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Class
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Skills Practice Lab
MATH/GRAPHING
Factors That Influence Ecosystems
Ecosystems are communities of plants, animals, and other organisms that live
and interact with each other and with nonliving environmental factors. The nonliving factors, or conditions, include temperature, precipitation, altitude, and
latitude, among others. These factors play an important role in determining what
types of vegetation can live in an ecosystem.
Latitude, for example, has a strong influence on an area’s temperature, resulting in climates such as polar, tropical, and temperate. These climates determine
different natural biomes that have characteristic species of plants. However, a
careful look at a map reveals that ecosystems existing at the same latitude often
have different climates. Why? In this laboratory activity, you will hypothesize how
other nonliving factors influence the characteristics of ecosystems within the
same latitude range. Then you will analyze and graph data from different areas of
the United States to test your hypotheses.
OBJECTIVES
Hypothesize how precipitation and altitude affect the types of vegetation in an
ecosystem.
Graph and analyze ecosystem data to confirm or refute your hypotheses.
MATERIALS
• colored pencils
• metric ruler
Procedure
1. Form two hypotheses—one that relates differences in ecosystem vegetation
to rainfall and another that relates differences in ecosystem vegetation to
altitude. Complete the following sentences to form your two hypotheses.
• Ecosystem distribution is related to precipitation; regions that receive large
amounts of precipitation are wet and therefore
.
• Ecosystem distribution is related to altitude; regions at high elevations are
cold and therefore
.
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Factors That Influence Ecosystems continued
Look at the data table. The table lists major U.S. cities and weather stations
between 36° north and 41° north latitude. It also lists the altitude, average annual
precipitation, and ecosystem for each location. On the graph/grid on the following page, use one of your colored pencils to plot altitude for each location using
the left-hand y-axis. Connect the data points. Plot the precipitation data in
another color, using the right-hand y-axis, and connect the points. You may also
find it useful to label the location names on the grid above your data points. Your
completed line graph will help you interpret any relation among rainfall, altitude,
and biome type.
CHARACTERISTICS OF LOCATIONS ACROSS THE U.S.
Distance from
San Francisco
(miles)
San Francisco, CA
Altitude above Average
sea level
rainfall
(feet)
(in./yr.)
Natural
biome or
ecosystem
0
250
23
redwood forest
Sacramento, CA
100
26
19
grassland
Donner Pass, CA
200
7,000
69
coniferous forest
Reno, NV
250
4,400
8
cool desert
Salt Lake City, UT
650
4,200
16
cool desert
Loveland Pass, CO
900
11,000
38
coniferous forest
Denver, CO
950
5,325
12
short grass prairie
Topeka, KS
1,450
925
34
tall grass prairie
St. Louis, MO
1,750
567
37
broadleaf forest
Cincinnati, OH
2,100
488
40
broadleaf forest
Washington, D.C.
2,500
9
39
broadleaf forest
Analysis
1. Identifying Patterns Which types of ecosystems occur in areas of high and
low precipitation?
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Factors That Influence Ecosystems continued
Distance in miles from San Francisco
0
1,000
2,000
3,000
4,000
5,000
10,000
15,000
0
San Francisco
500
1,000
1,500
An Ecological Transect Across the United States
2,000
0
2,500
10
20
30
40
50
60
70
Annual rainfall (inches)
Altitude (feet)
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Factors That Influence Ecosystems continued
2. Examining Data Is there a trend in the amount of precipitation from Denver
to San Francisco or from Denver to Washington, D.C.? If so, describe it.
3. Analyzing Results How do mountain ranges affect precipitation? Give an
example that supports your answer.
Conclusions
4. Evaluating Data Which is the more important factor in determining an area’s
ecosystem, the amount of precipitation or altitude? Is there an interaction
between these two factors? Explain.
5. Defending Conclusions Does the data support or refute your hypotheses
about the effects of precipitation and altitude on an ecosystem type?
6. Applying Conclusions Refer to the world biome map in your textbook.
Examine the ecosystem patterns of the Eurasian continent. What can you
infer about the distribution of rainfall in Eurasia?
