Q. My family owns a 40-acre woodlot of relatively mature deciduous trees. How many pounds of carbon dioxide does such a forest absorb in a typical year? And how many pounds of oxygen are emitted?

A. “An approximate value for a 50-year-old oak forest would be 30,000 pounds of carbon dioxide sequestered per acre,” said Timothy J. Fahey, professor of ecology in the department of natural resources at Cornell University. “The forest would be emitting about 22,000 pounds of oxygen.”