QUANTIFYING THE ROLE OF MACROPHYTE LIFE FORMS FOR CARBON SEQUESTRATION IN CONSTRUCTED WETLANDS

Macrophyte communities perform an important function in the carbon cycle of inland waters by sequestering carbon in the sediment, but carbon sequestration as an ecosystem service of macrophyte communities is poorly understood, with very few measurements reported in the literature. We measured organic carbon sequestration in the sediments of three constructed wetlands, one supplied by stormwater, one by agricultural run-off, and one by treated wastewater. Using a piston corer we specifically developed for dense macrophyte stands, we took 183 sediment cores from the three sites, which were taken along 40 transects covering all types of macrophyte life forms and site morphologies. Drone imagery combined with ground measurements provided a map of macrophyte identity and annual productivity. We hypothesized that sediment carbon sequestration is positively related to the annual macrophyte productivity, and to the C:N ratio of the biomass. The data indicate that emergent macrophytes may contribute more to carbon sequestration than submerged or free-floating macrophytes, highlighting the roles of productivity and leaf litter recalcitrance in carbon sequestration efficiency. However, high spatial heterogeneity and superimposed morphological properties (e.g. water depth, flow paths) affirm the need to conduct highly resolved sampling. This study presents a working protocol for quantifying carbon sequestration in dense macrophyte stands and shows that macrophyte life forms and wetland morphology should be accounted for when quantifying carbon sequestration in constructed wetlands.

Presentation Preference: Standard Oral (12 Minutes)

Primary Presenter: Esra Reichert, Uppsala University (esra.reichert@ebc.uu.se)

Authors:

Esra Reichert, Uppsala University  (esra.reichert@ebc.uu.se)

Charlotte Grasset, Uppsala University  (charlotte.grasset@ebc.uu.se)

Pauline Balk, Uppsala University  (pauline.balk@ebc.uu.se)

Gillian Simpson, Uppsala University  (gillian.simpson@ebc.uu.se)

Sebastian Sobek, Uppsala University  (sebastian.sobek@ebc.uu.se)