Download Unit 4: Ecology - Parkway C-2

Unit 2: Population Ecology
Name _______________________________
Block _____
I. Population Growth
A. Population Density – the number of individuals per unit area; this number can vary depending on the species
and ecosystem.
Example: What is the population density if there are 200 FHC students in a classroom with an area of 40
square meters?
B. Population Growth Rate – the change in the number of individuals in a population over time. Calculated with
the following equation:
Growth 
 # organisms
time
C. Factors that Affect Population Growth
1. the # of births
2. the # of deaths
3. the # of individuals that enter or leave a population
→ Immigration – ________________________________________________________________
→ Emigration – _________________________________________________________________
D. Types of Population Growth
1.
Exponential Growth – occurs when the individuals in a population
reproduce at a constant rate, assuming unlimited resources and no
predators. In a graph, this type of growth forms a J-shaped
curve.
2. Logistical Growth – occurs when a population’s growth
slows or stops following a period of exponential
growth.
→ In a graph, this type of growth forms an S
-shaped curve.
? What causes exponential growth to slow or
stop in a population?
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E. Growth Curve – a graph showing the patterns of population growth over time.
1. Carrying Capacity – the maximum number of individuals that an ecosystem’s resources and space can
support.
2. Lag Phase – a time of little to no growth.
3. Exponential Phase – a time of rapid growt (population doubles over shorter and shorter periods of time).
Label the lag phase and exponential phase on the graph on page 1. Carrying capacity has already been labeled.
F. Limiting Factor – a factor that causes population growth to decrease.
1. Density- Dependent Factor – a limiting factor that depends on population size.
Examples:
2. Density- Independent Factor- a limiting factor that affects all populations in similar ways regardless of
population size.
Examples:
G. Human Population Growth
1. Demography – the study of human populations, looking at changes in birth and death rates and their
causes.
2. Demographic Transition – occurs when population shifts from a high birth and death rate to a low birth
and death rate. The result is that the population grows very slowly, if at all. Most
developed countries have experienced this.
3. The population of Earth continues to grow exponentially because most people live in countries that have
not completed demographic transition.
Examples of countries with exponential growth:
Use the graph below to answer the following questions.
What was the human population
in 9,000 B.C.?
What was the human population
in 6,000 B.C.?
What was the human population
in 1,000 B.C.?
What was the human population
in 1,500 A.D.?
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What was the human population in 2,000 A.D.?
Extrapolate the population for 2,010 A.D.
Label the lag and exponential phases of growth.
What factors spurred the exponential growth of humans in the 1900s?
4. Demographers can use age-structure diagrams
to predict the future growth of populations.
Is Rwanda a steady, growing, or shrinking
population, and how do you know?
Current projections suggest that the world
population will be 7.8 billion by 2025 and up
to 9 billion by 2050.
VII. The Effects of Human Activity on Population Growth
1. Hunting and gathering, agriculture, industry and urban development have all affected the biosphere.
2. The Industrial Revolution began in the 1800s, and humans began to rely on fossil fuels to run machinery
and to power cities and towns.
3. The increase in fossil fuel use has led to habitat loss, land erosion, water and air pollution, and toxic
wastes.
4. Urban Sprawl – _________________________________________________________________
_______________________________________________________________________________
Name some costs and benefits of urban sprawl.
Costs:
Benefits:
VIII. Natural Resources – the biotic and abiotic materials that support life on Earth.
A. Renewable Natural Resources – the materials that can be replenished in a relatively short time span.
1. Forests – communities dominated by trees and many different species of organisms.
a. Deforestation – the clearing of large areas of forested land for human use and consumption.
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b. Reforestation – the process of man replacing trees to reverse deforestation.
2. Wildlife – all plants and animals in a community that are interdependent on one another.
a. Endangered Species – those organisms that are at risk of extinction in their native habitats.
b. Threatened Species – those organisms that are likely to become endangered in their near future.
c. Endangered Species Act (1973) – passed by the U.S. government to define endangered species and
establish regulations for their protection.
3. Soil – a mixture of rock fragments, minerals, and organic matter.
a. Soil is renewed by erosion and decaying organisms. Plants and animals rely on soil for nutrients and
water, and soil relies on plants and animals to prevent destructive soil erosion.
b. Desertification – ______________________________________________________________
_____________________________________________________________________________
How does man help prevent soil erosion and depletion?
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4. Water – essential to all life, only 3% of the water on Earth is usable by man.
? How does man get by on such little water?
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B. Nonrenewable Natural Resources – those materials in nature that cannot be replenished by nature or man.
1. Fossil Fuels – formed as a result of incomplete decay of prehistoric plants and animals living in the
Carboniferous period about 300 million years ago. Fossil fuels are used for over 90% of
our energy needs.
Examples:
What are some alternative energy sources to fossil fuels?
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2. Minerals – inorganic solids formed in earth (iron, silver, aluminum, copper, zinc, etc.)
a. used to maintain normal body structure and function.
b. serve as building materials.
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3. Air – composed of a mixture of gases, including N2 (78%), O2 (21%), and CO2 (.03%)
a. Smog – ______________________________________________________________________
b. Acid Rain – __________________________________________________________________
c. Ozone Layer - _________________________________________________________________
_________________________________________________________________


