Methane emissions from the littoral zone of Poyang lake during drawdown periods

Abstract

Several studies have shown that lake littoral zones often support high methane (CH 4 ) emissions. In this study, we measured CH 4 emissions from two vegetation meadows in the littoral zone of Poyang Lake, China, from October 2014 to May 2015. CH 4 emissions in the meadow dominated by Carex cinerascens were 11.27 ± 11.29 mg CH 4 m −2 h −1 , which were significantly higher than emissions in the meadow dominated by Artemisia selengensis (2.99 ± 1.67 mg CH 4 m −2 h −1 ). Between-species differences in CH 4 emission were caused by differences in belowground biomass. The results also showed distinct seasonal variation in CH 4 emissions in this area; fluxes reached a maximum at the peak of the growing season and reached a minimum after the summer flood, when plants began to germinate. There were two peak values in the Carex meadow, and belowground biomass controlled the seasonality of CH 4 emissions. Our results suggest that plant biomass may be a key factor controlling CH 4 emissions in the littoral zone of Poyang Lake, highlighting that CH 4 fluxes vary with vegetation type in littoral wetlands and demonstrating that spatial variation in CH 4 emissions must be considered when estimating regional CH 4 emissions in Poyang Lake. Considering climate change and the operations of a proposed hydraulic engineering project, changes to the hydrologic regime in this region may significantly affect CH 4 emissions.