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

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