There has been thinning of the ozone layer from excess CFCs in the atmosphere
CFC’s have been banned, so now the ozone layer can begin to slowly recover.
d. Greenhouse Effect– An excess of CO2 and other gases (like methane, water vapor) traps the sun’s
heat in Earth’s atmosphere, resulting in increased temperatures thus global
warming.
IX. Biodiversity
A. Ecosystem Diversity – includes the variety of habitats, communities, and ecological processes in the living
world.
B. Species Diversity – the number of different species in the biosphere.
C. Genetic Diversity – the sum total of all the different forms of genetic information carried by all organisms
living on Earth today.
Why is biodiversity important?
D. Human Effects on Biodiversity
1. Humans reduce biodiversity by altering habitats, hunting species to extinction, introducing toxic
compounds into food webs, introducing foreign species to new environments.
2. Habitat Fragmentation – breaking up an organism’s habitat.
→ fewer species live in the habitat.
→ populations become smaller and more vulnerable to other disturbances.
→ alters migration routes for some species.
3. Pollution – a negative or undesirable change in the physical, chemical, or biological characteristics of an
ecosystem.
4. Pollutants – cause of pollution.
→ Biodegradable – substances that can be broken down or decayed by microorganisms and fungi.
Examples: ___________________________________________________________________
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→ Non-biodegradable – substances that cannot be broken down or decayed by microorganisms and fungi.
Examples: ___________________________________________________________________
5. Biological Magnification – concentration of a harmful substance increases in organisms at
higher trophic levels in a food chain or food web.
6. Non-native species - (Invasive, exotic, alien, nonindigenous) – species migrate (naturally
or by human introduction) into areas where they have not
previously lived. This disrupts the food web of that habitat.
 Crown vetch plant is used along roadsides to prevent erosion, but it takes over
large areas and native plants can’t compete, so native animals have less nutritious
food.
 Zebra mussels, immigrants from E. Europe/W. Asia in shipping vessels, remove so
many nutrients from our fresh water lakes and rivers that native mussels and
other organisms cannot find enough food. They also clog water drains, cover boat
docks and bridge posts and are very expensive to remove.
 Feral Hogs – tear up soil causing erosion, killing native plants, and creating mud
holes where mosquitoes breed. In Hawaii, this has led to spread of diseases in
native birds.
Human Activity
Describe Specific Example
Negative Impacts
Ways to reduce or
reverse the negative
impact
Pollution
Habitat
Fragmentation
Over Fishing
Introduction of
Invasive Species
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Test #3B Format: Ecology
Test Date: _____________
1-30 = Multiple Choice
 Be able to determine “Population Density” and “Population Growth” (page 1)
 Factors that affect “Population Growth” (page 3)
 Density Independent vs. Density Dependent Factors (page 2)
 Factors that spurred exponential growth of the human population (page 3 )
 Renewable vs. Nonrenewable Natural Resources (pages 3)
 What % of water on earth is usable (fresh) by man (page 4)
 Be able to describe alternative energy sources to fossil fuels (page 4)
 Terms – Air, Smog, and Acid Rain (page 5)
 Define Diversity and know why it is important (page 5)
 What is Biological Magnification (page 6)
 What is Ozone and what affects the thickness of the ozone (page 5)
 What is the Greenhouse Affect/Global Warming and what are its causes (page 5)
61-73 = Completion and Constructed Response

Analyze a graph. Be able to label all phases of growth, the type of growth, and the carrying capacity of the
habitat (page 2)

Be able to discuss the pro’s and con’s of urban sprawl (page 3)

Explain what is meant by Biodiversity. (page 5)

Identify 2 benefits or services we receive by maintaining high biodiversity in ecosystems (page 5)

Describe one way that human activities reduce or threaten biodiversity. (page 5

Use 2 graphs to answer the following questions:
Identify the overall relationship between the concentration of CO 2 and changes in atmospheric
temperature.
Describe one way in which humans have contributed to the increase in atmospheric carbon dioxide
Describe one specific negative effect the continued rise in temperature would be likely to have on an
ecosystem
Describe one example of how humans are trying to reduce the problem of global warming .
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