Estimating the Tree's Age

• 1). Measure the chest-height circumference of the tree's trunk using the tape measure. Given that circumference equals two times pi, times the radius, find the radius of the tree. For example, if the circumference is 100 centimeters, divide it by two times pi to get a radius of about 15.9 centimeters.
  
  
• 2). Find the width of one annual growth ring. To do this, take any cross-section of the tree and divide its radius by the number of rings it contains. Growth rings are darker-colored rings that appear in concentric circles in the cross-section.
  
  Note that you are only looking for the width of one growth ring, not the number of growth rings. Therefore you may use a cross-section of a small branch and leave most of the tree intact.
  
  
• 3). Divide the radius of the tree's trunk by the width of one annual growth ring to get the tree's age. For example, a tree with a 24 inch trunk radius and a 2 inch annual growth ring is approximately 120 years old.
  
  

Calculating Carbon Sequestration

• 1). Open the pdf file in this article's resources section. It is a worksheet from the Department of Energy with tables that help to determine carbon sequestration rate.
  
  
• 2). Determine the species of your tree. Table 1 in the Department of Energy document will tell you whether that species has a slow, moderate or fast growth rate. A higher growth rate means a higher rate of carbon absorption.
  
  
• 3). Reference Table 2 in the document to find the tree's annual carbon sequestration rate. For example, a 15-year-old red pine is a fast-growing tree and puts away about 30 pounds of carbon per year.