“The Carbon Footprint Lab”
Biology I
How can we measure the amount of carbon stored in a tree?
Names_________________________
1. Choose a pine tree and measure the circumference at your chest height level. (inches) ___________
****All calculations can be done for you in the Excel workbook****
2. Convert the circumference into diameter (inches)_________
To get the diameter use the following formula d = Circumference/pi
3. Measure the height of the tree: ____________ (in inches from your triangle measurement)
a. Fold a square piece of paper in half so that it forms a triangle. The triangle will have one right (90 degree) angle and two 45 degree angles.
b. Hold the triangle near one eye so that the right angle is away from you, facing you, and one side is horizontal (parallel to the ground, assuming the ground is level).
c. Move back from the tree until you can sight the top of the tree at the top tip of the triangle. Close one eye to sight the tree’s top. You want to find the point where your line of sight follows the hypotenuse of the triangle to the very top of the tree.
d. Mark this spot and measure the distance from it to the base of the tree. This distance, plus your height(because you used the angle of elevation from eye level, not from the ground)is also the height of the tree. This works because the angle of elevation using your triangle is 45 degrees, and the tangent of 45 degrees = 1.
4. Estimate the green weight of your tree using the following table: Determine if your diameter is < 5” or > 5
****All calculations will be done for you in the Excel workbook****
Diameter |
This is an Algorithm (calculates weight in pounds) don't worry about that! |
d = diameter h = height To calculate an exponent use the ^ button on your calculator (example 102^exponent #) |
< 5 inches |
0.32214(d2h) 0.91330 |
|
> 5 inches |
0.19821 (d2)1.06419 (h) 0.91330 |
5. What is the green weight? (the number you just calculated above)
When trees are alive, their cells like yours, they have water in them. When a tree is cut down, the wood dries out. Green weight is the weight of the tree when it is alive.
Multiply the green weight by 0.6489 to get the tree’s dry wieght.
Write that weight here _________
6. Why do we need to convert to dry weight?
7. Find the carbon in your tree by multiplying the dry tree weight by 0.5. _________
8. How much CO2 did your tree sequester (store) in pounds?
Convert this to tons (divide by 2000)_______
Hint: The atomic weight of CO2 is 44.00995 grams per mole. We know from chemistry that the ratio of reactants and products for a chemical reaction is always the same. 44.00995 grams of CO2 are needed to put 12.01115 grams of carbon in a tree.
The ratio of CO2/carbon = 44.00995/12.01115= 3.66409.
If we multiply carbon * CO2/carbon, the carbons cancel and you are left with the weight of the CO2.
_________ (multiply your tree carbon by 3.66)
9. What was your carbon footprint? ___________
10. How does this one tree compare with the amount of carbon you put into the atmosphere?
11. What can you do to reduce the amount of carbon you put into the atmosphere?
12. From a population standpoint, what can we do to offset our carbon output even if we did not reduce our emissions?