Oxygen production by urban trees in the United States

Oxygen production is often listed as a significant benefit of trees. To determine the importance of this ecosystem service, field data from 16 cities, collected during earlier studies from 1996 to 2004, was used to estimate the amount of oxygen produced by urban trees in the United States each year. Oxygen production is calculated as a function of carbon sequestration; thus tree biomass equations (adjusted for urban trees), estimated growth increments, and estimates of mortality and decomposition were included in the calculations. Total oxygen production for all trees in the United States was estimated at ca. 61 million metric tonnes, enough to offset consumption for approximately 2/3 of the U.S. population. The authors note that although this is a very big number, it is a relatively insignificant benefit considering the enormous amount of oxygen present in the atmosphere.