Although urban areas only represent a small fraction of the earth's surface, they account for a large proportion of anthropogenic greenhouse gas emissions, including carbon dioxide (CO2). Further, high concentrations of CO2 sources (i.e. motor vehicles and industries) together with heavily managed and irrigated vegetation and soils create a unique carbon balance at the urban surface-atmosphere interface. Despite the importance of CO2 in urban areas, observations of carbon dioxide fluxes (Fc) between the urban surface and atmosphere are relatively rare and little is known on the role of urban vegetation and soils.

In this study, Fc is observed at the local scale in two suburban neighborhoods of Vancouver, BC, Canada. Both neighborhoods are composed of single family residences, but one neighborhood has substantially fewer trees and approximately twice the number of homes per area. Fc is observed using the eddy covariance method on two 28 m towers (approximately three times the mean building height). Surface conditions (surface wetness, soil temperature, volumetric water content, and soil respiration) are monitored at eight lots in the footprint area of the towers.

We discuss Fc observed at the two neighborhoods during a two-month period in summer 2008 and in comparison to a simultaneously operated flux tower at a rural reference site. Fluxes are discussed in terms of source area characteristics, traffic patterns, and effects of urban water use and irrigation.