Lawns as a landcover change substantially alter evapotranspiration, CO₂, and energy exchanges and are of rising importance considering their spatial extent. We contrast eddy covariance (EC) flux measurements collected in the Denver, Colorado, USA metropolitan area in 2011 and 2012 over a lawn and a xeric tallgrass prairie. Close linkages between seasonal vegetation development, energy fluxes, and net ecosystem exchange (NEE) of CO₂ were found. Irrigation of the lawn modified energy and CO₂ fluxes and greatly contributed to differences observed between sites. Due to greater water inputs (precipitation + irrigation) at the lawn in this semi-arid climate, energy partitioning at the lawn was dominated by latent heat (LE) flux. As a result, evapotranspiration (ET) of the lawn was more than double that of tallgrass prairie (2011: 639(±17) mm vs. 302(±9) mm; 2012: 584(±15) mm vs. 265(±7) mm). NEE for the lawn was characterized by a longer growing season, higher daily net uptake of CO₂, and growing season NEE that was also more than twice that of the prairie (2011: −173(±23) g C m⁻² vs. -81(±10) g C m⁻²; 2012: −73(±22) g C m⁻² vs. -21(±8) g C m⁻²). During the drought year (2012), temperature and water stress greatly influenced the direction and magnitude of CO₂ flux at both sites. The results suggest that lawns in Denver can function as carbon sinks and conditionally contribute to the mitigation of carbon emissions - directly by CO₂ uptake and indirectly through effects of evaporative cooling on microclimate and energy use.

草坪作为土地覆盖物的变化会极大地改变蒸散量，CO ₂和能量交换，并且考虑到它们的空间范围，其重要性日益提高。我们对比了2011年和2012年在美国科罗拉多州丹佛市大都市地区在草坪和干燥草丛上采集的涡动协方差（EC）通量。发现季节性植被发育，能量通量和CO _2的净生态系统交换（NEE）之间存在紧密的联系。草坪的改良能量和CO ₂通量的灌溉，极大地促进了观测点之间的差异。由于在这种半干旱气候下草坪上的水输入（降水+灌溉）更多，所以草坪上的能量分配主要由潜热（LE）通量。结果，草坪的蒸散量（ET）是高草草原的蒸散量（ET：2011）：639（±17）mm vs. 302（±9）mm; 2012：584（±15）mm vs. 265（± 7）毫米）。草坪的NEE具有以下特点：生长季节更长，每天的CO ₂净吸收量更高，并且生长季节的NEE也是草原的两倍（2011年：-173（±23）g C m ^-2 vs. -81（±10）g C m ^-2； 2012：-73（±22）g C m ^-2与-21（±8）g C m ^-2）。在干旱年份（2012年），温度和水分胁迫极大地影响了CO ₂的方向和强度两个站点的通量。结果表明，丹佛的草坪可以充当碳汇，并有条件地减少碳排放-直接通过吸收CO ₂以及通过蒸发冷却对小气候和能源使用的间接影响。