StimulatingUnderstanding of Computational science through Collaboration,Exploration, Experiment, and Discovery for students with Hearing Impairments
a collaboration of the Shodor Education Foundation, Inc., Eastern North Carolina School for the Deaf, Barton College, the National Technical Institute for the Deaf, and Interpreters, Inc.

Notes on teaching the lesson: This inquiry-based lesson allows the students to explore some of the factors that effect changes in a tree species' range. The students use an Excel spreadsheet to determine the hardwood tree species that grow in their area. They collect information on these species from USGS and USDA sites. The students enter the data they have collected into a computer model. The model comes in two versions, Stella and Java. The Stella model has better graphics and allows the students to explore how the model works and potentially improve the model. The Stella model must be downloaded along with a free Save-disabled version of Stella. The Java model is available on a web page within this lesson.

Scientists work at the cutting edge of our understanding. Over time, our concepts become more refined and our ability to measure and predict things becomes more accurate. The background page introduces the students to the varying degree of certainty that we have for different aspects of global warming. As the students evaluate the effect of global warming, they are asked to express these effects in terms of the inherent uncertainty in the values. As scientists, it is important that we identify the uncertainty in our results. This allows others to appreciate the limits of our research and think of additional research that can further refine our collective understanding.

 This lesson is designed to help the students learn that science and computer models are valuable tools to solve real life issues. Using science allows the students to understand what happens and how it happens. From a societal standpoint, the value of science is in how we use this understanding. By applying their understanding of global warming, the students can see how science can be used by communities to protect the environment and to enhance the beauty and recreational value of our communities.

The following are the student pages. Answers and suggestion for the teacher are in BLUE.

Activity

Will global warming push trees to extinction?

This question assumes that a tree's range may shrink with rising global temperatures. This assumption in turn assumes that a tree's range is, at least in part, dependent on temperature. The first question to investigate is; "can you demonstrate a relationship between a tree's temperature tolerance and its geographic range?"

The United States Geological Survey provides Excel spreadsheets for hardwood and softwood trees. The data in the spreadsheets shows the percentage of trees of a species that are found in areas of different temperature and precipitation.

The table below shows part of that data. The common names of the trees were added to the USGS spreadsheet. The annual temperature spreadsheet was sorted to select trees that grow in the southeastern US. The 5 trees in the table are of the genus Acer. These are the maple trees that are native to the southeastern US.

HARDWOODS						Annual Temperature (°C)
Taxon name	Common name		N	0%	10%	25%	50%	75%	90%	100%
Acer barbatum	Florida maple		636	14.0	15.0	16.0	16.9	17.9	18.9	20.2
Acer leucoderme	chalk maple		191	14.1	15.3	16.0	16.6	17.1	18.4	19.9
Acer negundo	boxelder		6534	-2.3	2.5	6.0	10.1	14.7	17.9	26.1
Acer rubrum	red maple		4842	-1.1	3.3	5.8	11.1	16.1	18.7	23.8
Acer saccharinum	silver maple		3792	1.3	5.8	7.9	11.0	14.1	16.3	20.0

The column "Taxon name" is the scientific name for the tree. The column "N" is the number of trees that were identified out in the forests and used in the study. The 0% column is the annual temperature for the coldest tree that was found. For Florida maple that was 14 degrees Celsius. The 10% column shows the temperature that 10% of the trees grow at or below. For example, 10% of the Florida maple trees grow between 14 and 15 degrees Celsius. In the same way the 50% column shows the temperature that half of the trees grow at or below. The 100% column shows the warmest temperature that a tree was found.

From this data you can calculate the temperature range for each species. Acre barbatum grows in areas with annual temperatures that range from 14 to 20.2 degrees Celsius. This is a 6.2 degree Celsius range. Calculate the range for each species and arrange the species from smallest to largest temperature range.
 
 

scientific name	common name	low temp	high temp	range
Acer leucoderme	chalk maple	14.1	19.9	5.8
Acer barbatum	Florida maple	14.0	20.2	6.2
Acer saccharinum	silver maple	1.3	20.0	18.7
Acer rubrum	red maple	-1.1	23.8	24.9
Acer negundo	boxelder	-2.3	26.1	28.4

The second part of our question is, "What is the tree's geographic range?" Again the United States Geographical Survey provides maps of the areas where these trees are found.

Florida maple range

chalk maple range

boxelder range

red maple range

silver maple range

You need to determine the north- south range for each species of maple tree. This should be an uninterrupted line within the trees' range. Use a sheet of paper to help measure the north- south range. Put the lower left corner of the paper on the lower left corner of the trees range. Slide the paper to the right keeping the lower edge of the paper on the lowest side of the range. As the paper moves the trees range will move up and down the left vertical edge of the paper. Mark the highest point that the range reaches on the paper. If the range is in more than one block you will need to repeat this for each block selecting the largest distance.

