1. Populations and the
Environment
Chapter 5, 6.2 and 6.3

2. 5.1 How Populations Grow
Population Density
Population density is a
measurement of the
number of individuals
living in a defined
space.
Scientists can
calculate population
density.

3. 
Population dispersion
refers to how a population
is spread in an area.
Clumped
dispersion
Clumped
Uniform
dispersion
Random
Uniform
Random
dispersion

4. Population Growth


The size of a population is
always changing.
Four factors affect the size
of a population.




Immigration
Births rate
Emigration
Death rate

5. 
Population growth is based on
available resources.

Exponential growth is a rapid
population increase due to an
abundance of resources.

6. However,

Most populations are regulated by predators,
disease, and the availability of resources.


Because of this population will not exceed the
environmental carrying capacity
As a population grows, limited resources become
depleted and the growth of the population slows.

7. 

Logistic growth occurs when a population is
facing limited resources.
Carrying capacity is the maximum number of
individuals of a particular species that a
particular environment can support.

8. 5.2 Limits to Growth

Limiting factors – control the growth of a
population

Density-dependent factors
The rate at which they become depleted depends upon the
population density of the population that uses them.

Competition
 Predation
 Disease
 Overcrowding
 Herbivory


9. Example: Limiting Growth

10. 
Density-independent limiting factors limit a
population’s growth regardless of the size and
density.




Hurricanes
Drought
Floods
Wildfires

11. 1.During which time period is birth rate higher than death rate?
2.During which time period are birth rate and death rate equal?
3.During which time period is death rate higher than birth rate?

12. 5.3 Human Population Growth

For most of human existence, the
population grew slowly because life was
harsh.

Food was hard to find. Predators and diseases
were common and life-threatening.

These limiting factors kept human death rates very
high.

13. 
Improved nutrition, sanitation, medicine, and
healthcare, dramatically reduced death rates.

birthrates in most parts of the world remained high.

The combination of lower death rates and high birthrates led
to exponential growth.

14. 6.2 Using Resources Wisely

How do we obtain what we need from local and
global environments without destroying those
environments?
Environmental Resources we affect:
 Soil
 Freshwater
 Air

15. Soil Resources

Healthy soil supports both agriculture and
forestry.



Topsoil – rich in organic matter and nutrients
Loss of fertile soil can have dire consequences.
Erosion – removal of soil by water or wind
Desertification
 Deforestation


16. Desertification Risk

17. Soil Use and Sustainablility



Leaving stems and roots of the previous
year’s crops
Crop rotation
Select Harvesting

18. Freshwater Resources


drinking water, industry, transportation, energy,
and waste disposal.
Some farmland relies heavily on irrigation

19. Water Pollution
Many serious environmental problems
occur in our own backyard.
 Agriculture introduces large amounts of
chemicals into the global ecosystem.

Including: pesticides, herbicides, and
fertilizers

Many chemicals, such as DDT, have been banned in the
US, but the effects of their use still circulate.
Causes biological magnification


21. Water Quality and Sustainability



Protecting the water cycle
Clean up pollution
Conserve water

22. Atmospheric Resources

Air quality has a direct impact on health.


Pollution
Global temperature

23. Coal-burning power plants send smoke,
containing sulfur, into the atmosphere through
smokestacks.

Scientists now know that the sulfur can combine with water
vapor to produce sulfuric acid, which will fall back to earth as
acid rain.
Acid rain causes forest damage, and dead lakes

Robl, Ernest H. Acid Rain Damage. Photograph
1990. Web. 21 Oct 2010.

24. Decrease in the amount of ozone (O3) in the
atmosphere allows more UV radiation to reach
the earth’s surface.

This can cause an increase in diseases related to UV
exposure such as cancer and cataracts.
The major cause is chlorofluorocarbons (CFCs) commonly
used in refrigerators, air conditioners, and in aerosols.
As a result CFCs have been banned in the US.


25. Hole in the ozone layer
Rubin, Ken. “Ask an Earth Scientist.”
Hawaii.Oct 2008. Web. 8 No

26. The earths average global temperature has been
steadily increasing for more than a century
(Global Warming)

Caused by the greenhouse effect, in which greenhouse gasses
trap the suns energy within the atmosphere.


28. 
Earth’s resources must be used responsibly.



Careless use of resources makes them unavailable to
future generations.
An ecological footprint is the amount of land
needed to support a person.
The land must produce and maintain
enough




food and water
shelter
energy
Room for waste

29. Worldwide Ecological Footprints

30. Determine your ecological
footprint

Go to www.footprintnetwork.org/calculator to
determine how many planet Earths it would
take to support everyone if they lived like you.

31. 6.3 Biodiversity

Biodiversity is one of Earth’s greatest natural
resources. When biodiversity is lost, significant
value to the biosphere and to humanity may be
lost along with it.

32. The loss of biodiversity has long-term effects.




loss of medical and technological advances
extinction of species
loss of ecosystem stability

33. 
Habitat Fragmentation

34. Hunting and Demand for
Products

35. 
Introduced Species

Introduced species can disrupt stable relationships
in an ecosystem.
Burmese python in the Florida Everglades
Kudzu

36. Conservation


Conservation methods can help protect and
restore ecosystems.
Sustainable development meets needs without
hurting future generations.


resources meet current needs
resources will still be available for future use

37. 
Sustainable practices





Timber industry
Fisheries
The Endangered Species Act
Environmental Protection Agency (EPA)
National Park Service