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TEACHER RESOURCE PAGE
Skills Practice Lab
MATH/GRAPHING
Factors That Influence Ecosystems
Teacher Notes
TIME REQUIRED One 45-minute period
SKILLS ACQUIRED
Alyson Mike
East Helena
Public Schools
East Helena, MT
Classifying
Communicating
Identifying patterns
Inferring
Organizing and analyzing data
Predicting
RATING
Easy
1
2
3
4
Hard
Teacher Prep–1
Student Set-Up–1
Concept Level–2
Clean Up–1
THE SCIENTIFIC METHOD
Ask Questions Students are prompted to ask questions about the data as they
prepare to construct their graphs and when they use the data to classify the
biomes or ecosystems.
Test the Hypothesis Students test their hypotheses as they analyze their graphs.
Analyze the Results Students analyze the results of this laboratory activity
when they answer Analysis questions 1–3.
Draw Conclusions Students draw conclusions about the data presented in this
laboratory activity when they answer the Conclusions questions.
Communicate the Results Students communicate information as they formulate
their hypotheses, construct their graphs, and answer the questions at the end of
this activity.
TIPS AND TRICKS
Students can work individually or in pairs to complete this activity. Before students begin this activity, make sure they understand the difference between the
terms ecosystem and biome. An ecosystem is all the living and nonliving factors
that affect an organism. A biome is a major region that is characterized by its climate, soil type(s), and the dominant plants, animals, and other organisms that
live there. A biome is made up of many individual ecosystems.
Have students use their textbooks to review, if necessary, the definitions of the
terms used in this activity. Some students may need assistance in plotting the
data given in the table. If so, copy the transect grid onto an overhead transparency and use it to plot all of the data for San Francisco and at least one other
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Factors that Influence Ecosystems continued
city. Use different colors for the elevation and precipitation values. Remind students to include a key on their graphs that identifies the two sets of data.
Challenge interested students to add several more cities (within the same latitude
band) from other countries to the graphs and explain any variations.
When students have finished the activity, lead a discussion that will enable
them to conclude that rainfall and elevation are independent of latitude, while
temperature is not.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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Biomes
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Lesson
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TEACHER RESOURCE PAGE
Name
Class
Date
Skills Practice Lab
MATH/GRAPHING
Factors That Influence Ecosystems
Ecosystems are communities of plants, animals, and other organisms that live
and interact with each other and with nonliving environmental factors. The nonliving factors, or conditions, include temperature, precipitation, altitude, and
latitude, among others. These factors play an important role in determining what
types of vegetation can live in an ecosystem.
Latitude, for example, has a strong influence on an area’s temperature, resulting in climates such as polar, tropical, and temperate. These climates determine
different natural biomes that have characteristic species of plants. However, a
careful look at a map reveals that ecosystems existing at the same latitude often
have different climates. Why? In this laboratory activity, you will hypothesize how
other nonliving factors influence the characteristics of ecosystems within the
same latitude range. Then you will analyze and graph data from different areas of
the United States to test your hypotheses.
OBJECTIVES
Hypothesize how precipitation and altitude affect the types of vegetation in an
ecosystem.
Graph and analyze ecosystem data to confirm or refute your hypotheses.
MATERIALS
• colored pencils
• metric ruler
Procedure
1. Form two hypotheses—one that relates differences in ecosystem vegetation
to rainfall and another that relates differences in ecosystem vegetation to
altitude. Complete the following sentences to form your two hypotheses.
• Ecosystem distribution is related to precipitation; regions that receive large
amounts of precipitation are wet and therefore
.
Hypotheses may vary. Most students will probably state that ecosystems that
receive more precipitation will support more vegetation.
• Ecosystem distribution is related to altitude; regions at high elevations are
cold and therefore
.
Hypotheses may vary. Most students will probably state that ecosystems at
high altitudes will support little vegetation.
