Project 4.3.2 – The Life of a Tree
Purpose
Some trees have been in existence in North America long before the United States
was a country. These old growth trees have a record of climatic conditions that
existed during the growing seasons for plants during their life span long before
human records where kept.
Each tree ring typically represents one growing season, or for human time, one
calendar year. You can make a reasonable estimate of a tree’s age by counting
rings. However, by studying patterns of ring growth, you can also determine how the
climate affected the growth of trees and other vegetation.
This project will compare tree growth rings of a Douglas fir tree with the most
complete weather data available for its growing region in the Pacific Northwest. To
put the tree’s life in perspective, you will research historical events that correspond
to patterns of tree growth. After compiling weather and historical data, your group
will assemble a poster to represent a segment of the tree’s life.
Materials
Per group of four students:
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Computer stations with Internet
access, printing capabilities, and
word processing software.
Poster paper
Marker pens
Calculator
Ruler
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Color pencils
Glue sticks
Scissors
Project 4.3.2 Student Resources
Per student:
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Pencil
Agriscience Notebook
Procedure
In a group of four students determined by your teacher, you will be using the clues
found in the stem growth of plants to make a record of the seasonal growth rate of a
tree. Your group will also determine historical and pop culture events that occurred
during the same time period you are examining.
By the conclusion of this project, you will understand how temperature and
precipitation can affect the rate of stem growth in perennial plants, such as trees.
You will also have points of reference to provide perspective about human life while
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Plant – Unit 4 – Lesson 4.3 – Project 4.3.2 – The Life of a Tree – Page 1
the tree was alive. Each group will develop a poster depicting a segment of time in
the tree’s life.
Part 1 – Estimating the Age of a Tree
Your group will determine the age of the tree by using the cross section of a tree
picture provided in Project 4.3.2 Student Resources. By counting the growth rings,
you can estimate the age of the tree in years fairly accurately. The scientific process
of dating trees using this method is called dendrochronology. Although it is a good
way to estimate the age of a tree, some situations occur that make this method
imperfect, such as changes in climate.
Some dates have been provided to help guide you through the counting process.
The tree was harvested in 2006, but your first task is to determine when it started
life.
Estimated first year of growth of the tree: _____________
Part 2 – Examining the Effects of Weather
Once the age of the tree has been determined and agreed upon with the class, your
teacher will divide the years of life for the tree by the number of groups in your class.
Next, your teacher will assign a segment of the tree’s life span to your group to
research. The first aspect to research is the effects of weather on the growth of the
tree.
1. Find the rainfall and temperature data for the tree’s life segment your group is
researching in the Project 4.3.2 Student Resources.
2. Determine the average rainfall totals and temperatures for each growing season.
The growing season for your tree is April through October. Therefore, you
will need to add up the monthly totals for only those seven months and divide by
seven to get the average rainfall and temperature for each growing season.
3. Compare the annual averages with the historical average for those months to
determine if each growing season was below or above average in rainfall total
and temperature. The historical average for the months of April through October
is:
 Rainfall = 1.72 inches
 Temperature = 60.32 ºF
4. Find groupings of rings based on the spacing between each. If several rings are
close together, compare the weather data for that grouping with another grouping
when the rings are spaced further apart. Develop a theory to explain ring spacing
based on mean rainfall totals and temperatures present during the growing
season of the tree.
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Plant – Unit 4 – Lesson 4.3 – Project 4.3.2 – The Life of a Tree – Page 2
When the rings of a tree are further apart, this indicates:
When rings are closer together, this indicates:
Why does the climate influence ring spacing?
Summarize your group’s conclusions for the effects of weather on tree growth
for the time segment your group is investigating:
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Plant – Unit 4 – Lesson 4.3 – Project 4.3.2 – The Life of a Tree – Page 3
Part 3 – Scaling Growth Projections
Anatomical differences can be determined for the stages of the life of a tree.
However, all trees look pretty much the same and do not have many noticeable
differences except for height and width. However, to get a snapshot of what the tree
would have looked like during your groups segment of the tree’s life, you will need to
provide a frame of reference.
1. Research the approximate size your tree would be during the segment of life you
are documenting.
2. Find a picture on the web or sketch a picture of a Douglas fir tree matching the
relative size determinations you determined for the tree height.
3. Select an everyday item that equals the tree’s dimensions. For example, if the
height is 6’0” then a good frame of reference is a person standing next to the tree
indicating the same height.
4. Prepare this illustration for the final project.
Part 4 – Historical Events
A little more research is needed to relate the life of your tree with perspective people
can appreciate. Your group will use the block of years that make up your group’s
segment of life for the tree and research the historical events that happened in
American or World history during those years. Your group will need four historical
references and may include one reference to local history if you wish.
Date event
Happened
Name or Explanation of Event
Place the Event
Happened
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Plant – Unit 4 – Lesson 4.3 – Project 4.3.2 – The Life of a Tree – Page 4
Part 5 – A Pop Culture Reference
Most people can relate well to pop culture from past history. For this part of the
project, your group will research what the most popular songs, movies, or vehicles
were for the segment of time for your tree’s life. As you did in Part 4, conduct some
research to determine four popular songs, movies, or vehicles for the time period
you are investigating.
Date
Played or
Shown
Name of Song, Movie, or Vehicle
Artist , Lead Actor, or
Manufacturer
Part 6 – FFA History
The National FFA Organization was founded in 1928 and has a long list of historic
milestones. Research and identify the major FFA events that happened during the
life span of the tree that your group is studying. Include these events as a timeline
across the bottom of your poster.
Part 7 – Putting it all Together
Create a poster illustrating the information your group has researched and analyzed
in the previous parts. Your poster should include the following:
 A title indicating the time duration your group studied
 Your determinations of the weather during this time period
o Provide your analyses of tree rings to support the weather data you
calculated
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The illustration made for the size and scale of the growth period
Illustrations and listing of historical events that happened during the
segment of time your group studied
Illustrations and listing of songs, movies, or vehicles popular during the
segment of time your group studied
FFA events timeline across the bottom of the poster
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Conclusion
1. What effect does rainfall levels have on the growth rate of plants, such as trees?
2. What effect does temperature have on the growth rate of plants, such as trees?
3. Explain how a woody perennial plant, such as a tree increases its trunk diameter.
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