slide1 l.
Skip this Video
Loading SlideShow in 5 Seconds..
CHAPTER 20 Human Impacts on the Environment PowerPoint Presentation
Download Presentation
CHAPTER 20 Human Impacts on the Environment

Loading in 2 Seconds...

play fullscreen
1 / 50

CHAPTER 20 Human Impacts on the Environment - PowerPoint PPT Presentation

  • Uploaded on

CHAPTER 20 Human Impacts on the Environment. Outline: I. Introduced species II. Human impacts III. The biodiversity crisis IV. Conservation biology V. The goal of sustainable development. About 12% of all known bird species are endangered.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'CHAPTER 20 Human Impacts on the Environment' - taite

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

CHAPTER 20 Human Impacts on the Environment


I. Introduced species

II. Human impacts

III. The biodiversity crisis

IV. Conservation biology

V. The goal of sustainable development

i introduced species
I. Introduced Species
  • Are species that humans intentionally or accidentally move from the species’ native (home) locations to new geographic regions.
  • Examples:
    • The European starling
    • Argentine ants
    • The zebra mussel

What is the number of introduced species in the US?

Can you name some species native to the US?

ii human impact on ecosystems
II. Human Impact on Ecosystems
  • Human population has markedly changed natural habitat systems.
    • A. Impacts on Chemical cycles
      • Carbon- increased burning of fossil fuels
      • Nitrogen & Phosphorus - fertilizers & sewage treatment facilities 
      • Water – irrigating crops & deforestation



Deforestation burning

human impacts of releasing toxins
Human impacts of releasing toxins
  • The release of new toxic materials cannot be degraded by microorganisms
  • Toxins can accumulate in tissues of animals
  • Biological magnification
    • A process in which toxins become more concentrated in successive trophic levels of a food web



human impact on the atmosphere and climate
Human Impact on the Atmosphere and Climate
  • Carbon Dioxide Emissions
    • Since industrial revolution CO2 has increased in atmosphere
  • The Greenhouse Effect
    • Retains solar heat in the atmosphere
  • Increased global temperatures have potentially disastrous consequences

Burning fossil fuel

Remember the film?


How do changes in number of producers and consumers influence production and uptake of global CO2?

How do different types of industry influence global CO2?

Depletion of Atmospheric Ozone
    • The ozone layer absorbs UV radiation
    • Thinning since 1975 due to CFC’s
    • Consequences-
      • Increased skin cancer, cataracts
      • Amphibian population declines
iii the biodiversity crisis
III. The Biodiversity Crisis

is serious!

  • Human activity is causing a decline in the Earth’s great variety of life
  • A. Biodiversity has three main components

1. the diversity of ecosystems

2. the variety of species that makeup communities

3. the genetic variation within each species


Tropical rain forest

...full of biodiversity!

B. The Loss of Species
  • The current mass extinction - worldwide
    • Caused by human activity
    • Broader & faster than past extinctions
    • 12% of known bird species
    • 24% of known mammal species are threatened with extinction
    • Biologist Edward O. Wilson has compiled the Hundred Heartbeat Club
      • Species with fewer than 100 individuals

< 100 ww!

Philippine eagle

Chinese river dolphin

Javan rhinoceros

c three main causes of the biodiversity crisis
C. Three Main Causes of the Biodiversity Crisis
  • 1. Habitat Destruction
    • Is the single greatest threat to biodiversity
  • 2. Introduced Species
    • Ranks second behind habitat loss. Can cause rapid extinctions
  • 3. Overexploitation of wildlife

Human alteration of habitat


Introduced species

Lake Victoria, East Africa



Do you like bluefin tuna?

Do you eat sushi?

d why biodiversity matters
D. Why Biodiversity Matters
  • Humans rely on biodiversity for
    • Food, clothing, shelter, oxygen, soil fertility, medicinal substances
  • Endemic species
    • Are those found nowhere else
  • The loss of diversity
    • Limits the potential for new discoveries of food and medicine

Drugs from plants!

iv conservation biology
IV. Conservation Biology

A science that seeks to counter the loss of biodiversity

  • Biodiversity hot spots
    • Small areas with an exceptional concentration of species, including endemics

Terrestrial biodiversity hot spots

Notice California


Do you understand why its important to preserve biodiversity in CA?

conservation at the population species levels
Conservation at the Population & Species Levels
  • The U.S. Endangered Species Act (ESA)
    • Definition: endangered species
      • “…a species in danger of extinction throughout all or a significant portion of its range”
    • Definition: threatened species
      • “…a species likely to become endangered in the foreseeable future”
habitat population fragmentation
Habitat & Population Fragmentation
  • Fragmentation can results in
    • A decrease in the overall size of populations
    • A reduction in gene flow among subpopulations
    • Harmful side effect of human habitation

Consequence: severe habitat degradation


Mt. Hood National Forest


Northern spotted owl

what makes a good habitat
What Makes a Good Habitat?
  • Identifying the specific combination of habitat factors that is critical for a species is fundamental to conservation biology
    • Example: Polar Bears
conserving species amid conflicting demands
Conserving Species amid Conflicting Demands
  • Competing demands for habitat
  • Edges and corridors between ecosystems
    • Promote dispersal & help sustain populations
    • Especially important to species that migrate between different habitats seasonally
  • Jobs in
    • Timber
    • Mining
  • Loss of livestock
  • Camping safety
  • The owl
  • Wolf
  • Grizzly bear
  • Bull trout



Edges created by human activities

Heavily logged rain forest in Malaysia

v the goal of sustainable development
V. The Goal of Sustainable Development
  • Sustainable development
    • Balances human needs with the health of the biosphere
  • The goal of sustainable development
    • Is the long-term prosperity of human societies and the ecosystems that support them
some ways you can promote sustainability
Some Ways You Can Promote Sustainability

Reduce consumption

  • Buy less
  • Avoid excess packaging
  • Avoid products make from non-renewable resources
  • Fix things rather than discarding them

Be more energy efficient

  • Bike, walk, take public transportation, drive less
  • Share rides
  • Purchase efficient appliances and vehicles

Promote recycling

  • Recycle at home and at work
  • Purchase products made from recycled materials

Promote research and education

  • Talk about environmental issues with friends, family
  • Sponsor environmental initiatives on your campus
  • Serve as a role model through your actions

…more on Table 20.1

biophilia and an environmental ethic
Biophilia and an Environmental Ethic
  • Edward O. Wilson
    • Biophilia

 the human desire to affiliate with other life in its many forms, is innate

Do you have pets?



1. Severe population _________ is one of the most severe consequences of habitat degradation.

2. Carbon dioxide traps heat and warms the atmosphere, a process called the _________ effect.

3. It is hard to protect species such as the monarch butterfly, sea turtles, and many songbirds, because they _________.

5. Fertilizer runoff can result in the _________ of lakes.

6. The goal of _________ development is to ensure that each generation inherits adequate resources and a stable environment.

7. Most biodiversity hot spots are in the _________.


8. Biological _________ of pesticides harms animals at the top of the food chain.

10. Human alteration of _________ is the greatest threat to biodiversity.

14. The Earth is facing a serious _________ crisis.

18. The _________ is a law that protects endangered and threatened species.

20. In the US, 25% of prescriptions contain substances derived from _________.

22. Burning of _________ fuels produces carbon dioxide that may contribute to global warming.


Reading Assignment for:

Next week, 12/4/07 & 12/6/07

Chapter 17

The Evolution of Animals