Next you need to convert this distance to miles. The map doesn't have a key but the state boundaries are marked. If you know the north south dimension of a state you can use that state as a key. You can find the dimensions for states by going to netstate.com.

Arrange the maple tree species from smallest to largest north south range.
chalk maple
Florida maple
silver maple
red maple
boxelder

Compare your two lists.

Do the temperature and geographic ranges list the trees in the same order?
Yes
Explain the relationship between a tree's temperature tolerance and its geographic range.
The trees with a narrow temperature tolerance have a small geographic range. The larger the temperature range the larger the geographic range.
Defend or criticize the statement, "Global warming will change where we find a tree species."
There appears to be a relationship between the geographic range of a tree and the temperatures of the area that we find the tree. If the area in an area changes the trees in that area may be affected. Some trees may no longer be well suited to live there. Other trees may be able to move into the area. We see a relationship between the trees' temperature and geographic range but this may be coincidental.
Defend or criticize the statement, "Some tree species will be affected more that others by global warming."
Trees that have a large geographic or temperature range may lose some trees at the southern edge of the range but most of the trees will still remain in the tree's range. Trees who's seeds are dispersed over large areas by birds may be able to maintain their range by moving north as fast as the southern boundary of the range moves north. Trees with small initial ranges and or small propagation rates will see their ranges shrink or disappear. The students don't have evidence to support this yet but it is a reasonable hypothesis.
Model2

There are hundreds of different kinds of trees in North America. You won't have time to gather information on all of these tree species today. You need to have a way to narrow your investigation. You can start by finding the hardwood trees that live in your part of the country.

Open the hardwood Excel spreadsheet that comes with this lesson. This spreadsheet is from the U.S. Geological Survey web site http://pubs.usgs.gov/pp/1999/p1650-a/datatables/index.html

Select the "ANNT" worksheet. This shows the Annual Temperature distribution for 230 hardwood species. Columns M-R indicate which parts of the U.S. the trees are found. You can use columns M-R to sort the trees and find the kinds that live near you. Select cells A4 through S233. From the toolbar select "Data". From the "Data" menu select "Sort". A window will open that lets you select the column you want to use to sort the spreadsheet. North Carolina is in the South Eastern part of the U.S. so I select column "R" to sort the data.
Click "OK" and the spreadsheet will be sorted with the trees from your area at the top.
How many different kinds of hardwood trees grow in your part of the U.S.?
Answers will vary.
Divide the trees that grow in your area between the students in your class. You will need to gather three pieces of information for each of your tree species.

1 Find the current north - south range for each tree species. Use the same procedure you used in this lesson's activity page. Range maps can be found at the US Geological Survey CLIMATE - VEGETATION ATLAS.
Answers will vary.
2 Find the number of years it takes a tree to grow from seed to the point that it will produce its own seeds. This is the number of years between each step the tree species moves north
Answers will vary..
3 Find the distance from the parent tree that the seeds will grow. This is the propagation distance. Answers will vary.
A good place to start your search for the propagation distance and years to reseed is the US Department of Agriculture site TREES OF WESTERN NORTH CAROLINA. If your tree isn't listed on this site try a web search for the information.

Design a table to collect your information. After you have collected your data use the HABITAT RANGE MODEL to determine if your trees may become endangered.
Answers will vary.
What is the current range of your trees?
Answers will vary.
What range does the model predict for your trees?
Answers will vary.
How certain are you of this figure? Express your uncertainty in + miles. Answers will vary.
Need HELP CALCULATING YOUR UNCERTAINTY?

How much has the tree's range shrunk?
Answers will vary.
Is the tree in danger of becoming extinct?
Answers will vary.
Repeat the simulation for each tree species using different values for warming expected in the next 100 years.
Answers will vary.
Prepare a report of your finding. Make a recommendation of actions that should be take to protect trees that may become endangered or extinct.
Students may recommend that seed banks be created to preserve seed stock from trees that may become endangered. Students may recommend that an organized effort be undertaken to distribute seed from potentially endangered trees be distributed into the woods north of their current range to help the trees maintain a population within their preferred climate range. Some students may not see the value in maintaining rare species. They may feel that any efforts undertaken should voluntary and not government sanctioned.

This project is supported, in part, by the National Science Foundation Opinions expressed are those of the authors and not necessarily those of the National Science Foundation.