The green weight is the weight of the tree when it is alive. First you have to calculate the green weight of the above-ground weight as follows:
W(above-ground)= 0.25 x D^2 x H (for trees with D<11)
W(above-ground)= 0.15 x D^2 x H (for trees with D>11)
D = Diameter of the trunk in inches
H = Height of the tree in feet
The root system weight is about 20% of the above-ground weight. Therefore, to determine the total green weight of the tree, multiply the above-ground weight by 1.2:
W(total green weight)= 1.2 x W(above-ground)
The average tree is 72.5% dry matter and 27.5% moisture. Therefore, to determine the dry weight of the tree, multiply the total green weight of the tree by 72.5%.
W(dry weight)= 0.725 x W(total green weight)
The average carbon content is generally 50% of the tree’s dry weight total volume. Therefore, in determining the weight of carbon in the tree, multiply the dry weight of the tree by 50%.
W(carbon) = 0.5 x W(dry weight)
CO2 has one molecule of Carbon and 2 molecules of Oxygen. The atomic weight of Carbon is 12 (u) and the atomic weight of Oxygen is 16 (u). The weight of CO2 in trees is determined by the ratio of CO2 to C is 44/12 = 3.67. Therefore, to determine the weight of carbon dioxide sequestered in the tree, multiply the weight of carbon in the tree by 3.671.
W(carbon-dioxide) = 3.67 x W(carbon)
W(above-ground)= 0.25 D2 H= 0.25(82)(15) = 240 lbs
W(total green weight)= 1.2 x W(above-ground)= 1.2 x 240=288 lbs
W(dry weight)=0.725 x W(total green weight)=0.725 x 288=208.8 lbs
W(carbon)= 0.5 x W(dry weight)= 0.5 x 208.8 = 104.4 lbs
W(carbon-dioxide)= 3.67 x W(carbon) = 3.67 x 104.4 = 382.8 lbs CO2 sequestered in 10 years.
Here's their sources!
Carbon sequestration: how much can forestry sequester CO2?, Egbuche, Christian. Forestry Research and Engineering: International Journal. 2018.
“Total-Tree Weight, Stem Weight, and Volume Tables for Hardwood Species in the Southeast,” Alexander Clark III, Joseph R. Saucier, and W. Henry McNab, Research Division, Georgia Forestry Commission, January 1986.
“Heating With Wood: Producing, Harvesting and Processing Firewood,” Scott DeWald, Scott Josiah, and Becky Erdkamp, University of Nebraska – Lincoln Extension, Institute of Agriculture and Natural Resources, March 2005.