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TEACHER RESOURCE PAGE
Name
Class
Date
Factors That Influence Ecosystems continued
Look at the data table. The table lists major U.S. cities and weather stations
between 36° north and 41° north latitude. It also lists the altitude, average annual
precipitation, and ecosystem for each location. On the graph/grid on the following page, use one of your colored pencils to plot altitude for each location using
the left-hand y-axis. Connect the data points. Plot the precipitation data in
another color, using the right-hand y-axis, and connect the points. You may also
find it useful to label the location names on the grid above your data points. Your
completed line graph will help you interpret any relation among rainfall, altitude,
and biome type.
CHARACTERISTICS OF LOCATIONS ACROSS THE U.S.
Distance from
San Francisco
(miles)
San Francisco, CA
Altitude above Average
sea level
rainfall
(feet)
(in./yr.)
Natural
biome or
ecosystem
0
250
23
redwood forest
Sacramento, CA
100
26
19
grassland
Donner Pass, CA
200
7,000
69
coniferous forest
Reno, NV
250
4,400
8
cool desert
Salt Lake City, UT
650
4,200
16
cool desert
Loveland Pass, CO
900
11,000
38
coniferous forest
Denver, CO
950
5,325
12
short grass prairie
Topeka, KS
1,450
925
34
tall grass prairie
St. Louis, MO
1,750
567
37
broadleaf forest
Cincinnati, OH
2,100
488
40
broadleaf forest
Washington, D.C.
2,500
9
39
broadleaf forest
Analysis
1. Identifying Patterns Which types of ecosystems occur in areas of high and
low precipitation?
Forests are more common in areas of high rainfall, and deserts are more
common in areas of low-rainfall .
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Loveland
Washington, D.C.
10,000
Cincinnati
40
St. Louis
Topeka
30
Class
Altitude (feet)
50
5,000
20
4,000
3,000
2,000
10
Denver
Reno
Biomes
1,000
San
Francisco
0
Sacramento
0
San Francisco
500
1,000
1,500
Distance in miles from San Francisco
2,000
Altitude
Rainfall
0
2,500
Date
Salt Lake
TEACHER RESOURCE PAGE
70
Name
Donner
Factors That Influence Ecosystems continued
15,000
Annual rainfall (inches)
75
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An Ecological Transect Across the United States
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Date
Factors That Influence Ecosystems continued
2. Examining Data Is there a trend in the amount of precipitation from Denver
to San Francisco or from Denver to Washington, D.C.? If so, describe it.
Yes, there is a trend from Denver to Washington, D.C. Rainfall increases
toward the Atlantic Coast. Mountains interrupt the trend near San Francisco.
3. Analyzing Results How do mountain ranges affect precipitation? Give an
example that supports your answer.
Rainfall increases on the windward side, or the side facing the wind, of
mountain ranges. Donner and Loveland passes are good examples of this
effect. Locations on the leeward sides of mountains (the side not facing the
wind) have lower rainfall.
Conclusions
4. Evaluating Data Which is the more important factor in determining an area’s
ecosystem, the amount of precipitation or altitude? Is there an interaction
between these two factors? Explain.
Both factors are very important. Areas at higher elevations (Donner Pass)
tend to have forest ecosystems unless there is not enough rainfall, in which
case the area is a desert (Salt Lake City).
5. Defending Conclusions Does the data support or refute your hypotheses
about the effects of precipitation and altitude on an ecosystem type?
The data supports a hypothesis stating that precipitation nurtures ecosystems with lush vegetation. The data does not clearly support or refute a
hypothesis stating that increasing altitude negatively affects vegetation.
6. Applying Conclusions Refer to the world biome map in your textbook.
Examine the ecosystem patterns of the Eurasian continent. What can you
infer about the distribution of rainfall in Eurasia?
Eurasian ecosystems tend to have temperate deciduous forests near the east
and west coasts of the continent. As one travels toward the interior, forests
give way to grassland, and grassland gives way to desert. This implies that
the amount of rainfall decreases as one moves from coastal regions toward
interior areas.
Copyright © by Holt, Rinehart and Winston. All rights reserved.
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