Carbon storage and sequestration by urban trees in the USA

Field data from 10 U.S. cities was used to derive estimates for total national carbon storage and annual carbon sequestration by urban trees. Biomass equations, annual growth increment estimates, and estimates of mortality and decomposition were factors in calculating each city’s carbon storage and sequestration totals. These city totals were divided by the city’s tree cover to yield an average carbon density value per unit tree cover. The median of this value was multiplied by the estimated total urban tree cover for the conterminous United States. Values for total storage, total annual sequestration, storage and sequestration values per hectare are presented for the 10 cities; a subset of these values is presented for the continental U.S. and for eight regions. The estimated carbon storage for the urban forests of the United States is 704 million t C; the annual sequestration is estimated at 22.85 million t C/year.