How much carbon is stored in a tree in the park, and therefore, how much CO2 has it
removed from the atmosphere?
Step 1 : Identify a deciduous tree in the local park
Use a key to identify the species of tree, and determine the type of wood for the a tree. A list of common species can
be found in the table below.
Species
Elm
Mountain Ash/Rowan
Willow
Oak
Plum, cherry, etc.
Poplar
Mulberry
Apple
Sycamore
Walnut
Ash
Beech
Chestnut
Birch
Type of wood
Soft
Hard
Soft
Hard
Hard
Soft
Hard
Hard
Soft
Hard
Hard
Hard
Hard
Hard
Step 2: Measure the Girth of the tree
Use a tape measure to calculate the girth of the tree 1.5 meters from the base. Use this measurement to calculate
the Diameter of the tree:
Circumference = 2 π radius
The radius is half the diameter and the circumference of the tree trunk is the same as the girth, so
Diameter =
Tree girth
π
Step 3: Measure the height of the tree
There are several methods you can use to measure the height of a tree. For a variety of methods see additional
information sheet “methods of measuring tree height”.
Alternatively students can work out their own system for measuring tree height.
Step 4: Calculate the weight of the tree
Use the table below to determine the most appropriate equation for your tree
Tree species
Hard hardwoods
Soft hardwoods
size
< 11inches
> 11 inches
< 11 inches
> 11 inches
algorithm
0.38315 (D2H)0.92045
0.11710 (D2)1.16763 (H)0.92045
0.26153(D2)1.12422(H)0.93871
0.10743 (D2)1.12422(H)0.93871
D= Diameter of the tree, H= Height of the tree
Calculate the height of the tree
Step 5: Calculate the total green weight of the tree (including roots)
The calculations in the previous step give you the green/wet weight of the tree above ground. The root system
weighs about 20% of that of the tree above ground.
Therefore multiply your answer from step 4 by 1.2
The green weight of a tree is the weight when it is alive. When trees are alive their cells contain water in. Water can
make up almost 50% of the mass of some trees, although this varies with tree species.
Step 6: Calculate the dry weight of the tree
The average tree is 72.5% dry matter and 27.5% moisture (average obtained from research carried out by the
University of Nebraska).
Therefore multiply your answer by 0.725.
Step 6: Calculate the weight of carbon in the tree
The average carbon content is generally 50% of the tree’s total volume.
Therefore multiply the dry weight of the tree by 0.5
Step 7: Calculate the weight of carbon dioxide sequestered in the tree
The atomic weight of Carbon = 12.001115
Divide the total carbon weight in the tree by the atomic weight = Y
Carbon dioxide = CO2
Therefore in order to calculate the weight of carbon dioxide that the tree has sequestered you will need to add on
the weight of the associated oxygen molecules.
Atomic weight of Oxygen = 15.9994
O2 = 31.98
Total CO2 sequestered by the tree = 31.98 x Y + total weight of carbon
Step 8: Calculate the weight of CO2 sequestered in a tree per year
Divide the weight of CO2 by the age of the tree.
A rough estimate of the age of the tree:
Tree age =
Tree girth
2.5
“Tables for Estimating Total Tree and Product Weight and Volume of Major Southern Tree Species and Species Groups” by
Joseph Saucier and Alexander Clark III , Southwide Energy Committee, American Pulpwood Association Inc., Nov. 1985.
http://www.ncsec.org/cadre2/team18_2/students/science.html
“carbon storage an accumulation in united states forest ecosystems, general technical report WO 59” University of
Nebraska.