Environmental and biological controls on carbon dioxide and methane exchange in a restored freshwater mineral-soil wetland at Frank Lake, Alberta

Abstract

Prairie pothole wetlands have been shown to be strong sinks for carbon dioxide (CO2); however, it is likely that these ecosystems are also strong emitters of methane (CH4), reducing their overall carbon (C) sequestration potential. This study presents growing season (May-September 2022) eddy covariance flux measurements of CO2 and CH4 at a prairie pothole wetland near High River, Alberta with extensive bulrush (Schoenoplectus acutus) vegetation. The study was conducted during a time-period that was warmer and had precipitation inputs that were altered from the long-term average pattern. Despite the warmer and relatively dry weather in 2022, the wetland was still an important sink for atmospheric CO2 during the study period with a net uptake of 49 g C m−2 resulting from 623 g C m−2 of photosynthesis and 575 g C m−2 of respiration. Methane flux expressed in CO2-equivalents (6 g C m-2 season-1) offset only ~12% of carbon sequestration based on CO2 only. This suggests that the valuable ecosystem service of C sequestration can still occur in a prairie pothole wetland even in warm and dry weather conditions.