Human Impacts

1
Human Impacts

• Part One How We Impact Habitats and Extinction
  of Species

2
Biodiversity

• Biodiversity is a measure of how many species are
  found in an ecosystem.
• There is a lot of natural variation in
  biodiversityRainforests may have six times as
  many species as Polar regions.

3
Biodiversity (continued)

• Biodiversity can be used as an indicator of the
  health or resilience of an ecosystem.
• Humans often deliberately create areas with no
  biodiversity.
• This is called monoculture.

4
What Can Happen When Theres No Biodiversity?

• In the early 1800s, millions of Irish were
  dependent on one type of potato (called the
  lunger) for most of their calories.
• In 1845, a fungus named Phytophthora infestans
  infected the potato crop.

5
The Irish Potato Famine

• The potato crop was completely destroyed for two
  years in a row.
• A million Irish died of starvation. Hundreds of
  thousands immigrated to other countries
  (especially America). Ireland has never truly
  recovered.

6
BiodiversityIts a Good Way to Hedge Your Bets.

• The Irish Potato Famine could have been avoided
  if farmers had planted more than one varieties of
  potato.
• The Lunger type of potato had no resistance to
  the blightbut other strains of potatoes were
  resistant.
• Diverse species are sources of different genes.
• Those genomes may hold answers to questions we
  havent even asked yet!

7
What Else is Biodiversity Good For?

• 1. 25 of our medicines come from plants!
• Example Foxglove, Rosy Periwinkle
• 2. Plants and animals are sources of food and
  fibers.
• 3. Species have Intrinsic Value.

8
Extinction

• Extinction The irreversible loss of a species
  by death of all individual members of that
  species. (1,999 of every 2,000 species that have
  ever lived are now extinct.)

Background Extinction a natural, low level
extinction of species that has occurred
throughout past Earth history.
Mass Extinction When numerous species disappear
during a relatively short period of geologic
time. This has happened five or six time in past
Earth history
Extinctions Today Increase in human population
and activities is causing a much higher than
normal rate of extinction.
9
Many Frog Species Becoming Extinct
In such diverse places as Australia, Brazil,
Costa Rica, Denmark, and California large numbers
of frog species are becoming extinct.
Why?
Frogs have extremely permeable skin, especially
on their bellies. It readily absorbs almost
anything in their habitat, including pesticides
and other chemical pollutants. Because of the
extreme sensitivity of frogs they are becoming
known as a bellwatcher species.
10
Reduction of Biodiversity

• Some species are always going extinct (one out of
  every million species per year).
• In some rainforests, human activity alone has
  increased that extinction rate by 1000 to 10,000
  times the normal background rate.

11
Endangered Species
When a species numbers are so severely reduced
that it is near extinction.
Why??
1. Extremely small range or niche.
2. A range that has been extensively modified
by Humans.
3. Living on islands.
4. Low reproductive success.
5. Highly selective feeding habits.
6. Extremely limited gene pool.
12
Threatened Species
When extinction is less imminent but the
population of a particular species is quite low.
13
Major Threats to Biodiversity

• Habitat Destruction
• (roads, parking lots, buildings, dams, fences,
  mining, etc.)

Introduced, Invasive, or Exotic Species (Frogs,
Mosquito Catcher, Blue Water Hyacinth, Red Cedar)
Competition (Limiting Factors) (sunlight, food,
water, temperature, soil, nutrients, or space)
Over Use (fishing, hunting, harvesting,
production, recreation)
Predator and Pest Control (DDT, PCB, 2-4D,
genetic resistance, cumulative effects, extended
kill)
Chemical Pollution (Petroleum, food additives,
heavy metals, fertilizer nutrients)
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Habitat Destruction

• Destruction of Habitat is at least partly to
  blame in 73 of cases where species have become
  extinct, endangered, threatened, rare, or
  vulnerable.
• Only about 3 of the land surface is protected in
  Parks and Preserves.

15
Wildlife Corridors

• Well-intentioned efforts have been made to leave
  pockets of habitat as preserves.
• A species that requires a great deal of territory
  is at a disadvantage in this situation.

16
Activities that Cause Habitat Loss

• Logging
• Grazing
• Urbanization
• Corporate Farming
• Mining
• Recreation
• Road Building
• Fencing
• Dams

17
Native or Introduced Species

• Humans have a Global Community and thats a good
  thing for us.
• Its not so good for native species.

18
Some Other Examples

• Kudzu vine was introduced from Japan in 1876 as
  an ornamental plant. During the Dust-Bowl years
  it was promoted to control soil erosion.
• You must close your windows at night to keep it
  out of the house. James Dickey

19
Examples of Introduced Species, Continued

• Starlings, house sparrows, and rock doves were
  all introduced from Europe because Europeans
  believed that their native birds were superior
  to native American varieties.

20
Examples, continued...

• The Nile Perch was introduced to Lake Victoria in
  the 1950s.
• Since then, the number of species of cichlids in
  Lake Victoria has gone from 300 down to 100200
  species gone forever.

21
Overuse

• Traditional examples Bison were once slaughtered
  for meat, hides, and just to eradicate the food
  supply of Native Americans
• Whales hunted for whale-oil to light lamps in the
  1800s
• Large predators such as tigers and cheetahs taken
  for their skins

22
Overuse Continued

• More recent examples
• Bushmeat monkeys and apes in Africa
• Black Rhinos hunted for their horns
• Sharks hunted for Sharkfin soup

23
What does that loss of diversity do in terms of
energy flow in an ecosystem?
24
Do Humans Have any Positive Influences on Species?

• Weve been trying hard since the 1970s!
• Conservation Biology is a major field of
  research.
• The Endangered Species Act and laws like it have
  saved species such as the Peregrine Falcon, Bald
  Eagle, Wolves, California Condor, etc.

25
We Have Some Decisions to Make

• Sometimes its simply not possible to save every
  species.
• Economics plays a big role. What if it comes
  down to a choice between jobs and species?

Spotted Owl
26
Is It Worth It?

• Sometimes our efforts to save a species are
  extremely expensiveand ineffective.
• Millions of dollars have been spent on saving the
  California Condor. So far, there are about 200
  of them.

27
Keystone Species

• One important consideration is to preserve
  Keystone Speciesorganisms whose role in the
  ecosystem is very important.
• Species affected if Prairie Dogs disappear bald
  and golden eagles, swift foxes, coyotes,
  ferruginous hawks, burrowing owls, badgers and
  black-footed ferrets.

28
Other Environmental Issues Caused By People

• Major expansion of human population
• Pollutions caused by nuclear energy
• Water pollution
• Gene pool decline
• Soil pollution
• Acid precipitation
• Introduction of exotic species
• Destruction of tropical rain forests
• Ozone Depletion
• Oil spills
• Global climate change

29
Human Population Increasing
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Is There Anything You Can Do?

• The effort of every person counts.
• Conserve energy and natural resources.
• Reduce waste.
• Make sure you are well informed about
  environmental issues.
• Share your knowledge about environmental issues.
• Be committed to solution of environmental issues.