Project 4.3.2 the Life of a Tree

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

• Computer stations with Internet access, printing capabilities, and word processing software.
• Poster paper
• Marker pens
• Calculator
• Ruler

• Color pencils
• Glue sticks
• Scissors
• Project 4.3.2 Student Resources

• 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 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.

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

1. 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.

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:

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.

1. 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.
2. 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.
3. 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.

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.

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

• Provide your analyses of tree rings to support the weather data you calculated

• 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

Conclusion

1. What effect does rainfall levels have on the growth rate of plants, such as trees?

1. What effect does temperature have on the growth rate of plants, such as trees?

1. Explain how a woody perennial plant, such as a tree increases its trunk diameter.

The National Council for Agricultural Education – CASE – Copyright 2010

Plant – Unit 4 – Lesson 4.3 – Project 4.3.2 – The Life of a Tree – Page 1