Continuous measurements of net CO2 exchange by vegetation and soils in a suburban landscape

[1] In a suburban neighborhood of Minneapolis–Saint Paul, Minnesota, USA, we simultaneously measured net CO2 exchange of trees using sap flow and leaf gas exchange measurements, net CO2 exchange of a turfgrass lawn using eddy covariance from a portable tower, and total surface-atmosphere CO2 fluxes (FC) using an eddy covariance system on a tall tower. Two years of continuous measurements showed that net CO2 exchange varied among vegetation types, with the largest growing-season (Apr–Nov) net CO2 uptake on a per cover area basis from evergreen needleleaf trees ( 603 g C m ), followed by deciduous broadleaf trees ( 216 g C m ), irrigated turfgrass ( 211 g C m ), and non-irrigated turfgrass ( 115 g C m ). Vegetation types showed seasonal patterns of CO2 exchange similar to those observed in natural ecosystems. Scaled-up net CO2 exchange from vegetation and soils (FC(VegSoil)) agreed closely with landscape FC measurements from the tall tower at times when fossil fuel emissions were at a minimum. Although FC(VegSoil) did not offset fossil fuel emissions on an annual basis, the temporal pattern of FC(VegSoil) did significantly alter the seasonality of FC. Total growing season FC(VegSoil) in recreational land-use areas averaged 165 g C m 2 and was dominated by turfgrass CO2 exchange (representing 77% of the total), whereas FC(VegSoil) in residential areas averaged 124 g Cm 2 and was dominated by trees (representing 78% of the total). Our results suggest urban vegetation types can capture much of the variability required to predict seasonal patterns and differences in FC(VegSoil) that could result from changes in land use or vegetation composition in temperate cities.