Characteristics of temporal variability of urban ecosystem-atmosphere CO₂, CH₄, and N₂O fluxes

¹ Unit of Engineering and Protection of Atmosphere, Faculty of Environmental Engineering, Wroclaw University of Science and Technology, Poland
² Dept. of Soil Science of Temperate Ecosystems, Georg August University of Goettingen, Goettingen, Germany

^* Corresponding author: jaroslaw.bezyk@pwr.edu.pl

Abstract

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.