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V. Oxygen Production <br />Oxygen production is one of the most commonly cited benefits of urban trees. The annual oxygen production of a <br />tree is directly related to the amount of carbon sequestered by the tree, which is tied to the accumulation of tree <br />biomass. <br />Trees in City of Pleasanton are estimated to produce 888.4 tons of oxygen per year.' However, this tree benefit is <br />relatively insignificant because of the large and relatively stable amount of oxygen in the atmosphere and extensive <br />production by aquatic systems. Our atmosphere has an enormous reserve of oxygen. If all fossil fuel reserves, all <br />trees, and all organic matter in soils were burned, atmospheric oxygen would only drop a few percent (Broecker <br />1970). <br />Table 2. The top 20 oxygen production species. <br />Species <br />Oxygen <br />(ton) <br />Gross Carbon <br />Sequestration <br />(ton/yr) <br />Number of Trees <br />Leaf Area <br />(a cre) <br />Coast redwood <br />99.37 <br />37.26 <br />2,006 <br />150.81 <br />Sycamore spp <br />85.96 <br />32.23 <br />2,734 <br />213.45 <br />Coastal live oak <br />78.96 <br />29.61 <br />2,191 <br />108.69 <br />California valley oak <br />64.36 <br />24.13 <br />1,454 <br />78.73 <br />Chinese pistache <br />54.96 <br />20.61 <br />1,605 <br />22.83 <br />Ash spp <br />45.90 <br />17.21 <br />1,045 <br />88.35 <br />Sweetgum <br />34.67 <br />13.00 <br />977 <br />58.30 <br />Callery pear <br />33.51 <br />12.57 <br />764 <br />29.02 <br />White mulberry <br />25.92 <br />9.72 <br />261 <br />23.18 <br />Mugga ironbark <br />23.57 <br />8.84 <br />87 <br />18.46 <br />Common crapemyrtle <br />19.93 <br />7.47 <br />1,378 <br />6.50 <br />Tulip tree <br />19.00 <br />7.12 <br />302 <br />32.12 <br />Deodar cedar <br />17.81 <br />6.68 <br />339 <br />16.91 <br />Camphor tree <br />16.22 <br />6.08 <br />215 <br />9.22 <br />Hind walnut <br />15.92 <br />5.97 <br />275 <br />22.29 <br />Willow -leaved gimlet <br />11.33 <br />4.25 <br />95 <br />14.79 <br />Holly oak <br />9.21 <br />3.45 <br />150 <br />10.21 <br />Turkish pine <br />8.42 <br />3.16 <br />158 <br />12.44 <br />Silver maple <br />7.95 <br />2.98 <br />123 <br />12.97 <br />Chinese elm <br />7.79 <br />2.92 <br />117 <br />4.47 <br />Page 13 <br />75 of 219 <br />