline

• Biodiversity = genetic diversity too

• Species #•How “even” the species are

• ↓biodiversity if dominated by 1 species with few other species

• ↑biodiversity if dominance of any 1 species ↓

• Endemic species- found in 1 habitat• at risk

• North America still not well-known• At least 500 species (100 vertebrates) extinct• 1/3 species are vulnerable or extinct

North America• Freshwater habitats ↑ risk• Ex: Mussels, crayfish, fishes, amphibians• American SE ↑ freshwater diversity

• Declining• Fish, amphibians, songbirds• More than 25% of North American birds are

declining

The state of U.S. species

Global outlook

• The global loss of biodiversity is disturbing• The background (past) extinction rate is less than

one extinction every thousand years for mammals• Except for the five great extinction events

• Current extinction rate = 100–1,000 times greater than past rates• For mammals and birds = 20–25 species per 100

years• Rates for all groups = 850 species over 500 years• 23% of mammal species and 12% of bird species

are threatened

Species extinction rates

Most threatened species are in the tropics• The tropics have almost unimaginable biodiversity• 43 species of ants occur on one tree in Peru• Equal to all ant fauna of the British Isles

• 300 species of trees on a 1-ha (2.5-acre) plot• 1,000 species of beetles on one tree species in

Panama

• Tropical forests are also experiencing the highest rate of deforestation• The species inventory is so incomplete it’s almost

impossible to assess extinction rates

Reasons for the decline• HIPPO• Habitat destruction• Invasive species• Pollution• Population• Overexploitation

Biodiversity loss in the developing world• developing world• Biodiversity is greatest• So is human population growth

• Asia & Africa have lost two-thirds of their original natural habitat• People’s desire for a better life• Desperate poverty• Global market for timber and other resources

The border of Haiti and the Dominican Republic

Habitat change: fragmentation• mosaic of different land uses• contrast with neighboring patches

• Fragmentation small # & species populations • Species vulnerable to extinction

Fragmentation

Fragmentation: edge• Reducing habitat size increases edge• Exposing species to predators and nest parasites

• Edge is beneficial to some species but not to others• Kirtland’s warbler, an endangered species, depends

on jack pines in Michigan• Forests have been fragmented, creating edge• Brown-headed cowbirds are nest parasites that lay

their eggs in the warbler’s nest• Edge also favors nest predators (crows, magpies, jays)

Habitat change: simplification and intrusion• Simplification: humans simplify habitats• Removing logs and trees changes forest

microhabitats• Streams are channelized (straightened), reducing

fish and invertebrate species

• Intrusion: human structures• Millions of migrating birds crash into

telecommunication towers• Cell phone tower lights affect birds migrating at night• Up to a billion birds die each year by crashing into

windows

Invasive species• An exotic (alien) species: one that is introduced into

an area from somewhere else• Most don’t survive or don’t become pests• Invasive species: thrives, spreads, and can eliminate

native species by predation or competition

• Accidental introductions: the brown tree snake • Entered Guam on cargo ships• Within 50 years, it eliminated 9 of 12 bird species• It has no natural enemies• Wildlife officials are trying to prevent its spread

The brown tree snake

• Aquaculture: the farming of shellfish, seaweed, and fish• Introducing parasites, seaweeds, invertebrates,

pathogens• Species escape and enter nearby waterways

The Brazilian pepper bush

Invasive species and trophic levels• Nonnative plants have different resistance

mechanisms• Make it harder for herbivores to eat• Energy and materials may not pass up the food

• Norway maples were introduced to North America in 1756• They provide less food up the food chain for

herbivores (caterpillars) and their predators (song birds)

Population• Human populations put pressure on species• Direct use, habitat conversion, pollution

• Large numbers of humans use resources wild species need• Even if each person uses small amounts of resources

• A small group of people can overuse resources• People with highly consumptive resources have a

disproportionate effect on the environment

• Different levels of consumption and numbers of people drive tensions between countries

Overexploitation: trade in exotics• Overexploitation: overharvest of a particular species• Removing individuals faster than they can reproduce

• Overuse of species harms ecosystems• Driven by greed, ignorance, desperation, poor

management• Overcutting forests, overgrazing, overhunting, etc.

• Trade in exotics: much trade is illegal• Illegal trade generates $12 billion/yr, the third largest

source after drugs and guns• Consumers pay huge prices for “luxuries” (e.g., polar bear

Consequences of losing biodiversity• Biodiversity is essential for ecosystem goods and

services• Mangroves and coral reefs buffer against storms • Ecotourism depends on biodiversity

• Energy flow and nutrient cycling are driven by species• Keystone species: species whose role is vital to

survival of other species• Predators control herbivores• Umbrella species: larger animals that need unspoiled

habitat (wolves, elephants, tigers, moose, etc.)

Highway overpasses

Cougar on the roof

Endangered Species Act (1973)• Endangered species: in imminent danger of becoming

extinct if it is not protected• Includes genetically distinct subpopulations (subspecies)

• Threatened species: in jeopardy but not yet endangered• An officially recognized endangered or threatened species• Fines are levied for killing, trapping, uprooting (plants), or

engaging in commerce • Administered by the U.S. Fish and Wildlife Service and

the National Oceanic and Atmospheric Administration Fisheries Service

Endangered species

Elements of the Endangered Species Act• Listing: by the appropriate agency, individuals,

groups, state agencies• Based on the best available information• Does not include any economic impact of listing

• Critical habitat: areas where a species is or could spread as it recovers• Includes privately held lands

• Recovery plans: designed to allow listed species to survive and thrive• Developed by the appropriate agency

The American bald eagle

The Red List• Maintained by the IUCN for threatened species• Evaluates the risk of extinction for thousands of species

• Frequently updated and available on the Internet• In 2008, it had 16,928 species

• Each species is classified • Given its distribution, documentation, habitat, ecology,

conservation measures, and data sources

• Not actively engaged in preserving species• It is the basis of conservation activities• Provides crucial leadership

Critical ecosystem partnership fund• Sponsored by multiple entities and foundations• Provides grants to NGOs and community-based

groups for conservation activities in biodiversity “hot spots”

• Hot spots are 34 regions making up 2.3% of Earth’s land surface• Contain 75% of the most threatened species

• By 2008, the fund had provided $102 million• 1,300 partners to work on preserving biodiversity in

these hot spots

Biodiversity hot spots

© 2011 Pearson Education, Inc. Value of wild species & biodiversity Ecosystem capital: goods &...

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