摘要：Understanding the origin and mechanisms controlling GHGs
(CO2, CH4 and N2O) emission spatially and temporally is critical for
evaluating future climate changes. Whether the controls on GHG dynamics
in urban ecosystem are similar to those in natural ecosystems are not fully
understood. In the current study, the aboveground (cover vegetation + soil)
and soil (including autotrophic and heterotrophic) CO2, N2O and CH4
fluxes and respective carbon stable isotopic composition (δ13C) of respired
CO2 at natural abundance level were simultaneously measured from a reestablished
grassland in the urban area of central Germany. The static
chamber system (combination of transparent and opaque modes) was
applied to assess the effects of intensive vegetation growth during two
weeks of April 2017. The values of CO2 fluxes obtained with both
transparent and opaque chambers differed significantly due to the
combined effects of the incoming photosynthetically active radiation
(PAR) and temperature on vegetation and belowground processes. The
average value of measured CO2 flux with opaque chambers was 9.14 ± 1.9
(mg m-2 min-1) vs. 2.37 ± 0.9 (mg m-2 min-1) with transparent chambers for
the re-established grassland. In contrast, soil CH4, as well as N2O fluxes
were not different significantly for both opaque-transparent chamber
measurements. Current magnitude provides the pattern of the urban
ecosystem source/ sinks potential during ambient light conditions.
其他摘要：Understanding the origin and mechanisms controlling GHGs (CO2, CH4 and N2O) emission spatially and temporally is critical for evaluating future climate changes. Whether the controls on GHG dynamics in urban ecosystem are similar to those in natural ecosystems are not fully understood. In the current study, the aboveground (cover vegetation + soil) and soil (including autotrophic and heterotrophic) CO2, N2O and CH4 fluxes and respective carbon stable isotopic composition (δ13C) of respired CO2 at natural abundance level were simultaneously measured from a re-established grassland in the urban area of central Germany. The static chamber system (combination of transparent and opaque modes) was applied to assess the effects of intensive vegetation growth during two weeks of April 2017. The values of CO2 fluxes obtained with both transparent and opaque chambers differed significantly due to the combined effects of the incoming photosynthetically active radiation (PAR) and temperature on vegetation and belowground processes. The average value of measured CO2 flux with opaque chambers was 9.14 ± 1.9 (mg m-2 min-1) vs. 2.37 ± 0.9 (mg m-2 min-1) with transparent chambers for the re-established grassland. In contrast, soil CH4, as well as N2O fluxes were not different significantly for both opaque-transparent chamber measurements. Current magnitude provides the pattern of the urban ecosystem source/ sinks potential during ambient light conditions.
