USDA US Forest Service Carbon sequestration website: This resource provides a variety of links to publications on carbon sequestration.
 
U.S. Department of Energy, Energy Information Administration (PDF): April 1998. This is a 16-page guide called Method for Calculating Carbon Sequestration by Trees in Urban and Suburban Settings which addresses quantifying carbon sequestration with trees.   

Trees for the Future (PDF):   2007 How to calculate the amount of CO2 sequestered in a tree per year. A 4-page description and formula is provided for calculating CO2 sequestration per tree.

US Forest Service Climate Change Tree Carbon Calculator:  On line program for download to calculate the amount of CO2 sequestered in a tree per year.

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