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 / Type of wood
Elm / Soft
Mountain Ash/Rowan / Hard
Willow / Soft
Oak / Hard
Plum, cherry, etc. / Hard
Poplar / Soft
Mulberry / Hard
Apple / Hard
Sycamore / Soft
Walnut / Hard
Ash / Hard
Beech / Hard
Chestnut / Hard
Birch / 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:

The radius is half the diameter and the circumference of the tree trunk is the same as the girth, so

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 / size / algorithm
Hard hardwoods / < 11inches / 0.38315 (D2H)0.92045
> 11 inches / 0.11710 (D2)1.16763 (H)0.92045
Soft hardwoods / < 11 inches / 0.26153(D2)1.12422(H)0.93871
> 11 inches / 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: