Studies on carbon flux and carbon dioxide concentration in a forested region in suburban Baltimore
John Hom, Sue Grimmond, Dan Golub, Brian Offerle, Dave Nowak, Gordon Heisler, Rich Pouyat, and Wayne Zipperer
The purpose of this study is to characterize the carbon fluxes and carbon dioxide concentrations from a highly vegetated residential area of Baltimore traditionally classified as “non-forest”. This is the first permanent urban/suburban flux tower, and will improve our ability to verify carbon storage on an annual basis in traditionally “non-forest” areas and improve our estimates of carbon stocks for the U.S carbon budget. The preliminary results of our profile system has peak CO2 concentrations at the top of the 40 m profile exceeding 497 ppm, with a yearly mean CO2 concentration of 386 ppm. Our monthly estimates of net ecosystem exchange for a composite year, 2001-2002, show high CO2 uptake during the spring and early summer from the urban/suburban tree cover, having as much uptake as a natural temperate deciduous forest system. The residential area in the flux footprint of the Cub Hill site has patches of high vegetation cover, estimated to be 37% cover from satellite coverage. The effect of this “non forest” vegetation cover had a clear impact on the uptake of CO2 when leaves were on the trees, with uptake rates similar to that of a mature, deciduous forest ecosystem. The site is clearly a net carbon sink, highlighting the potential significance of suburban non-forest ecosystems to offset the emissions of CO2 known to occur in urban environments. Recently, the flux footprint has recently undergone significant disturbance, a 5 acre housing development has cleared the tree cover within 300 m of the tower, adding the treatment of carbon flux dynamics due to land use change to this flux site.
Keywords: urban, flux tower, CO2 concentration, non-forest carbon uptake

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