Activity Materials for Students
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Resources and Downloads

This page contains the materials used in this lesson. If you click on the instrument, it downloads to your computer. If you use them in lessons you design please reference them so other teachers can find the material and mix and match like you have done.

CO2 Calculator This is an Excel spreadsheet. The spreadsheet calculates a tree's diameter from its circumference, height from 3 similar triangle measurements, tree's green weight from height, diameter and tree type, roots weight, total weight, dry tree root and total weight, carbon in tree root and total tree, CO2 in tree root total tree, equivalent CO2 from gasoline, natural gas, electricity or heating oil.

Dry weight - percent moisture comparison. This is an Excel spreadsheet that compares the dry weight of different kinds of trees with their percent of moisture. There isn't an obvious trend. Many questions don't give us the answers we expect. Since there isn't an obvious pattern, we should ask why not. If trees become completely saturated with water they sink. The reason they float is that the heart wood is dead and the cells have "air" in them like balloons. When these balloons fill with water the log sinks. The percentage of water relates to the percentage of cells that have water in them and how much water they contain. The dry weight of a tree is related to the ratio of cell wall to empty space in the cell. In dry weight the dominant factor seems to be the percentage of cells that are filled with water. There is a slight trend for heavy trees i.e. trees with relatively thick cell walls to interior ratios, to have less water. All other things being equal, that makes sense but most of the time the percentage of cells that are filled with water is so dominant that the two factors aren't equal. It is good for students to see that scientific explorations don't always proceed directly to the expected results. Even unexpected results are opportunities to gain insight.

CO2FIX V 2.0 This is the professional forest model used in this lesson. It was produced by the CASFOR project by G.J. Nabuurs, J.F. Garza-Caligaris, M. Kanninen, T. Karjalainen, T. Lapvetelainen, J. Liski, O. Masera, G.M.J. Mohren, A. Pussinen, and M.J. Schelhaas of ALTERRA, UNAM, CATIE and EFI at the Wageningen University and Research Center .

The software including input files can be downloaded free from the world wide web: http://www.efi.fi/projects/casfor

CO2FixWURex1 I transferred the stock and flow tables from the first sample forest provided with the CO2 Fix model to an Excel spreadsheet. Your students can analyze the data for this run. They won't be able to change the variables in the model for a new run. 

CO2FIXexharvest is the second sample model provided with their suggested changes to include harvesting of the forest. The flow and stock tables are in an Excel spreadsheet.

DGLBeedhComploggmort is a third sample forest provided with the model. Again, I copied the flow and stock tables to an Excel spreadsheet. This forest is a Douglas Fir and Beech plot with logging.

Tree diameter This is a web page that contains a JavaScript calculator to calculate a tree's diameter if you input its circumference. 

Tree height This is a web page that contains a JavaScript calculator to calculate a tree's height using similar triangles. You input distance to tree, distance from your eye to ruler, and apparent height of tree against the ruler. The calculator returns an estimate of the tree's height.

The following links are to web page calculators that return the green weight for their respective types of trees:

Yellow Poplar 


Soft Hardwood

Hard Hardwood

Southern Pine Coastal

Southern Pine Peidmont

Web page that calculates the dry weight of a tree based on its green weight and moisture content..

Web page that calculates the carbon in a tree based on its dry weight.

Web page that calculates the gallons of gasoline that are equivalent to a tree's carbon. 

The following are tables used to calculate the weight and dry weight of trees:

Table of tree type i.e. pine soft or hard hardwood

Table with percent water in green wood and dry/green ratio.


Developed by
Kent Robertson
Copyright © 2001

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.