Chapter 5 biodiversity and conservation
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Chapter 5 Biodiversity and Conservation. "For if one link in nature's chain might be lost, another might be lost, until the whole of things will vanish by piecemeal." - Thomas Jefferson

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Chapter 5 Biodiversity and Conservation

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Chapter 5 biodiversity and conservation

Chapter 5 Biodiversity and Conservation

"For if one link in nature's chain might be lost, another might be lost, until the whole of things will vanish by piecemeal."- Thomas Jefferson

"We consider species to be like a brick in the foundation of a building. You can probably lose one or two or a dozen bricks and still have a standing house. But by the time you've lost 20 per cent of species, you're going to destabilize the entire structure. That's the way ecosystems work."- Donald Falk, Christian Science Monitor, 26 May 1989

Corbis.com


Vanishing species 5 1

Vanishing Species (5.1)

  • Biodiversity – variation in life in a given area or ecosystem.

  • A orchard is much less diverse than a rainforest (fewer creatures/unit of area).

  • Species of mammals: Canada:163, U.S.: 367, Mexico 439….terrestrial biodiversity increases as you approach the equator.

  • 2/3 of all land species are in the tropical regions…warm wet areas.

  • Islands: large islands have more diversity than small. More space for variety...frequently protected parks become “islands” in human habitation.


Why is biodiversity important

Why is Biodiversity Important?

  • Diversity is pleasing to us; different lifeforms make the planet beautiful.

  • Organisms are adapted to live in communities…they depend on one another. Losses result in losses in all of community (see opening quotes). Life depends on life.

  • Biodiversity equals stability. The less variety is present, the more easily large portions die at once. Pests eat all of a cornfield, but just a few forest plants.

  • We are part of the ecosystem. If it becomes brittle and endangered through loss of diversity (above), so do we.

  • eg., air, diverse diets, CO2 removal, virtually all medications start as isolates from living things…penicillin, quinine, aspirin, cancer drugs…


Chapter 5 biodiversity and conservation

Dodo bird, Mauritius, extinct by 1681.

  • Loss of Biodiversity:

  • Extinction: loss of a species when last members die off forever.

  • 40 known species lost in U.S. since 1980 alone. Passenger pigeons, woodland caribou, prairie voles…

  • Can be natural causes, of late, many due to humans…mostly habitat destruction.

  • Threatened species: one whose population begins to decline rapidly. (African elephants, loggerhead sea turtles, sea otters...)

  • Endangered Species: one whose population is low enough to pose extinction threat (condors, manatees, black rhinos).

Passenger Pigeon, N.America, last one died in 1914 in the Cincinnati zoo.


Chapter 5 biodiversity and conservation

  • In 1806 Alexander Wilson (American ornithologist) noted while watching a migratory flight "It was then half past one (when the birds first appeared in the sky). About four in the afternoon, the living torrent above my head seemed as numerous and extensive as ever." Wilson estimated that in less than 3 hours he had seen a little more than 2 BILLION birds. In 1813 Audubon watched a similar 'torrent' of life that lasted for 3 DAYS. The last surviving bird died on September 1,1914 at the Cincinnati Zoo, having been commercially hunted to extinction. (from foodreference.com)

  • "Before sunset I reached Louisville, distant from Hardensburgh fifty-five miles, the pigeons were still passing in undiminished number, and continued to do so for three days in succession. The people were all in arms. The banks of the Ohio were crowded with men and boys, incessantly shooting at the pilgrims, which there flew lower as they passes the river. Multitudes were thus destroyed. For a week or more, the population fed on no other flesh than that of pigeons, and talked of nothing but pigeons." - John James Audubon, The Birds of America, 1844.

  • Between 1866 and 1876, nearly 12 million nesting pigeons were killed.(from Ohio History Central)

    A monument to the passenger pigeon in a Wisconsin State Park declares: "This species became extinct through the avarice and thoughtlessness of man.“

Passenger pigeons laid only one egg per nesting…


Chapter 5 biodiversity and conservation

  • Threats to Diversity- that can result in extinctions, etc.

  • Habitat loss. Biggest threat, esp. rainforest, coral reefs, and very diverse and stable environments.

  • Habitat Fragmentation – island effect. Areas cut off by roads and urban sprawl become virtual islands. Migratory species and larger animals (need large food gathering areas) are problem, can’t survive in restricted areas.

  • Reestablishment problem. Normally species wiped out of an area will replenish from elsewhere. If area is an “island” there is little opportunity for that.

  • Edge effect: inability of edges of environment to sustain full life means areas too small die out from the edges (drying forest edges example).

C – D.Lambert

Moa, extinct around 1800 in New Zealand

G. Cox


Chapter 5 biodiversity and conservation

Habitat Degradation: damage to habitat due to pollution.

Air, water, or land.

Air: breathing problems, irritating membranes, acid rain damaging soil, trees, changes lake pH. Burning of fossil fuels is chief cause.

Ozone damage. O3 protects earth like sunscreen. Extremely vulnerable to oxidizers like chlorofluorocarbons (CFCs). Breakdown results in skin cancer and amphibian worldwide declines.

Water: industrial, animal waste, fertilizers, silt on coral reefs. Fertilizers often result in large algal blooms in water, die, decay, remove all oxygen. Results in loss of species and fish deaths. (This is common in our area).


Chapter 5 biodiversity and conservation

Land: landfills, pesticides, chemicals. DDT (banned in U.S.) actually relatively nontoxic to humans in small amounts, but does not break down and accumulates in tissue. Thus passed higher and higher up food chain, concentrated.

Introduction of exotics: new species introduced to environment. Can be deliberate (bringing in a new garden plant or bug to control a weed) or accidental (sea lampreys making it into Great Lakes via canals). Exotic species are not native to a particular area. They can grow exponentially (no competition/predators) and take over niches, prey on native species, destroying them.


5 2 conservation of biodiversity

5.2 Conservation of Biodiversity

  • Conservation biology: new field, studies means of protecting biodiversity. Based on ecology principles.

  • Resource conservation, species conservation, soil conservation…work with people b/c people are often primary cause.

  • 1973, Endangered species act legally protects species on endangered or threatened species lists. Thus recoveries in Am.Bald eagles, alligators, brown pelican. Also international agreements (Convention on International Trade in Endangered Species [CITES]).

  • Conservation focuses on protecting whole communities/ecosystems…National Parks, whole community group…thus preventing many extinctions.

  • Sustainable use let people use resources if not harmful to the environment. Local people valuing their forest area is very important.

  • Patches of preserved area must be connects by natural strips that allow the migration of organisms from one area to another: habitat corridors.

  • Reintroduction programs-another strategy. Animals die out of an area permanently and are returned via moving them in from other native areas, or reintroducing them from captivity.

  • Captivity – a situation in which a species dies out in wild and exists only as preserved by human activity (ginkgo tree, Cal. Condors). More successful with plants (less expensive, animals can quit wild behaviors or lose their marbles in other ways.


The end

The End


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