Estimates of carbon fluxes from Poyang Lake wetlands vegetation in the growing season

Chen

Journal of Freshwater Ecology

2019

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 À2 h À1 , which were significantly higher than emissions in the meadow dominated by Artemisia selengensis (2.99 ± 1.67 mg CH 4 m À2 h À1 ). 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.

Section: Introductionmentioning

confidence: 99%

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

Chen

Journal of Freshwater Ecology

2019

“…Although it has been reported that the variation of microbial communities in soils is generally determined by climate and physicochemical properties (Baldwin et al, ; Wu et al, ), the factors that regulate the spatial patterns of microbial communities in lake sediments are still unclear. Poyang Lake, the largest freshwater lake in China, not only provides water resources for hundreds of millions of people, but also releases large amounts of greenhouse gases (GHG) to the atmosphere (Wan et al, ; Liu et al, ). Up to now, however, only Wu et al () reported upon bacterial community compositions within four samples from Poyang Lake.…”

Section: Introductionmentioning

confidence: 99%

Spatial patterns of benthic bacterial communities in a large lake

Internat. Rev. Hydrobiol.

Qiu

et al. 2015

To gain insights into the spatial pattern of microbial communities in Poyang Lake, we collected a total of 42 sediment samples from each of the four major parts of the lake in October 2010. We analyzed the spatial patterns of microbial biomass and microbial community composition using the phospholipid fatty acids (PLFA) method. The mean total microbial biomass was 2.28 mg PLFA/kg dry weight (wt) ranging from 0.25 to 6.56 mg PLFA/kg dry wt, indicating a high-spatial variation. The coefficients of variations (CVs) of the bacterial and fungal biomasses were 73 and 80%, respectively. In addition, the CVs of biomasses for the seven bacterial groups ranged from 62 to 92%, which included anaerobic bacteria, Gram-positive bacteria (Gþ), Gram-negative bacteria (GÀ), aerobic bacteria (AE), actinomycetes (A), sulfate-reducing bacteria (S), and methane-oxidizing bacteria. In our study, the ammonium concentrations both in the water and in the sediment were closely correlated to the total microbial biomass and the biomasses of bacterial groups, while the ratios of fungal to bacterial biomass (F/B) and GÀ/Gþ were correlated with ammonium concentration only in the water. In addition, F/B in the lake sediment was significantly correlated with the nitrogen content and the ratio of organic carbon to total nitrogen contents in the sediment (C/N). Moreover, the ammonium concentrations in the water and in the sediment, water dissolved organic carbon (DOC), sediment nitrogen content, and sediment organic carbon content were strongly linked to the spatial variation of bacterial community composition. Our results show that the C and N availability in the water and in the sediment are key predictors for microbial biomass and microbial community composition in Poyang Lake.

“…, and from 0.012 to 0.21 nmol m ¡2 s ¡1 for CO 2 , CH 4 , and N 2 O, respectively (Wan et al 2010;Chen et al 2013;Liu et al 2013). In recent years, Poyang Lake has suffered severely from water pollution, lake dredging, and water level fluctuations due to human activities and climate change (Lake et al 2000;Fang et al 2006).…”

Section: ¡1mentioning

confidence: 99%

Microbial biomass in sediments affects greenhouse gas effluxes in Poyang Lake in China

Journal of Freshwater Ecology

2015

Lake sediments accumulate large amounts of greenhouse gases (GHGs) through microbial decomposition of organic matter. To investigate the relationship between microbial biomass and GHG effluxes, we conducted a large-scale survey in Poyang Lake, the largest freshwater lake in China. We measured GHG effluxes using the floating chamber method at 42 sampling sites for three days and also measured microbial biomass using the phospholipid fatty acids (PLFAs) method. We found that the methane emission rate was positively and linearly related to total microbial biomass, anaerobic biomass, and anaerobic biomass excluding anaerobic methanotrophs. In addition, nitrous oxide efflux normalized to the amount of organic carbon in the sampling sediment (N 2 O/SOC) was significantly correlated with fungal biomass and the ratio of fungal biomass to total microbial biomass. But there were no significant relationships between the CO 2 and CH 4 normalized efflux in the sampling sediment and the biomasses of microbial groups. These results suggest that we could manage GHG emissions by considering the factors regulating microbial biomass in the lake sediments.